Talk:Ester

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carbonyl required??[edit]

The first sentence states that esters require a carbonyl, and the article later discusses consequent bond angle implications, but also lists phosphoric acid ether as an example of an inorganic ester. This seems like a contradiction. Can it be addressed more directly? — Preceding unsigned comment added by 128.112.160.140 (talk) 19:57, 16 February 2014 (UTC)

Clarified RomanHunt (talk) 06:37, 29 June 2014 (UTC)

In chemistry, esters are classes of chemical compounds. Esters are usually derived from an inorganic acid or organic acid in which at least one -OH (hydroxyl) group is replaced by an -O-alkyl (alkoxy) group.[1] Commonly esters are derived from carboxylic acids and alcohol.
These statements are vague and overlapping. Can somebody sharpen it up?
Okay, I rewrote it a less wobbly but I don't know enough to resolve the remaining ambiguity (or inaccuracy if I've made it worse). 84.227.252.224 (talk) 18:06, 14 October 2014 (UTC)
I fixed a new problem that was introduced (the general first sentence was generalized beyond the actual definition prior to being more correctly limited in the next sentence). DMacks (talk) 05:16, 15 October 2014 (UTC)
Now I am confused again. The first two sentences of the article:
In chemistry, esters are chemical compounds derived from an inorganic acid or organic acid in which at least one -OH (hydroxyl) group is replaced by an -O-alkyl (alkoxy) group. Esters are generally derived from a carboxylic acid and an alcohol.
(a) I find the first sentence confusing now. It is more technical-sounding and computational than I would like. Alternately, staying technical but making it more precise, maybe it would help to write "...in which one or more -OH (hydroxyl) groups of the acid are replaced with...
Reason why I like "one or more" : it brings multiple replacements to the mind a bit more vividly.
Reason I like "of the acid" : not all acids have an OH, so the non-chemist tends to mentally locate the OH in the alcohol molecule, which then makes no sense. And I suppose the intention is that an acid can only make an ester if it already has OH groups. Is this correct?
(b) Are the first and second sentences really consistent? In the first sentence, the alcohol-thing is OH plus an alkyl, whereas in the second one, the alcohol-thing is any alcohol.
Perhaps the problem is that the second sentence is phrased as if it is re-doing the definition. If there is no intention to change the class of alcohols, then perhaps the second sentence should read: "The acid is generally a carboxylic acid." But then I wonder if the normative "generally" should actually be replaced by "often". If the intention is that the first sentence give the structure and the second sentence indicate how it is made, then the first sentence perhaps should not use the verb "derived" and should avoid the active metaphor of "replaced by".
Also I was confused by the mention of ethylene glycol as the alcohol in an example in the "inorganic esters" paragraph, it seems to contradict the O-alkyl group requirement of sentence one, but is consistent with sentence two. The mention of nitroglycerin is even more confusing. It doesn't seem to match the picture in sentence one, which in its precision doesn't seem to allow for a geometry of multiple acid pieces connecting to the same central alkyl group (minus a few more hydrogens). Note that in the nitrate ester article, we have the definition A nitrate ester is the organic functional group with the formula RONO2, where R stands for any organic residue. I assume that a nitrate ester is supposed to be an ester, but I have no idea how general an "organic residue" is.
I can't do any of these changes myself because I don't know the chemistry.
(84.227.252.224 again) 84.226.161.234 (talk) 00:03, 21 October 2014 (UTC)

Typo ?[edit]

I'm not sure, but i guess 'Esters are more polar than ethers but less polar than alcohols' should be replaced by 'Esters are more polar than acids but less polar than alcohols' ? — Preceding unsigned comment added by 121.1.55.84 (talk) 00:57, 2 October 2013 (UTC)

It is correct as written. RomanHunt (talk) 06:36, 29 June 2014 (UTC)

Listing[edit]

Do we indeed really need to mention a whole list of esters? The chemistry section is much more important. There are not even mechanisms in there that explain the acid cat. ester formation! Sikkema 12:30, 20 July 2007 (UTC)

I think the ester_compound page should be moved back here. The other pages are not as important as the chemistry one, except for the ester, alaska one but a note at the top of the page would suffice for that. Ester final fantasy is trivial and esther i the bible is not even the same spelling. Its not called an ester compound anyway, if anything it should just be ester (chemistry). Borb 08:28, 6 May 2005 (UTC)

I think the list is a great idea. I just recently ran into an unknown ester where all I had to go on is the smell, and this list was a good reference. Just saying. -Courtney —Preceding unsigned comment added by 69.152.216.24 (talk) 22:10, 9 June 2010 (UTC)


It might do to describe which isomer of the pentyl radicals are refered to in some of the esters given.

  • Given that one-carbon differences in chain length lead to distinguishable

odors, and that different optical isomers of odorants/flavorants (eg, carvone) lead to distinguishable odors, I would be *very* surprised if there were not also a dependency on pentyl chain isomerism.


Could anyone explain how the term mono-ester and di-ester is used?

  • This page needs a bit on mono, di and poly esters (I linked it to polyester page already, but thats also not very good). Basically a monoester is just an ester (one ester) a di-ester is two esters bonded together (the same way as polyesters).

Chemical properties[edit]

I was frustrated by the lack of information on the chemical properties of esters. Are the reactions listed the only ones that it usually goes through? Could someone please post more information?

The reaction(s) listed are not the only ones esters can undergo. A discussion of all the reactions esters can be involved in can fill up an entire chapter of an organic chemistry book. It's not practical to list them all in a general encyclopedia. Some day, when I have time, I might do some work on this esters article. H Padleckas 09:19, 10 Dec 2004 (UTC)
Some of the previous few edits, including mine, have improved this article - especially the definition of ester (needed to encompass inorganic acid esters), but some day I would like to do still more to improve this article. H Padleckas 08:47, 14 July 2005 (UTC)
I'll get some info up in the future.
The methyl acetate link points to the article, but the article says that the compound has an odor of glue, which conflicts with the table, where it is listed as having the odor of peppermint. Anybody know which needs fixed?
Methyl acetate smells of modelling glue, MENTHYL Acetate smells of peppermint! —Preceding unsigned comment added by Strontiumred (talkcontribs) 14:30, 16 October 2007 (UTC)

move ester compound back?[edit]

yes, the ester content did move to ester compound because other ester (esther) definitions started to pop up. feel free though to revert this edit back to the original but please consider a solution for the other definitions.

Methyl butanoate and Ethyl butanoate[edit]

I started researching the net to verify that methyl butanoate and ethyl butanoate both have a pineapple smell. Here is what I found up this time:

  • [1] says that both methyl butanoate and ethyl butanoate smell of pineapple.
  • [2] lists ethyl butanoate under pineapple.
  • [3] says that ethyl butanoate is pineapple [flavor].
  • [4] says that methyl butanoate is apple [flavor] and ethyl butanoate is pineapple [flavor].
  • [5] says that methyl butanoate smells of pineapple.

Based on these findings and for consistency with the rest of Wikipedia, I edited the list under the Physicals section of the Ester article to state the methyl butanoate smells of pineapple or apple and ethyl butanoate smells of pineapple. It's certainly possible for very similar compounds to have similar smells. A pineapple does not necessarily have to be flavored with only a single compound. H Padleckas 16:37, 17 July 2005 (UTC)

Ester who?[edit]

Can anyone add the explanation or story behind the name? I'm not sure, maybe I'm mixing with another compound name, but I've heard about some compound named after the lover of the chemist who've discovered it. Is this the same compound?—Preceding unsigned comment added by Cow2001 (talkcontribs)

It might be easier if you had links that actually showed the structure.—Preceding unsigned comment added by 65.27.132.105 (talk)


"Esters are a class of chemical compounds and functional groups."

This definition is unsat. Needs to distinguish esters from other chem compounds and functional groups.

Norm

Nomenclature[edit]

If anyone has the rules handy (I don't right now), a description of the IUPAC method for naming esters would be handy. 24.118.220.84 06:36, 5 May 2004 (UTC)

Agreed. Not to mention the inclusion of naming esters as substituents.134.250.70.81 02:45, 22 February 2007 (UTC)

There has just (22-23 Nov 2009) been a flurry of changes to the nomenclature example - hexyl octanoate. I think these may have been triggered by the long-standing mis-link, which, although to the correct acid - caprylic acid (C8), was labeled as "caproate", which referes to caproic acid (C6). I have changed the label from "caproic" to "caprylic", and returned the formula to the standard form, as described in the following paragraph in the main article, with the acid, terminating in CO2, followed by the alcohol (which reverses the order in the name, adding to the confusion).FredV (talk) 16:27, 23 November 2009 (UTC)

Intro Too Technical[edit]


69.140.164.142 13:12, 6 April 2007 (UTC)

Hey, the last paragraph of the intro had some good layman info. I'm moving it up to the front and simplifying it.

ok so now the intro is like: esters=important. several layman examples: dna, nitroglycerin, poly-ester (bells ring in head). Then, slightly more technical description. Then etymology. Then the really technical description, which I mostly didn't touch. How's that? How does the 'too technical' banner get removed?

Guidelines say that the first parag of intro should 'define' and set scope of word. I know that listing several examples of an 'important compound' is a poor substitute, but I couldn't come up with a nontechnical way to say it all without introducing more technical terms like 'alcohol' (you mean like booze?) or 'acid' (you mean like LSD?).

OsamaBinLogin (talk) 20:38, 15 March 2009 (UTC)

Fatty acids and glycerol[edit]

It looks like someone moved it back. The term "fatty acid esters of glycerol" does not tell me how fatty acids relate to glycerol - they are totally different, glycerol has a higher oxygen ratio and is shorter, for example. will have to look elsewhere. Triglyceride seems to provide a little more information Charlieb000 (talk) 02:54, 19 May 2013 (UTC)

If you connect a fatty acid (which is a carboxylic acid) to glycerol (which is an alcohol), the linkage is an ester. Thus, the produce is a "fatty acid ester of glycerol". Diacylglycerol would be an example. -- Scray (talk) 03:34, 19 May 2013 (UTC)

Table[edit]

I started cleaning up the big table. In particular, I made it sortable and added images and molar masses. It would be interesting to also have the NFPA 704 health, flammability, and reactivity numbers as their own (sortable) column. —Ben FrantzDale 22:13, 13 May 2007 (UTC)

Diamonds do not show in all browsers[edit]

Red/blue/yellow diamond shapes do not display properly in all browsers. They could be replaced with a similar symbol from under the edit box, but the size would have to be specified as well. For example:

Svemir 14:28, 16 May 2007 (UTC)

Very vague intro[edit]

This article is too vague for those with little chemistry knowledge. The introduction doesn't explicitly explain what an ester is in terms of what atom connects to what. The introduction is poorly written--it merely lists the types of esters out there. Too much details but no actual description of what an ester is specifically. (Compare this article to the Carbonyl article. The other article's first sentence concretely tells about the atom-atom connections: "In organic chemistry, a carbonyl group is a functional group composed of a carbon atom double-bonded to an oxygen atom : C=O.199.76.186.8 03:55, 8 September 2007 (UTC)

Better? Cacycle 04:54, 8 September 2007 (UTC)

Thank you![edit]

This is just to say thankyou to those who edit and make sure this and related articles are acurate and easy to understand, as I'm sure you realise many students such as myslef go to chemistry articles like this to learn. Thank you. —Preceding unsigned comment added by 217.35.93.92 (talk) 19:39, 19 March 2008 (UTC)

Odours[edit]

According to Twenty First Century Science GCSE Chemistry (ISBN: 978-0-19-915050-2), pineapple contains 120mg/kg of ethyl ethanoate (or ethyl acetate as in this article). Should pineapple be included in the table of odours for ethyl acetate? Leonini (talk) 11:55, 22 May 2008 (UTC)

Replacing the OH with an O in an acid.[edit]

I must say that I don't remember too much from my college chem courses, but do alot of acids have OH groups? I thought that's what made a base. Smack me if I'm wrong. Alex T 69.122.62.231 (talk) 02:28, 29 May 2008 (UTC)

This is not the place for an essay on the definitions of acids and bases, but the following summary might help. Basic school chemistry usually defines acids as compounds that can donate H+ ions, and bases as compounds that can accept H+ ions (the Brønsted-Lowry theory). One of the common classes of bases (the alkalis) do indeed include the -OH (hydroxyl) group (a standard example being sodium hydroxide - NaOH). However, many acids also contain -OH groups: sulphuric acid (H2SO4) has the structure HO-(SO2)-OH, with two -OH groups, and phosphoric acid (H3PO4) has three -OH groups. The key difference is how they ionise (typically in aqueous solution): a base B-OH will typicall ionise to B+ + OH-, while an acid A-OH will ionise to A-O- + H+. I hope this helps! (and yes, that is how we spell "ionise" in the UK). FredV (talk) 11:30, 7 January 2009 (UTC)

Half ester[edit]

What is a half ester? If this is the place to explain, someone please go ahead.
Thanks, ... PeterEasthope (talk) 22:13, 17 November 2008 (UTC)

I am not an expert, but I believe this rather confusing term is used to describe derivatives of dicarboxylic acids (i.e. R(CO2H)2) in which only one of the acid groups is esterified (i.e. R(CO2H)CO2R')FredV (talk) 12:10, 13 January 2009 (UTC)

Oligoesters[edit]

I am revising the article following the outline in the Chem manual of style. Large chunks will be moved around. This particular piece seems out of place somehow, sort of a game on who can name high-order oligoesters. For an overview, these species seem to be rather specializes, but I did not want to unilaterally discard this info. I retained (and will expand) the triester bit, since the triglycerides are so broadly important.--Smokefoot (talk) 05:39, 27 August 2009 (UTC)

Oligoesters[edit]

Polyester polymer containing a small number of component esters.

Tetraesters can be found as part of membrane-spanning lipids in bacteria from the order Thermotogales.[1]

Hexaesters such as calix[6]arene have been used in optodes as sensing devices for optical determination of potassium ion concentration in pH-buffer solutions.[2]

Heptaesters have been found in Euphorbia species.[3]

Octaesters can be inclusions of ester moieties within cavitand cavities.[4]

The number of esters can be up to ten as in oligo-(R)-3-hydroxybutyrate[5].

References

  1. ^ Damsté JS, Rijpstra WI, Hopmans EC, Schouten S, Balk M, Stams AJ (December 2007). "Structural characterization of diabolic acid-based tetraester, tetraether and mixed ether/ester, membrane-spanning lipids of bacteria from the order Thermotogales". Arch Microbiol. 188 (6): 629–41. doi:10.1007/s00203-007-0284-z. PMID 17643227. 
  2. ^ Chan WH, Lee AW, Kwong DW, Tam WL, Wang KM (April 1996). "Potassium ion-selective optodes based on the calix[6]arene hexaester and application in human serum assay". Analyst. 121 (4): 531–4. doi:10.1039/an9962100531. PMID 8633794. 
  3. ^ Evanics F, Hohmann J, Rédei D, Vasas A, Günther G, Dombi G (October 2001). "[New diterpene polyesters isolated from Hungarian Euphorbia species] [Article in Hungarian]". Acta Pharm Hung. 71 (3): 289–92. PMID 11961895. 
  4. ^ Dueno EE, Bisht KS (April 2004). "Intramolecular inclusion in novel octaester cavitands". Chem Commun (Camb). (8): 954–5. doi:10.1039/b316498e. PMID 15069491. 
  5. ^ Xian M, Fuerst MM, Shabalin Y, Reusch RN (November 2007). "Sorting signal of Escherichia coli OmpA is modified by oligo-(R)-3-hydroxybutyrate". Biochim Biophys Acta. 1768 (11): 2660–6. doi:10.1016/j.bbamem.2007.06.019. PMID 17659252. 

Merge proposal[edit]

I think that this merge should be noncontroversial. Under the manual of style for functional groups, the article ester is required to have a section on their preparation. The main method for their preparation is esterification, so it seems that this as a separate article should be blended with this one. Ideas welcome.--Smokefoot (talk) 03:17, 7 November 2010 (UTC)

Don't think it's controversial either. We have lots of material in ester already, I think you can just salvage whatever has not already been mentioned here from esterification, and redirect it here. --Rifleman 82 (talk) 04:05, 7 November 2010 (UTC)

Appendix A: Ambiguity[edit]

The Table in Appendix A that provides a list of Ethers has one column labeled "Odor or occurrence" which makes the listing of substances ambiguous as to whether the ether smells like the substance or is found as a component of the substance. Alchemy Heels I (talk) 18:50, 24 November 2010 (UTC)

Toxicity[edit]

Thanks for the great article. I was however looking for a toxicity topic and did not see it (did I miss it?). Specifically with regards to alcoholic beverages, someone once told me that a reason for maturing spirits using oak wood is because undesirable (toxic?) esters will either evaporate through the oak microscopic pores or complete their chemical transformation into alcohol over the maturation period. Is this true? — Preceding unsigned comment added by Robertoff (talkcontribs) 02:34, 21 July 2012 (UTC)

Putative contradiction[edit]

In this edit a contradiction is claimed by Anypodetos, i.e. "The first sentence only includes carboxylates, while the next two include derivatives of any oxo acid. The ref (Gold Book also includes thioesters etc.)," but I don't see it. I am not an expert so I may have misunderstood - please explain. The first sentence (referenced in the claim) does not refer to a carboxylic acid at all; rather, it refers to a carbonyl group, which does not assume that the carbonyl came from a carboxylic acid (i.e. it could come from an oxoacid, which is what the next two sentences specify). -- Scray (talk) 20:39, 11 December 2013 (UTC)

The first sentence refers to a carbonyl (C=O) neighbouring an ether (–O–), which together would make up a carboxylic acid group. Other oxoacids (such as sulfuric acid) don't have a carbonyl. The Gold Book (Ref 1) first talks about carboxylate esters, and then mentions other esters "by extension", whatever that means. --ἀνυπόδητος (talk) 12:58, 12 December 2013 (UTC)

Structures needed[edit]

Just a request - I think the article, especially the preparation section, needs more structures instead of inline molecular formulas. It would increase the readability a lot. OxygenBlue (talk) 21:55, 16 December 2013 (UTC)

Changed lede[edit]

This lede had been bothering me for awhile. I made 3 changes. For me, it's a great improvement, but I have two questions.

(1) New version: Usually, esters are derived from a carboxylic acid and an alcohol.

Should it be "usually" or "often"? Or qualified with "organic" or something?

(2) New version: Esters comprise most naturally occurring fats and oils. An important case are glycerides, which are fatty acid esters of glycerol.

Would "triglycerides" match better than "glycerides" with naturally occurring fats and oils?

What really is the relationship between "naturally occurring fats and oils", and various glycerides? Is it overlap, inclusion in one direction or another, or synonymy?

I apologize for editing (2) without knowing the relationship. But the prior version was esters comprise most naturally occurring fats and oils, which are fatty acid esters of glycerol. This is confusing, perhaps even self-contradictory. Does it say "esters encompass most fatty acid esters of glycerol" or "esters account for most fatty acid esters of glycerol"? In any case, it seems to contain a definition and an empirical statement about prevalence wrapped up too closely together.

The word "comprise" can be problematic, unless the direction of inclusion is crystal-clear from context. The word is truly ambiguous as to what is a subset of what !! By Google:

(1) Consist of; be made up of. "The country comprises twenty states." Synonyms: consist of, be made up of, be composed of, contain, encompass, incorporate.

(2) Make up; constitute. "This single breed comprises 50 percent of the Swiss cattle population." "This breed comprises half the herd". Synonyms: make up, constitute, form, compose; account for.

Remarkably, neither reading seems to function correctly in the original version of (2). 89.217.9.188 (talk) 02:44, 17 January 2015 (UTC)

Esters comprise most naturally occurring fats and oils.
Okay, I've learned (from Wikipedia) that "oils" is a large, loosely defined, diverse group defined by sensible properties as much as by chemical make-up or origin. They include fatty acids, steroids, proteins, waxes (when melted), alkaloids, glycerides, long-chain alcohols, hydrocarbons, etc (see oil, lipid, wax and linked articles therein) . In particular "naturally occurring oils" must also include petroleum-derived oils. Of these, I would say that while many are esters, many others are not. So this statement can't be right as it stands, but perhaps should be qualified with "occurring in metabolism", "made by organisms", or "pervasive in biochemistry" to make true. 178.38.85.238 (talk) 18:27, 18 January 2015 (UTC)
I've changed "Esters comprise most naturally occurring fats and oils.[dubious – discuss] An important case are glycerides, which are fatty acid esters of glycerol." to "Glycerides, which are fatty acid esters of glycerol, are important esters in biology, being one of the main classes of lipids, and making up the bulk of animal fats and vegetable oils." Seems good enough to me. User:GKFXtalk 19:41, 27 May 2015 (UTC)