I Judge People By Their Grammar and Knowledge of Phenol

March 10th, 2007

Some commenters in a previous thread took umbrage at the fact that I admit to judging people by their grammar. Well, I do, and I’m not going to change anytime soon. I’ll put poor grammar on par with poor hygiene, dressing like a slob, and bad table manners—while they don’t automatically invalidate a person’s ideas, they will cause me to treat anything the person says with more skepticism than usual. With respect to the four errors I found in the first paragraph of this recent paper from Org. Lett., the misplaced apostrophe in “Evan’s” was the most aggravating. While the chemistry in the paper was good, as The Chem Blog has noted, the authors’ lack of attention to detail was borderline disrespectful. I expected more from one of the most storied labs in synthetic organic chemistry.

A lot of people will complain, “So what if I make a few mistakes? Why don’t you focus on the ideas?” That’s the thing: I want to focus on your ideas, so why don’t you stop whining and learn to write properly? The rules of grammar are not up for discussion—just follow them out of courtesy to your readers. Grammatical errors are distracting and will cause them to lose sight of what you’re writing. If you are someone who has no trouble reading documents riddled with mistakes, that’s great, but when you are writing, you aren’t writing for yourself.

While grammar shouldn’t be the sole criterion for evaluating intelligence, I will admit to judging some things by a relatively obscure set of criteria. For instance, I have a list of favorite subjects for judging textbooks and course packets. One of the first things I do to determine the quality of a sophomore organic textbook is to look in the index for phenol. As you all know, phenol is more acidic than “standard” aliphatic alcohols. If you took a survey, most people would ascribe this fact to a resonance effect by drawing the following structures:

There are a number of variations on this theme, including drawing out all of the unhybridized p orbitals and showing that an orbital on oxygen containing a lone pair can overlap with the pi system, thereby allowing for increased delocalization of the extra negative charge density.

It turns out that an inductive effect—not a resonance effect—is the predominant reason for the increased acidity of phenol relative to aliphatic alcohols. Whereas aliphatic alcohols have a C(sp3)—O bond, the carbon to which the hydroxyl group is bonded in phenol is sp2 hybridized. The increased s-character of the carbon orbital used to form the C—O bond makes it more electron withdrawing, which leads to greater stabilization of the conjugate base of the alcohol. For the purpose of comparison, look at the pKa of phenol compared to that of enol tautomer of acetone:

Even though you can only draw two resonance forms showing delocalization of the extra negative charge in the conjugate base of the enol (vs. four for phenol), the acidities of the two protons differ by less than an order of magnitude. For those interested, these data come from Evans’ Chem 206 lecture notes (Lecture 20, restricted access), where the point is hammered home in glorious detail. Professor Evans’ PowerPoint slides should be framed and displayed in the Smithsonian.

While we’re discussing phenol and errors, let me also use this example to illustrate one of the main problems with Wikipedia. Wikipedia is great, but it is home to a number of edit-happy users who think they know more than they actually do. If you look at the discussion page for phenol, someone actually addressed the resonance vs. inductive effect argument, but was unceremoniously (mis)corrected by another user, who references an incorrect explanation on the Internet. Thus, the main article (as of today) gives the incorrect (resonance > inductive) explanation:

Phenol has a limited solubility in water (8.3 g/100 ml). It is slightly acidic: the phenol molecule has weak tendencies to lose the H+ ion from the hydroxyl group, resulting in the highly water-soluble phenoxide anion C6H5O. Compared to aliphatic alcohols, phenol shows much higher acidity; it even reacts with NaOH to lose H+ whereas aliphatic alcohols do not. This is due to orbital overlap between the oxygen’s lone pairs and the aromatic system, which delocalizes the negative charge throughout the ring and stabilizes the anion. This effect is attenuated, however, due to oxygen’s relatively high electronegativity. [1]

God knows that we in the chemical blogosphere love the Wikipedia, but read it with skepticism.

This concludes today’s lesson. Your homework for the weekend is to find all of the grammatical errors in this post. For extra credit, find an error in a chemistry article on Wikipedia, fix it, and brag about having done so in the comments. Class dismissed.

Previous Comments

  1. My lord, My Guide Says:
    March 10th, 2007 at 6:55 am Since you make opinion of people based on their usage of grammer, I think i should better stop commenting (and learn English, instead, using that time) to restore my dignity. It is too late for me my dear…
  2. yepyep Says:
    March 10th, 2007 at 7:32 am Have you considered that many people speak 3-4 languages and the fact that they can write/speak English (in addition to 2-3 other languages) almost correctly is a pretty great achievement already?How is your, say, Spanish or French? Any spelling mistakes?
  3. Felix Says:
    March 10th, 2007 at 8:16 am I judge people by the units they use. Mr. Evans used kcal, so he lost I am asking myself if you can accurately and precisely determine the pKa of acetone-enol. Besides that it does not convince me that acetone lies on a regression line made from two data points (actually the fact that phenol is to the left of that line shows a conjugation effect).Anyway it’s an interesting thing that I should remember.
  4. European Chemist Says:
    March 10th, 2007 at 8:19 am My thoughts precisely. Expecting that anyone in the world would be capable to write an article in perfect English is utopic. Criticising the foreign post-doc who wrote the paper for not being 100% grammatically correct is a bit arrogant. Blaming the (probably very busy) supervisor for not correcting each article word-by-word is not fair.
    But overlooking the work of the Editorial Office in letting this paper come out without taking an appropriate look at grammar is somewhat surprising, especially coming from you… as I see it, the ACS Publications division receives more than enough money to pay people to do this. Stop nagging the authors or feeling “disappointed” because the lab it comes from “should have done better”.
  5. Felix Says:
    March 10th, 2007 at 8:22 am and I judge people by how they use “maths”: R = OR is nothing but a contradictory statement. Just like it is with grammar: everyone knows what is meant but it doesn’t look nice and it doesn’t seem like the person spent a lot of time and thought writing the text.
  6. Paul Says:
    March 10th, 2007 at 8:43 am Excellent. The bleeding hearts are out in force, armed with low expectations and plenty of excuses.There is certainly enough blame to go around; I have no problems including the copy editors at ACS Pubs.And I’m not saying that a resonance effect is completely absent, just that the inductive effect clearly predominates.
  7. Karl Says:
    March 10th, 2007 at 9:51 am How can you say the inductive effect clearly predominates based on that one example of the acetone enol? In that case, it seems possible that the one resonance structure of the enol could be better than all of the resonance forms of phenoxide. That is, each of the resonance structures of phenoxide breaks the aromaticity of the ring, unlike with the enol, which might make them poorer contributors to the overall hybrid than the lone resonance contributor of the acetone enolate. (Common misconception: 2 resonance structures is not always better than 1; it depends on their overall contribution to the hybrid). I’m not saying you’re wrong about the inductive effects, but I think it’s difficult to say this definitively with only the two pKas in hand.
  8. Mark C R UK Says:
    March 10th, 2007 at 10:28 am Wiki should be used as nothing more as a “portal” for quick ref then further lookup of something.We had this debate at Milo’s musings… a while ago.Paul – why not go impart some of your glorious knowledge onto the wiki?
  9. Mitch Says:
    March 10th, 2007 at 11:15 am I never trust a wiki I didn’t write myself.Mitch
  10. Uncle Al Says:
    March 10th, 2007 at 12:01 pm A (putative) American who cannot speak and write grammatical English is a dunce. American zero-goal education celebrates the empowerment of stupidity – every child left behind. Elitism insists the better is preferable to the worse. Uncle Al is an elitist.Anybody who publishes in English should/must run it by an English editor. English is not pidgin.Why stop with sp2? Compare C-H acidities in methane, ethylene, benzene, and acetylene. #C-OH is respectably acidic on paper (# being a triple bond). If somebody likes ethene and ethyne better, “polythene” isn’t New World patois.
  11. excimer Says:
    March 10th, 2007 at 12:02 pm I agree with Karl. While Evan’s (tee hee) makes the valid point that phenol’s acidity is not primarily due to resonance, I don’t think it’s valid to say it’s there is no resonance effect. Evans unforatunately leaves out the case of o,p- vs. m-nitrophenol, which demonstrates a possible resonance effect. The pKa of o,p-nitrophenol is around 7 while m-nitrophenol is around 8- an order of magnitude difference. Of course, the inductive effect appears to have a higher impact on the overall acidity of nitrophenols as the pKa of phenol is two orders of magnitude higher than m-nitrophenol, there appears to be a resonance effect as well. Evans’ point is correct, but you’re taking it too far. Anslyn and Dougherty says that “it is often difficult to separate resonance from inductive effects,” and that’s where I stand as well. As Karl hints at, resonance also tends to be a more complicated issue than the brushjob given to sophomores.
  12. Bronwen Says:
    March 10th, 2007 at 1:04 pm This is not entirely related, but felt a strong need to communicate this with someone.A few weeks ago I created an entry in Wikipedia [Protocol (natural sciences)], and when I looked at it today, it was completely different both in content and philosophy to what I had originally written! It has developed a life independant of me.This is the first time that I have experienced this so am a bit stunned. Was definitely (initially) distrustful of the new content, because of the new author’s grammar, but maybe it just needs to be copyedited a bit…
  13. Mark C R UK Says:
    March 10th, 2007 at 1:36 pm This sounds like any academic debate Bronwen!
  14. Ψ*Ψ Says:
    March 10th, 2007 at 1:40 pm Paul: Just how picky are you about grammar?
    (I blame the copy editors, by the way)
  15. Stu Says:
    March 10th, 2007 at 2:10 pm I agree with Karl and Excimer – it’s certainly not wrong to draw those resonance structures. It’s another carbon removed, but to compare the inductive effects of sp2 vs sp3, consider acrylic acid (pka 4.25) and propanoic acid (pka 4.86), so, at that distance, the inductive effect buys you 0.6 pka units, when it’s right next to the charged atom it’s going to be a bigger effect, but I bet it doesn’t account for the full difference of 6…
  16. Mitch Says:
    March 10th, 2007 at 2:12 pm Karl: Are you sure you are breaking aromaticity since the electrons are technically still in the conjugated p-orbital system. Although, now there is that destabilizing extra electron.Mitch
  17. Paul Says:
    March 10th, 2007 at 2:13 pm I expect flawless prose in formal documents like scientific papers. I generally care much less about blog posts/comments, e-mails, and spoken conversation. A lot of times you have to use weird grammar and punctuation for something to read the same way you would say it. Basically, anything that you proofread more than three times should be error-free. And, of course, some violations are more egregious than others. So relax, I don’t read JACS or C&EN with a red pen. It’s just that when someone strings together a number of errors (like four in one paragraph), it is difficult not to notice.
  18. Karl Says:
    March 10th, 2007 at 3:14 pm Mitch: Formally the resonance structures of phenolate are not aromatic by Huckel’s rules since they (formally) have 7 electrons in the ring (4 from the two double bonds, 2 from the lone pair, plus one electron from the double bond to oxygen).
  19. Mitch Says:
    March 10th, 2007 at 3:54 pm Karl: I understand. I personally wouldn’t say adding a single electron “breaks” aromaticity though, but I know what angle your coming from.Mitch
  20. Chemgeek Says:
    March 10th, 2007 at 7:37 pm Face it, Organic chemistry is hard for most students to learn. There are several reasons for this. One solution is to over-simplify things. These are occasionally gross oversimplifications that cause us teachers to cringe when we teach them. But, we have to start somewhere. There is so much to learn at the sophomore level that we just can’t get into all of the details. The phenol resonance/inductive effect is just one of many examples of things we “lie” about at the sophomore level. Usually by the time these students reach the advanced organic courses, we can talk more about the realities. Then it gets a lot more fun. Sadly, most students never make it that far. The bottom line is that Organic chemistry is so broad and complex, we are forced to make unfortunate sacrifices.
  21. Wolfie Says:
    March 10th, 2007 at 10:48 pm Just for coincidence, I saw the Meistersingers of Nuremberg today at the Met for the first time in my life. We all are quite good, or at least, we hope so. But, the character of Beckmesser there was really somewhat inconvenient. So, what is now the matter for an elite student from the world’s richest university, with an absolutely German sounding proficience (Bracher), to explain what it is all about ??
  22. Wolfie Says:
    March 10th, 2007 at 10:55 pm provenience, I wished to say, you almost see what the problem is
  23. Wolfie Says:
    March 10th, 2007 at 11:13 pm And, while we don’t think we are animals, we still like the movie” March of the Penguins”. They have no Harvard grade nor grammatical problems, but they find and caress their offspring, it seems, all over the world.
  24. Axicon Says:
    March 11th, 2007 at 12:00 am This may be a related question:How many of you offer grammar suggestions in articles you are peer reviewing?
    (disclaimer: this is a symbolic question since we all know that only PI’s see and review papers)Many of my colleagues go line-and-item on many of the papers. Personally, I only worry about
    the content of the paper because I think the grammar is the editor’s job. If it is a mess I simply
    say so and do not go into detail.
  25. Will Sharpless Says:
    March 11th, 2007 at 1:22 am the forms must be obeysed… else…something different might happen!!!!
    and i know I speak for all when i say we must crush it!!!
  26. anon Says:
    March 11th, 2007 at 1:49 am mistake 1: umbrage is perhaps the wrong word–and one wouldn’t take umbrage AT a fact, i suppose they would take umbrage UNDER a fact…
  27. Paul Says:
    March 11th, 2007 at 3:09 am Anon: There is nothing wrong using the word “umbrage” in this context. Also, “at” is the correct preposition, in that you do “take umbrage at” something.For more info, refer to the Random House and Merriam-Webster unabridged dictionaries. Thanks for playing.
  28. anon Says:
    March 11th, 2007 at 3:18 am I stand corrected. I should also learn not to try and outpedant the master.
  29. Imperator Says:
    March 11th, 2007 at 12:17 pm Judging by someone’s grammar is not a good idea…especially when it comes to speech itself. Sure, in a professional setting such as a journal article, one should expect a degree of coherence in writing, but the so-called rules of grammar are NOT absolute and not rigid. Grammar itself is a human construction – period. It is not an inherent property of languages…its a property tacked on by humans. Languages come and go, changing all of the time, but grammar is supposed to never change. Some of those grammar books that are the “authority” on what one should say, do, and write are themselves pretty antiquated. People just don’t realize that languages are not uniform. Just because someone does not speak grammatically correct does not mean that you are a better person than they are. There are much better ways to judge a person than by that.As for scientific literature, I would expect the manuscript to go through a rigorous editorial process, and it is likely that did not occur if there are errors in the paper. Considering there are people reading the papers (or at least possibly reading for most) who come from a wide variety of language backgrounds, it is a must.The phenolate anion certainly had aromatic character to it. It may not be a pure case of an aromatic compound according to the “rules” but then again, there are other compounds that should not be aromatic and in fact sorta act like they are. And of course, there are degrees to aromaticity.And I agree, it can’t be a case of pure induction. The resonance has to have some sort of effect even if it is not the major one.
  30. Orthogon Says:
    March 11th, 2007 at 4:11 pm The closest thing to a mistake I see is the comma in this compound predicate. Although I wouldn’t have used the comma, one could certainly make an argument for it.“If you look at the discussion page for phenol, someone actually addressed the resonance vs. inductive effect argument, but was unceremoniously (mis)corrected by another user, who references an incorrect explanation on the Internet.”From the Chicago Manual of Style:6.34 Compound predicate

    A comma is not normally used between the parts of a compound predicate—that is, two or more verbs having the same subject, as distinct from two independent clauses—though it may occasionally be needed to avoid misreading or to indicate a pause.

  31. milo Says:
    March 12th, 2007 at 10:05 am Does this explaination account for the acidity of p-nitrophenol (pKa 7.1)? I would guess that is it was predominatly an inductive effect, as asserted, then the NO2, which is 4 sigma bonds away would have a minor effect on the acidity of the -OH. Am I missing something obvious here?
  32. Hap Says:
    March 12th, 2007 at 11:22 am Imperator,I don’t think grammar is inherent to thought or language, but it is a useful system of conventions. When one writes, one writes to be understood by others, and it makes sense to play by the same set of rules (which is what grammar provides). There are enough misunderstandings based on factual misunderstandings, differences in context, implication, and other issues to add another method of misunderstanding to the mix, particularly when the ability to minimize grammatical mistakes is readily available. Second, if one can’t be bothered to run grammar and spellcheck on something published for one’s professional peers, readers might wonder how much effort the author put into anything else in the paper. Finally, journal articles are written not just for now but for the future as a part of a repository of chemical knowledge; following the rules of grammar helps people in the future to understand what you have said now. Informal, unwritten conventions are not derivable from those rules and, unless they are adopted by people in general, are likely to be misunderstood by future readers of your paper.I wonder if the sloppiness in grammar doesn’t correlate in part with some authors’ willingness to see papers as a means to their own aggrandizement rather than as a way to communicate useful results to others.
  33. Phlogiston Says:
    March 12th, 2007 at 11:29 am I think a lot of people are missing the point about what Evans is saying about phenol, i.e. it is primarily an inductive effect. Organic chemists tend to place too much emphasis on the orbital portion of the wave equation and forget about the electrostatic portion. This doesn’t mean that there is no resonance effect, it’s just smaller than the inductive effect. Putting nitro substituents increases both inductive withdrawing (even in the para position), but the nitro group itself gives resonance stablization to the negative charge as well. In other words, the coefficients on the electrostatic component of the generalized wave equation increase, but the orbital contribution increases even more for para-nitrophenol. You can model all of this easily in Spartan. Map out the orbitals and also check out the electrostatic charges.
  34. pi* Says:
    March 12th, 2007 at 11:32 am so how many bonds does a sulfone have?
  35. SSBiochem Says:
    March 12th, 2007 at 11:46 am Poor grammer in published work is painful, but not really more so than the poor writing that it generally accompanies. Glance through this famous Orwell essay and then fantasize about how much easier all of our lives would be if scientific papers followed his rules.http://mla.stanford.edu/Politi…..nguage.pdfOh, the native language of the authors is no excuse. I have yet to find a University without an English department full of starving grad students. They’d probably edit a paper for a pizza, but submitting a paper that truly does allow a reader to focus on the ideas should be worth a lot more.
  36. J Says:
    March 12th, 2007 at 1:30 pm How do they calculate the pKa of a proton on an enol?
  37. PG Says:
    March 12th, 2007 at 1:30 pm 99.9% of all organic chemistry papers break Orwell’s rule #4: Never use the passive when you can use the active.PS: the supplementary info of that Org. Lett. paper by Trost is full of mistakes too. A bit embarrassing coming from a member of the paper’s advisory board…
  38. AC Says:
    March 12th, 2007 at 3:00 pm So, Paul, which sophomore textbooks are up to snuff when it comes to phenol acidity? Aside from Evans’ 30/206 notes and a brief aside in Anslyn and Dougherty, I can’t say that I’ve seen a textbook go into this.
  39. Paul Says:
    March 12th, 2007 at 4:09 pm Anslyn and Dougherty is a wonderful text, isn’t it?As for sophomore texts, I have yet to see a nice treatment of the acidity of phenol. I think that part of the reason is what Chemgeekbrings up in #20: when teaching intro, we don’t want to lose sight of the forest for the trees. That said, the subject should be glossed over instead of explained incorrectly (using resonance as the primary reason).Wade (3rd ed.) and Loudon (see Evans’ note) completely s— the bed when it comes to phenol acidity. Jones (1st) ignores the issue in the text, but it is a practice problem, and the solutions manual bollocksed it up. For my money, Jones is geneally ahead of the curve on most of these issues. He does things like explain the importance of stereoelectronic and solvation effects in explaining trends in the acidities of alcohols, when most other authors attribute the trend to an inductive effect, saying “alkyl groups are electron donating.” If I were to teach sophomore organic, I’d make my own coursepack, but would have Jones as the textbook. His explanations and practice problems are, in general, quite good.
  40. Paul Says:
    March 12th, 2007 at 4:26 pm Hap: I agree totally.Phlogiston: Thanks for writing that out. The point, everyone, is not that there is no resonace effect, just that the observations are probably best primarily attributed to an inductive effect.Pi*: Yeah, those S=O bonds aren’t “double bonds” in the same way that C=C double bonds are.SSBiochem: Thanks for the link. I saved a copy of the pdf.

    J: I actually looked around for that (not thoroughly) but couldn’t find anything. I have a guess, but will look further before polluting google with incorrect info.

  41. Wolfie Says:
    March 12th, 2007 at 9:16 pm Anyone who wishes to meet me at a Wolfiade ? (You don’t know what this is ?? gee…)there is one in New York next week, seehttp://www.acfny.org/downloade…..downl=true
  42. Paul Says:
    March 12th, 2007 at 9:32 pm Wolfie, you just made the 1000th comment in the history of this blog. I had a bad feeling it would be you.
  43. eugene Says:
    March 12th, 2007 at 9:37 pm Dammit. That means I was 999! Oh well, it’s only appropriate that you’re 1001.
  44. eugene Says:
    March 12th, 2007 at 9:38 pm No wait, it’s the other way around. Still, I feel like I’m part of history.
  45. Wolfie Says:
    March 12th, 2007 at 10:41 pm records are for the record, just take it as such
  46. ZAL Says:
    March 13th, 2007 at 3:53 am who posted comment 666 then?
  47. none Says:
    March 13th, 2007 at 7:55 am what about comment # 69?
  48. Satan Says:
    March 13th, 2007 at 8:32 am Every time I post, it’s comment 666.
  49. Wavefunction Says:
    March 13th, 2007 at 2:19 pm Speaking of grammar, Prof. Evans in his handout says “Lets calculate…” instead of “Let’s calculate…”The apostrophe remains elusive for many.
  50. weirdo Says:
    March 13th, 2007 at 9:01 pm So, Uncle Al and Paul;
    Since accuracy is of primary concern to you both, do you think a citizen of Mexico, or Canada, or Peru should be offended by your using the word “American” to refer exclusively to denizens of the U.S.A.?
    Just wondering. Bad grammar is not the only thing that drives me nuts!
  51. Paul Says:
    March 13th, 2007 at 9:17 pm Look up “American” in the dictionary. Using it to refer to things associated with the United States is perfectly acceptable. Also, why are you picking on me? I didn’t even use the word in this post.Why do you hate me?
  52. excimer Says:
    March 13th, 2007 at 10:52 pm I think Penny Arcade could teach us a thing or two about punctuation.
  53. PMP Says:
    March 14th, 2007 at 9:58 am Speaking of pKa values, I find it strange that many organic chemists are obsessed with pKa’s measured in water or DMSO while most of their reactions (where these things matter) are actually performed in, say, THF or dichloromethane.In any case, the Evans explanation is too simplistic. In fact, the standard textbook explanation is most likely to be correct, for the following reasons:
    1) If electronegativity (in this case, sp2 vs. sp3 hybridization) were the key to acidity, one would expect acidities to drop in the series HF – HCl – HBr – HI. Exactly the opposite is observed, with HI being strongest although I is the least electronegative element.
    2. Benzoic acid is only slightly more acidic than acetic acid (0.5 pKa units). Stu (#15) mentions acrylic acid vs. propanoic acid, where the difference is of equal magnitude.
    3. If the electronegativity explanation were valid, the reason for the higher acidity of carboxylic acids vs. enols and phenols should lie in the higher electronegativity of oxygen in the carboxylic acids (O=C-O-H) vs. enols (C=C-O-H). However, in the gas phase, the acidities of phenols approach those of carboxylic acids. p-Nitrophenol is in fact slightly more acidic than p-nitrobenzoic acid in the gas phase!
    See: http://dx.doi.org/10.1021/jp046990i
  54. Hap Says:
    March 14th, 2007 at 3:01 pm 53.1) Isn’t solvation the big difference here, or are the acidities in the gas phase? In solution, the solvation energies overwhelm the effect of electronegativity (with fluorine, the electronegativity also increases the hydrogen bonding which alters the solvation).53.2) Inductive effects decrease with distance – the sp2 carbons aren’t at the sites of acidity but another carbon away, which should decrease their effects on acidity accordingly.53.3) Doesn’t the similar acidity of p-nitrophenol and p-nitrobenzoic acid argue more, not less, strongly for an inductive (or solvation) explanation? Carboxylic acids are nearly the ideal situation for selective resonance-based stabilization of the anions over the free acids while enols and phenols are less optimal (since the resonance forms of the anions aren’t equivalent). While there are a greater number of resonance forms to stabilize a negative charge in phenolates than in carboxylates, the resonance forms aren’t as good and should offer less resonance stabilization to the phenolate (in addition to breaking aromaticity). If phenols and carboxylic acids are of similar acidity in the gas phase, that should imply that the difference in resonance energies has little effect on the differences in acidity.
  55. PMP Says:
    March 14th, 2007 at 6:13 pm Part II.3) Why should the delocalization of the negative charge be less effective in phenols than in carboxylic acids? Computationally it has been found that there is significant delocalization in the phenolate ion, including shortening of the C-O bond relative to PhOH, implying significant pi delocalization in the phenolate anion:http://dx.doi.org/10.1021/ja993730jThis shortening is also evident in X-ray structures (typically for phenols, CCDC PHENOL03, the C-O is ca 1.37 Å, for phenolates, CCDC ROQFEI01 is a PhONa, the C-O is ca 1.28 Å, this value of course varies between different phenolate salts and solvated complexes).

    Of course the pi delocalization is quite effective in carboxylate anions, and this naturally explains carboxylic acids are – indeed – acids. However, to argue that phenolate anions are somehow less delocalized simply because its “resonance structures” look more awkward does not constitute a very convincing argument.

    A recent study by Holt and Karty


    addresses the gas phase acidities of formic acid, vinyl alcohol, and methanol. They conclude that roughly two thirds of the enhanced acidity of vinyl alcohol relative to methanol is due to resonance effects (ie pi delocalization) and the rest is explained by inductive effects. If these trends would hold true with phenol vs MeOH or CyOH, the inductive effects would contribute ca 2 pKa units to the difference and the delocalization should then explain the remaining 4 pKa units.

  56. PMP Says:
    March 14th, 2007 at 6:17 pm This is really strange – Paul, could you delete my comments 55 and 561) Solvation plays a role in allacid-base reactions. The trend with hydrogen halides (HF weakest, HCl, HBr, HI (strongest)), however, persists also in the gas phase:http://dx.doi.org/10.1021/jp01164072) Yes, accordingly – but not by a factor of 10^6! The figure for khi (electronegativity) that Evans gives for sp2 carbon on his own lectures is 2.8. If electronegativity alone would play a role in determining the acidity of acids of the type H-O-X, the acidities would increase in the order

    H-O-CH3 – H-O-CH=CH2, H-O-Ph – (H-O-NR2) – H-O-O-R – H-O-F

    Let’s take a look at the pair HOMe – HOPh and HOPh – HOOH. In the first pair, the electronegativity difference is 2.8-2.5 = 0.3 and this, according to the Evans explanation, translates to ca 10^5 – 10^6-fold increase in Ka. For the latter pair, the electronegativity difference is much greater, 3.5 (O) – 2.8 (sp2 C) = 0.7, and accordingly hydrogen peroxide should be much more acidic than phenol.

    But it is not! The pKa of hydrogen peroxide is ca 11.5, it is in fact _less_ acidic than phenol.

    So something is wrong with the model. I would say the problem lies in not giving delocalization (”resonance”) the role it deserves.

  57. one in ten thousand Says:
    March 14th, 2007 at 7:52 pm Little things, like writing clearly, will make a difference. You’re asking a lot of your readers to have to decipher a poorly written paper. When it comes to demonstrating your competancy in science don’t excpect anyone to give you the benefit of the doubt…the same goes for seminars and lectures.The phenol issue reminds me of a similar debate concerning the acidity carboxylic-acids versus alcohols that was being fought in the literature more than a decade ago.
  58. excimer Says:
    March 14th, 2007 at 9:06 pm I noticed a grammar error in one of Grubbs’ recent Org Lett papers. Check Figure 4. Okay, yes, I AM guilty of putting Grubbs on a pedestal, but based on this and that Evan’s article I think it wise to place the blame on Org Lett’s copy editors and not necessarily on the original authors. Something like the error in Grubbs’ paper would not escape the omniscient eye of The Man.
  59. excimer Says:
    March 14th, 2007 at 9:08 pm I meant spelling error. (I suppose it could be construed as both…)
  60. Paul Says:
    March 14th, 2007 at 9:13 pm So you contend that there’s a rogue copy editor at Org. Lett. who’s inserting small grammatical errors into papers by big-name chemists? :O
  61. excimer Says:
    March 14th, 2007 at 10:53 pm No, I’m saying they’re not doing their jobs correctly. As some have pointed out, the blame might be more accurately placed upon the copy editors and not necessarily on the authors.
  62. Wolfie Says:
    March 14th, 2007 at 10:55 pm Beckmesser, Beckmesser, where are u going to ?
  63. Paul Says:
    March 14th, 2007 at 11:09 pm I see, so the authors don’t share the responsibility of correcting errors in the manuscript.
  64. Wolfie Says:
    March 14th, 2007 at 11:22 pm No, that’s why we have the language polishing service of Angewandte, or in case you have never published there, even in JACS. They catch your errors and don’t try to be much better than you.Share your responsibilities, Paul, and win. But, I admit, getting a Ph.D. is not about that.
  65. excimer Says:
    March 14th, 2007 at 11:59 pm Sure the authors have to share some of the blame, but the reason copy editors exist is to keep these problems from happening. Articles that come out with egregious/obvious errors are directly the fault of copy editors not doing their job- they are the last people to read the print before it goes to press. I don’t know how ACS Publications handle their copyediting process (hopefully I’ll get to find out soon…) but that’s how other forms of the press use copy editors. From Wikipedia:“The copy editor’s job may be summarized in the 5 Cs: to make the copy clear, correct, concise, comprehensible, and consistent. Copy editing typically entails correcting spelling, punctuation, grammatical and semantic errors; ensuring the typescript adheres to the publisher’s house style; adding standardized headers, footers, headlines and so on. ”If you want to place the blame directly on the authors, fine, part of it belongs there for not catching things like that themselves. But part of the blame belongs squarely on the journal themselves. The “Evan’s” mistake makes more than just the authors look bad- it makes the journal look bad, too- that’s one of the reasons copy editors exist, as a last line of defense, to save everyone’s ass from seething bloggers.
  66. Paul Says:
    March 15th, 2007 at 12:05 am I wonder if PJS and ABS3 are reading these posts.
  67. Beth Says:
    March 15th, 2007 at 12:21 am Why all the hating on the copy desk?I haven’t the foggiest idea how copyediting works at the journals (and we love our copy editors at C&EN), but copyeditors are often the journalism world’s equivalent of grad students : They work incredibly hard on tedious assignments, catching dumb mistakes that authors shouldn’t have made in the first place. No one notices or praises them for the 10,000 mistakes they did catch. But when they miss one little misplaced apostrophe in a sea of text, suddenly they’re not doing their jobs.Are copy editors really the most appropriate target for such vitriol?
  68. Wolfie Says:
    March 15th, 2007 at 12:27 am bla,bla,blathe matter is, if you have been a high school A+++ student and now at Harvard, Oxford, Heidelberg or anywhere, you need to learn what the world is really like
  69. Wolfie Says:
    March 15th, 2007 at 12:36 am Paul, just for the grammar, should I have said “alike”, or only “like” ??
  70. Paul Says:
    March 15th, 2007 at 12:41 am
  71. Wolfie Says:
    March 15th, 2007 at 12:42 am right you say
  72. Wolfie Says:
    March 15th, 2007 at 12:47 am you forgot the “a” in your comic, but yes, you are right !your English sounds like that of a Turk
  73. excimer Says:
    March 15th, 2007 at 1:06 am My intention certainly wasn’t vitriol, Beth. I have too many journalism major friends who would kill me for insulting that part of the job. It’s just reality, I guess- I’ve had discussions with journalism people who said, point-blank, if there’s a blatant problem with the output, it’s the copy editor’s fault. That’s just the reality as I’ve been told as it is. Of course, I object to making a big deal about it in the first place, but if you are, place it where it need be placed- on everyone who could have potentially fixed the error.I try hard not to be an asshole. Sometimes.
  74. excimer Says:
    March 15th, 2007 at 1:08 am Yeah, there were massive grammar foibles in that last comment. My bad.
  75. Wolfie Says:
    March 15th, 2007 at 1:15 am Paul, just for the theory, since you’re exposing yourself here so much, I assume you’re only a computer simulation, and have no soul. You cannot be real, otherwise you would get really angry.
  76. Paul Says:
    March 15th, 2007 at 1:28 am Don’t worry Ex, nobody proofreads stuff on the Internet.And Wolfie, you know that you’re my favorite commenter, right? It’s for the same reasons that Colonel Klink was my favorite character on Hogan’s Heroes.
  77. Wolfie Says:
    March 15th, 2007 at 1:34 am will have to think about that
  78. Paul Says:
    March 15th, 2007 at 1:39 am Here’s an episode on YouTube. Does Germany have color television yet?http://www.youtube.com/watch?v=1NZlex7SH6Y
  79. Wolfie Says:
    March 15th, 2007 at 1:57 am can’t watch it now, desert island has nothing like thattomorrow is another day
  80. Defender Says:
    March 15th, 2007 at 4:45 am To Wolfie,I have been noticing your concern for Paul’s Phd. Please understand, Wolfie, that (almost, I assume, w/hi-t/e sid/e-s cannot be an exception) every PI helps dumb students to get a PhD (and many papers), while they often accademically hostile to promising students. The fact of matter is that many of the former category students understand it very late, some never, like you because they became more dumber than their PhD days.
  81. Paul Says:
    March 15th, 2007 at 6:27 am Hey Beth: Tell the art staff at C&EN that the March 12th cover was very cleverly done. I loved the transparent title lettering against the Chinese flag. Subtle and cool.
  82. eugene Says:
    March 15th, 2007 at 12:33 pm “every PI helps dumb students to get a PhD (and many papers), while they often accademically hostile to promising students”Wow, that sucks. So he’s just being nice to me because I’m dumb and get results which produce papers. I’ve suspected it for a long time, but since I’m stupid, the realization was slow in coming. Thanks for the info though. Now I shall get my revenge…
  83. eugene Says:
    March 15th, 2007 at 4:37 pm Actually, this might sound arrogant, but you get exasperated when you talk to a piece of wood for a long time. So, I really doubt that ‘every PI helps dumb students get a PhD and many papers’. Unless they are masochistic. Which I guess, is what helps you get tenure. But no, most PIs help dumb students to get a Masters, would probably be a better statement. Then the dumb students have better job prospects as well. Go figure…
  84. Org Lett reader Says:
    March 16th, 2007 at 12:25 pm Hey Paul,One of the most storied labs in synthetic organic chemistry has done it again in Org Lett:http://dx.doi.org/10.1021/ol070163tThere’s a spelling error in the first paragraph that any spell-check would have caught, and on the second page a paragraph ends without a period.

    Super job!

  85. Paul Says:
    March 16th, 2007 at 2:27 pm Nice find. Once an accident…twice a coincidence…three times would be a trend.
  86. excimer Says:
    March 16th, 2007 at 3:10 pm See?!? My tinfoil hat and I were right! It is a conspiracy!!!!11oneone
  87. Wolfie Says:
    March 17th, 2007 at 7:37 pm “more dumber” must be the final word here
  88. cowboy chemist Says:
    March 23rd, 2007 at 2:01 pm Paul,Regarding typos in type-set publications: Most errors come from the type-setting and can be hard to catch in proof-reading. If you’ve written it and rewritten it, your mind knows the word is ‘stitch’ without processing the entire word printed as ‘stich’. Have someone new read it out loud to you while you look at the original, or even better read it backwards! Punctuation is still a problem if the reader is not good at it.You have to be careful about throwing stones at grammar. Most of us have glass windows if someone looks at them. My dissertation reading catches numerous dangling gerund phrases and incorrectly punctuated non-restrictive ‘which’ clauses. So I thought I’d check your publications! Here’s what I found:http://www.paulbracher.com/lab…..s/pub2.pdf

    “Using nitrogen-purged solutions, both fingerprints, namely, decay of CuP+¥ absorption at 660 nm and decay of C60 ¥- absorption at 1040 nm, reveal a decay time constant
    of 140……………”

    Dangling gerund. Fingerprints can’t use nitrogen-purged solutions.

    “FAB mass spectral data were obtained at the Michigan State University Mass Spectrometry Facility which is supported…………”

    Non-restrictive ‘which’ clause needs a comma unless MSU has a MS Facility that is not supported.


    “By changing the nature of the linkage between the ZnP and Cu(I)-phen moiety in the macrocyclic precursors to rotaxanes 2 and 3, the distance between the centers of positive and negative charge………”

    How did ‘distance’ change the nature of the linkage? Meaning is not mangled, but incorrect grammar!


    “(the other three meso positions are occupied by 3,5-di-tert-butylphenyl groups which improve solubility in common organic solvents…………”

    Needs a comma unless some 3,5-di-tert-butylphenyl groups do not improve solubility!

    “To date, no artificial system incorporating fullerenes has been reported which is able to accomplish the same objectives.”

    ‘which’ clause is dangling and not punctuated

    “The problem here is to synthesize molecular arrays analogous to 48 which can be unidirectionally inserted…………”

    Non-restrictive which clause needs a comma

    “Using ESFF and CVFF force fields, these observations [39] have been exactly reproduced computationally………”

    “Using techniques discussed in section 3.1, it was shown that (a) excitation of…………”

    “Using methodology adapted from that used by Maggini, Guldi and coworkers [75] to prepare analogous [Ru(bpy)3]2+ dyads, androstan-3-one was first linked to C60……”

    “Using varying applied DC voltages, the aniline–C60 dyad………”

    Four examples of dangling gerunds.

  89. Paul Says:
    March 23rd, 2007 at 3:37 pm Yup, you’re right. I have to say that George is the main reason my grammar has improved big time in grad school. When I read through some of the stuff I’ve written in the past (those three papers were from my undergrad days), I cringe at some of the mistakes. I find the errors (whether in grammar or bad style) like those you mentioned very embarrassing. There is no excuse for making them; you just admit you’re wrong and try to improve. I read through Strunk and White twice a year, cover-to-cover, and proofread things with care. While this is extreme, I think that too many people don’t give a damn at all.
  90. Wavefunction Says:
    March 23rd, 2007 at 5:36 pm Also very much worth reading “Eats, shoots and leaves” by Lynne Truss
  91. Hap Says:
    March 23rd, 2007 at 6:13 pm I knew someone who was on his twelveth(?) draft of a GMW paper. Large parts of the editing go towards experimental refinements and data needing to be acquired, but much of it is refinement in the writing and logic of the papers. If one writes enough papers with Prof. Whitesides, eventually some of the reasons for the editing and the rules underlying them will sink in. This would seem to be part of the job that professors are supposed to do – technical skills are more easily acquired (and more transient) than the ability to communicate ones’ work clearly and logically (and perhaps to work more logically as well).
  92. William Strunk Says:
    March 26th, 2007 at 2:01 pm Strunk and White (The Elements of Style) pretty clearly says it should be Evans’s and Grubbs’s (not Evans’ and Grubbs’) when referring to singular possessive.So when Paul wrote, “For those interested, these data come from Evans’ Chem 206 lecture notes” he was ironically just as bad as the original paper he was slamming (”the misplaced apostrophe in “Evan’s” was the most aggravating.”) The only people that get an exception to this rule are biblical (ie: Jesus’ and Moses’).Don’t get me wrong, Evans and Grubbs are good… but I’m not sure they deserve the biblical exception to the rule.
  93. Paul Says:
    March 26th, 2007 at 2:17 pm I was wondering whether anyone would bring up the letter of S&W’s law. My thought on the subject is that time passed them by. “Evans’s” looks and sounds stupid.
  94. Hap Says:
    March 26th, 2007 at 5:03 pm S+W makes a lot of sense – while the multiple Ss when the singular possessor has an s at the end of his name sounds stupid, the use of the possessive in that form readily differentiates singular possessives from plural possessives. The addition of another rule in possesives when people can barely distinguish between possessives and contractions on a consistent basis doesn’t make a whole lot of sense, particularly when it makes writing less clear as well.English is a hard language to justify anything by how well or badly it sounds, considering its less than consistent pronunciation rules.
  95. Phlogiston Says:
    March 27th, 2007 at 9:27 am I think that the Chicago Manual of Style, which is about 1000 times more definative than Strunk and White, states that nouns ending in “s” should simply add an apostrophe, e.g. Evans’ and never, ever Evans’s. An example they give follows from an answer to a question posted:Possessives and Attributives
    Q. A friend and I were looking at a poster that read “guys apartment.” I believe it should read “guys’ apartment.” She claims that it should read “guys’s apartment” and that the CMOS specifically gives the example of “guys’s” to make “guys” possessive. I looked through every section on possessives and did not find the word “guys’s” or any rule that would make this correct. Some people say “you guys’s apartment”—did I overlook the word “guys’s” as used in the attributive position? (I don’t think I did.)A. “Guys’s” is acceptable in the way that “youse guys” is acceptable; that is, neither is yet recognized as standard prose, and if your friend can find it in CMOS, I’ll eat my hat. Plural nouns that end in s (like “guys”) don’t add another s to form the possessive, e.g., the students’ lounge. “Guys’ apartment” is the standard spelling. If you want to make “guys” attributive, you can get away without the apostrophe, but you might test the idea with a plural noun that doesn’t end in s to see whether the attributive actually works: I doubt you’d write “the women apartment,” so you shouldn’t write “the guys apartment” either. And shame on your friend. It must make you wonder what else she’s capable of.http://www.chicagomanualofstyle.org/home.html
  96. eugene Says:
    March 27th, 2007 at 11:05 am “Some people say “you guys’s apartment””I believe almost every says it, not just some. Likewise, almost everyone will say “Evans’s”. However, it is not correct written form. The correct written form is “guys’ apartment”.Evan is just one guy, but his family has a lot of Evanses. So you would write, “I’m goin’ to the Evanses’ house to talk shop ’bout my lattest JACS comm with da tribe.”But if you were reading a JACS comm, where Evan was the senior author, you’d write, “I’m just knockin’ back a few while ab-sorbin’ some serious shit form da latest Evan’s JACS comm. Peace.”
  97. William Strunk Says:
    March 28th, 2007 at 4:16 pm I’m actually not sure if Eugene’s post was a joke… I don’t get jokes.For the sake of clarity: His name is David Evans (not Evan), and because it refers to a singular person it is a singular noun (as opposed to the plural noun: guys).I agree that you should not write or say “guys’s apartment.” However, you most certainly should write Evans’s (and Grubbs’s).
  98. Phlogiston Says:
    March 29th, 2007 at 10:10 am Strunk and White is out of date. CMOS does states the the rule also applies to names ending in s, thus the preferred spelling would be Evans’ not Evans’s (which just looks plain wrong anyways).
  99. Hap Says:
    March 29th, 2007 at 11:37 am Agaiin, relying on instinctive accounts of what looks and sounds right in English deosn’t make a whole lot of sense, considering the inconsistency of English pronunciation; when it makes content less logical, it doesn’t make any sense at all (which would not be completely inconsistent, but there you have it).
  100. Paul Says:
    March 29th, 2007 at 3:28 pm I think it does make some sense, because (to me) grammar is all about making sure that readers aren’t tripped up by the way you write. I think “Evans’s” will attract more unwanted attention than “Evans’” in a piece of writing, so I go with the latter.
  101. The Chem Blog » What’s the most acidic side group? Says:
    April 10th, 2007 at 5:02 pm […] The stability is found to be a result of internal hydrogen bonding – though I still don’t understand why the thiolate is the most stable. Though I’m as convinced their conclusions were interpreted correctly from their data, I’m not sold on the utility of such information. In water, the acidity is as you would expcet – the carboxylic acid terminus is the most acidic. Further, in cells, cystine seems to find a home in the hydrophobic interior of proteins (where a gas phase analysis may be more apt to predict behavior than an aqueous solution study) where they are involved in disulfide linkages – and needless to say, they do no see many exposed carboxylic acids. Though this paper did show me something interesting, which Paul may find cool, give his recent post on the pKa of phenol: […]
  102. boris the blade Says:
    April 12th, 2007 at 3:42 pm shame on you, complaining about this poor fellow’s language style… yet, good effort, wouldn’t have expected a north american (no offence intended to canadians of course) to be proficient in the English language to the extent of critisising someone else’s!


11 Responses to “I Judge People By Their Grammar and Knowledge of Phenol”

  1. Pittyswains Says:

    You’re a judgmental prick. Are you saying you can’t understand the article due to a misplaced apostrophe? Is it that catastrophic that you are unable to follow along? I could see if the grammar of the article followed street ebonics, but minor mistakes like that shouldn’t warrant such a butt hurt blog from you.

  2. Paul Bracher Says:

    I would recommend hyphenating your compound adjective “butt-hurt”.

  3. Genonema Says:

    This post reminds me of : http://en.wiktionary.org/wiki/grammar_Nazi

    Overall, liked your blog entries, btw.

  4. IAmTheWalrus Says:

    I’m with the folks advocating the Evans’s and Grubbs’s spelling.
    When ambiguity is possible, go for clarity, is what I’ve always read. Those spellings of singular plurals make it clear that the possessor is singular. Evans’ does not because English, unlike some other languages, pluralizes proper names by adding an s to them or an es for clarity or disambiguity (think “Keeping up with the Joneses” as opposed to “The Walter Whites of the world are its true tragic heroes” (see what I did there? I added es.)).
    Anyway, my personal logic is largely based on phonetics. Phonetically, there is no difference between “White’s” and “Whites”. Only context gives clarity. When you refer to a paper by Evans or Grubbs, you would actually be saying (Evan)z-iz paper or (Grub(b))z-iz, just as the neighbours you would be keeping up with would be the (Jone)z-iz. The added “iz” syllable makes it a possessive, not otherwise apparent, just as z sounds (blues) or softer s sounds (Blacks) added to familiar singulars indicate plurals.
    Yes, I can anticipate an objection: what about plural possessives? Is it Joneses’ and is it pronounced Jone-z-iz-iz? This would be a rare thing. If describing something attributed to all of the Joneses you are talking about, it is simplest and clearest to just label the thing without a possessive (“the Jones house”) whereas such may not be the case with a name not ending with s (“the White house”).

  5. IAmTheWalrus Says:

    However, I am really more interested in seeing replies to PMP’s very incisive comments.

  6. IAmTheWalrus Says:

    In particular, I teach that CH3OPh (pKa = 49) is not particularly more acidic than CH4 (pKa = low 50s, depending on source) (data in DMSO) in spite of being generated as intimately as possible with an electronegative element. This I attribute to lone-pair repulsions, because CH3SR and [CH3N(CH3)3]+ are 7 orders of magnitude more acidic than CHeOPh still (for both, pKa = 42 in DMSO). Similarly, CHF3 (pKa = 28) is *much* less acidic than CHCl3 (pKa 15.5) let alone CHBr3 (pKa = 13.7) (data extrapolated to H2O). It’s hard to find the data and, yeah, it’s counter-intuitive but, yeah, the data are out there. I conclude to my students that lone pair repulsions from electron density at neighbouring non-bonding orbitals in more similar valence shells (a through-space effect, in a way) strongly counteract inductive effects through bonding orbitals. That is essentially the same as negative (repulsive) hyperconjugation, which explains the preference in carbanions for less substituted vs more substituted ones carbons; substitution raises pKas (by up to 5-6 units, depending on sources for MeH vs EtH vs iPrH vs tBuH, or by up to 4 units by comparing MeOH and tBuOH) in spite of the increased electronegativity of C over H (which causes the downfield H-NMR shift from MeH to tBuH by some 1.5 ppm).
    Conclusion? resonance is really a strong factor in explaining the lower pKa values at allylic and benzylic positions.

    Yet increased substitution on the alkene portion of enols stabilizes enolates (as it does in alkenes).
    So I wrestle with the issue.

  7. Peter W Says:

    Re: Walrus’s comment on acidity

    This ends up being complicated due to incorrect assumptions having been made. Pauling assumed that bonds have covalent and ionic character. That assumption predicts ionic bonds can only be stronger than predicted from their covalent counterparts (Pauling in his 1932 paper). It is well known that metal hydrides are actually weaker. That should have been enough to discredit electronegativity theory. Simply, the haloacids, HF, HCl, HBr, and HI are good predictors of electron withdrawing properties. The acidity of the trihalomethanes follow that trend.

    Electronegativity theory is not based upon good science. This leads to a number of contradictions, just as noted. I have searched for examples in which fluorine is more electron withdrawing than the other halogens. Trifluoroacetic acid and the haloacetic acids are the model generally cited. However, if substituted acetic acids are compared, their acidity does not correspond with electronegativity predictions. Hydrogen is more electron withdrawing than carbon. A less substituted anion will be less basic. It is the fault of electronegativity theory to expect the opposite.

    I agree the increase in phenol’s acidity is due to an inductive effect. I never liked using the product of a reaction to explain why it should take place in lieu of discussing the intrinsic reactivity of the reagents. Acetone and its enol have the same resonance anion, but simple logic should lead one to anticipate oxygen (greater nuclear charge) to be more electron withdrawing and the enol more acidic.

  8. Roseanne Says:

    Se você realmente deseja um PENIS MAIOR, DEVE fazer esses
    exercícios, de acordo com as instruções.

  9. Del Says:

    É muito importante respeitarmos os limites do nosso corpo e não agir com
    muito radicalismo.

  10. Fawn Says:

    What’s more, laser cataract surgery with the Catalys laser system now brings a
    new level of accuracy to the cataract procedure itself, and many patients are back
    to normal activities within days following the procedure.

  11. Mckinley Says:

    Mettez au menu de chaque repas des légumes, aliments
    de grains entiers ou autres féculents et aliments riches en protéines.

Leave a Reply