Questions tagged [esters]

For questions about the synthesis, properties, and reactions of ester compounds, both organic and inorganic.

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20
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4answers
2k views

During the development of aspartame, why was the methyl ester chosen?

One frequent argument against the safety of the synthetic sweetener aspartame is that it can be hydrolyzed, with one of the hydrolysis products being methanol, which is known to be toxic. Of course, ...
17
votes
1answer
4k views

Why are lactones more acidic than esters?

Lactones ($\mathrm pK_\mathrm a \sim 25$) tend to be more acidic than esters ($\mathrm pK_\mathrm a \sim 30$). I know that the lactone is fixed in a (E)-conformation, due to the ring: and that in ...
13
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2answers
37k views

Why do esters actually smell?

We all know the very famous esterification reaction, where a carboxylic acid and an alcohol react to give an ester and water. But why do they actually smell? What is the reason behind its aromatic ...
13
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2answers
9k views

Resonance stability: ester vs. thioester

My problem set solution cites: "Although sulfur is less electronegative than oxygen, overlap is a more important consideration. Sulfur is a member of the third period. As a consequence, a ...
12
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1answer
396 views

Unusual hydrolysis of methyl 2,4,6‐trimethylbenzoate

Problem 223 from Conceptual Problems in Organic Chemsitry by Singh [1, p. 367]: The given answer is b and I don't get why. Usual ester hydrolysis would've given a. I somehow managed to know that the ...
11
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1answer
21k views

Mechanism for formation of amide by reaction of amine with ester

This is the mechanism given in my lecture handout: I have a problem with the third species along. Surely the negatively charged oxygen would protonate before the other oxygen would. Also, why does ...
11
votes
1answer
256 views

Which electronic effects are responsible for the reduction of nucleophilicity of a hydroxy group orthogonal to an ester?

I am facing a similar synthetic problem as Boekman Jr. et al noted in their synthesis of Tetronolide.[1] I will quote their’s rather than disclosing my actual synthetic problem, but note that the key ...
10
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2answers
906 views

What is the name origin of ester?

Ester is quite a random nomenclature for a compound derived from a parent acid and parent alcohol. Is there any reasoning behind using the word 'ester' to name such compound (for memorising purpose)? ...
9
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2answers
1k views

Why are peroxides unstable but disulfide bridges considered stable? Why are esters stable but thiolesters are unstable?

I can not understand why a peroxide $\ce{R-O-O-R}$ is considered reactive and unstable. Going down one row on the periodic table, a disulfide bridge ($\ce{R-S-S-R}$) is apparently super stable and ...
8
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1answer
5k views

Is it possible to oxidize ether to ester?

Is it possible to synthesize an ester from an ether in a single step? For example if I had an ether $\ce{(R-CH2-OR')}$, can I oxidize it so it will be an ester $\ce{(R-CO-OR')}$.
8
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1answer
276 views

How can rotamers of alpha-keto esters be named to distinguish between different geometries?

When talking about free rotation it is often helpful to determine about which geometric arrangement one is referring to. For example in the case of butane we talk about several eclipsed or staggered ...
8
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1answer
346 views

No chlorate esters? Why?

Why are there no chlorate esters? Or are they just undocumented or too unstable? I've seen perchlorate esters, but google "chlorate esters" and only perchlorate esters come up.
7
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2answers
915 views

Choice of base for malonic ester synthesis

Most reaction mechanisms use $\ce{EtO-}$ as a base to deprotonate the alpha hydrogen in the malonic ester sythesis. But in the equilibrium there are still esters that haven't been deprotonated. Why ...
7
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2answers
617 views

Why can you not make a compound with a quaternary alpha carbon using malonic ester?

So my textbook tells me that using a malonic ester to make a quaternary alpha carbon is impossible (I get that this might be hyperbole). However, it doesn't explain why and I don't understand why. ...
7
votes
1answer
513 views

What is the name of this ester?

Can you tell me the name of this ester? It is two $\ce{C8}$ fatty acids ester-linked with a molecule of 1,3-butanediol in the middle. I would be tempted to say (R)-butanediol-1,3-diyl dihexanoate, but ...
7
votes
2answers
604 views

Retrosynthesis of a lactone

We have been asked to do a retrosynthesis of (6⁠S)-6-[(2⁠S)-2-hydroxy-4-phenylbutyl]oxan-2-one J from 3-phenylpropan-1-ol K: My first instinct would be to do a functional group interconversion of the ...
6
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1answer
2k views

Finding the mystery ester strucuture using NMR

I have an unknown ester with the chemical formula $\ce{C9H10O2}$ that is used as a flavoring agent in candies. It exhibits the following H-NMR and C-NMR (Attached file: unknown ester NMR) Based on ...
6
votes
2answers
721 views

How is the configuration of an ester enolate double bond assigned according to CIP?

Two principal modern methods for enantioselective aldol reactions — the Evans aldol and the Masamune aldol — use a carboxylic-acid derived enolate rather than a ketone enolate as e.g. in the Paterson ...
6
votes
1answer
4k views

Protonation of ketone and ester

If there is a ketone and ester functional group in the same compound and I want to protonate with $\ce{HCl}$, which one will protonate first? Is it the carbonyl group in the ketone or the carbonyl ...
6
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1answer
2k views

How many grams of each substance will be present at equilibrium in the reaction of ethanol and ethanoic acid?

In the following reaction, $K_c=4.0$: $$\ce{C2H5OH + CH3COOH <=> CH3COOC2H5 + H2O}$$ A reaction is allowed to occur in a mixture of $\pu{17.2 g}$ $\ce{C2H5OH}$, $\pu{23.8 g}$ $\ce{CH3COOH}...
6
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1answer
234 views

Electrophilicities of carboxylic acid derivatives

I would like to ask about the rate of hydrolysis for 4-hydroxyphenyl acetate (A), N-(4-hydroxyphenyl)acetamide (B), 4-hydroxyphenyl chloroacetate (C), and methyl 4-hydroxybenzoate (D). I know that ...
5
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2answers
6k views

Reaction of Grignard reagents with esters

Suppose I have a phenyl Grignard and methyl benzoate. If I react the two, can I expect benzophenone and a triphenylmethoxide ion as my products? I ask because I know that Grignards react with ...
5
votes
1answer
667 views

Does the Dieckmann Reaction proceed via the conjugated enolate of the product?

In the following mechanism of the Dieckmann Condensation, the product has been formed in the fourth step, but still the reaction proceeds and $ \ce{RO^{-}}$deprotonates the product. Then $\ce{H^{+}}$ ...
5
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1answer
13k views

Sulphuric Acid in Esterification Reaction

Why is it that adding the sulphuric acid slowly to a solution of alcohol and carboxylic acid (making an ester) will increase the yield of the product? It seems that not only does the rate at which it ...
5
votes
1answer
545 views

Is Nitroglycerine a Nitro Compound or an Ester?

I looked up nitroglycerine in a science dictionary (Oxford Dictionary of Science, 2003), and it explicitly mentions that nitroglycerine is an ester and not a nitro compound. However my teacher told ...
5
votes
2answers
859 views

How to esterify phenol with oxalic acid?

Is it possible to fully esterify phenol with oxalic acid in order to get diphenyl oxalate? What catalyst should I use and is the synthesis possible to perform at home with hobby equipment?
5
votes
1answer
357 views

Can citric acid create a polyester?

Citric acid has both alcohol and carboxylic acid groups, so could it "esterify" with the other citric acid molecules in solution? I notice that it is a tertiary alcohol. I don't suppose that would ...
5
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0answers
99 views

Interaction of trifluoroacetates with acetylcholinesterase

There exists a substance called TMTFA, or 3-(N,N,N-Trimethylammonio)-2,2,2-trifluoroacetophenone. It is known for being able to inhibit acetylcholinesterase at femtomolar concentrations. The TMTFA-...
5
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0answers
100 views

The IUPAC name of a multifunctional carboxylic acid compound

What is more preferred name when ester is present as junior functional group bis-carboxylic acid? (refer the image attached): to count carbon of ester and consider two branches on it (one oxo and ...
5
votes
1answer
3k views

Protonation of Carbonyl oxygen in Fischer Esterification

In the Fischer Esterification, why is it the acid's carbonyl oxygen getting protonated and not the hydroxyl oxygen? This protonation occurs in Step 1 of the mechanism below. I read in some textbooks ...
4
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2answers
262 views

Are there amide versions of lactides and lactones?

In my book, I read that Lactides and lactones are cyclic esters which contain two and one ester group in them, respectively. They are formed when $\alpha$-hydroxy; and $\gamma$- or $\delta$- hydroxy ...
4
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2answers
1k views

Which side of the C-O-C bond breaks in esters during hydrolysis in basic medium?

When an ester undergoes hydrolysis which side of the $\ce{C-O-C}$ breaks for instance in the following example: I believe the first is correct but is it a rule that the salt of a carboxylic acid is ...
4
votes
2answers
151 views

How does this brominated intermediate lose its methyl group?

The problem is such: So far my working has been: I'm concerned about the last step where the ester forms a ring. The methyl group doesn't look like a plausible leaving group, but it does not ...
4
votes
2answers
262 views

Can the alkyl-oxygen bond in lactones be cleaved in an SN2 reaction?

I understand that nucleophiles typically attack the electrophilic carbonyl carbon of the lactone and open the ring through a nucleophilic acyl substitution. Has there ever been the case where the ...
4
votes
1answer
465 views

Naming of ester alkoxide

I'm trying to name the following compound: I believe the carboxyl group has priority and should make up the parent name. I'm not sure how to name the alcohol derivative portion. My first thought is: ...
4
votes
1answer
113 views

How would I go about making an ethyl ester from vegetable oil?

I'm teaching myself how to make lotion and a lot of lotions contain esters like isopropyl myristate or isopropyl palmitate. I'd like to make an ethyl ester from a popular skin-care oil (olive, apricot ...
4
votes
1answer
337 views

Formation of methyl esters

Can't we perform Fischer esterification using methanol to make a methyl ester from a carboxylic acid? If so, why might we use diazomethane? Would the release of nitrogen gas confer an entropic ...
4
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1answer
3k views

Are all esterification reactions reversible? What is their general mechanism?

For example the reaction of ethanoic acid with ethanol is reversible, however is this true for all esters? I'm not quite whether it is as easy for a reversible reaction to occur both ways. Is there a ...
4
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1answer
416 views

Deciding more electrophilic centre between ester and thioester for SN type reaction

My question: (though it won't alter the product) Which carbon is attacked first, the one adjacent to sulphur or the one adjacent to oxygen? The solution says that the carbon adjacent to sulphur is ...
4
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1answer
153 views

Why does a carbonyl reform in ester reactions

I have noticed that frequently whenever esters react with a nucleophile, the nucleophile will attack the carbonyl carbon and eventually in order for the carbonyl to reform the other oxygen will leave ...
4
votes
1answer
236 views

Mechanism of Acid Hydrolysis

I wanted to ask a question about acid catalysed hydrolysis. I learnt in an introductory course to Physical Organic Chemistry that there are different ways that an ester can be hydrolysed acidically: ...
4
votes
1answer
399 views

Hydrolysis of an ester

An organic compound X of formula $\ce{C5H10O2}$ forms two compounds when boiled in aqueous sodium hydroxide solution. One of these compounds forms a ketone when treated with acidified potassium ...
3
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1answer
12k views

What is the difference between the esterification and transesterification?

What is the difference between an esterification and a transesterification. Esterification objective is the formation of an ester by reacting an alcohol and a carboxylic acid. I am more concerned ...
3
votes
1answer
746 views

Why aqueous hydroxide is slippery (beyond just saponification)

A recent question mentions: Bases are soapy to touch because of soap formation on contact with lipids present on our skin. This is always the reasoning I hear, as well, and searching the internet ...
3
votes
1answer
1k views

What type of polyester is most commonly used for clothing?

Many polymers have the name of the monomer in their names, e.g. polyethylene, polyvinyl chloride, polypropylene, polystyrene etc. But the ester in polyester refers to a group of chemicals (having an ...
3
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1answer
3k views

Failed esterification of 1-butanol and ethanoic acid

I did an esterification experiment of 1-butanol and ethanoic acid. 30 mL of 1-butanol was added followed by 30 mL of ethanoic acid, and then 1.5 mL of concentrated sulphuric acid and some boiling ...
3
votes
1answer
167 views

Mechanism for the intra-molecular exchange of an ester and a nitrile group

When the isolated product 4 is treated with sodium ethoxide in ethanol it rearranges to 5 as shown: My TA says that you need to start with a reverse Claisen at the ketone but I am not quite sure ...
3
votes
1answer
1k views

Ethyl Acetate: how to store

I'm a 3D printing hobbyist and a few months ago I bought some Ethyl Acetate after learning online that it might have a similar effect on PLA as acetone has on ABS. From the tests I made, I was either ...
3
votes
1answer
193 views

Specific reduction of certain functional groups

Consider the compound $\ce{Alkyl-(4 oxocyclopent-2-ene)carboxylate (A)}$. For example consider- Now consider the operations: $\ce{1. (A) + (i)BH3/THF (ii) H+}$ $\ce{2. (A) + H2/Pt}$ ...
3
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0answers
650 views

Purification of polar NHS esters

What are the options that I might be missing for the purification of a molecule with the following characteristic: Contains an activated ester that reacts with water (NHS) Reacts readily with ...