Questions tagged [carbonyl-compounds]

For questions about compounds containing the carbonyl group, C=O, the carboxylic acid group (-COOH), or its derivatives (anhydrides/esters/amides/acid halides). For questions about complexes involving carbon monoxide as a ligand use [carbonyl-complexes] instead.

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Why is acetic acid more acidic than phenol?

Acetic acid (ethanoic acid, $\mathrm pK_\mathrm a \approx 5$) is more acidic than phenol ($\mathrm pK_\mathrm a \approx 10$), which is reflected in their reactivity with a weak base such as sodium ...
Manisha Poudel's user avatar
22 votes
1 answer
19k views

Migratory aptitude in Baeyer-Villiger reaction

In short, I do not understand how or why the migratory aptitude is as listed in every textbook I've read. Firstly, they talk about a positive charge being built up that is stabilised by the movement ...
Ari Ben Canaan's user avatar
28 votes
3 answers
59k views

Rationalising the order of reactivity of carbonyl compounds towards nucleophiles

This is immediately following ron's answer from Why is a ketone more nucleophilic than an ester? One of the most simplest questions you can ask, how can you rationalise the order of reactivity ...
Martin - マーチン's user avatar
42 votes
1 answer
6k views

In what way could benzoin give Tollen's test?

In Q29 of Joint Entrance Exam (JEE) 2016 India, the official answer key mentions that benzoin gives Tollen's test. However, I saw this post which says that it doesn't: Why do α-hydroxy ketones give ...
Jeevesh Juneja's user avatar
29 votes
2 answers
15k views

Does a Grignard reagent react with enones to give the 1,2- or 1,4- product?

Cyclohexenone, an α,β-unsaturated ketone, is electrophilic at both the carbonyl carbon, as well as the β-carbon. So, it can either undergo 1,2-addition to give the allylic alcohol 1, or 1,4-addition ...
miyagi_do's user avatar
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0 votes
1 answer
2k views

Why does a hydride shift take place in the cannizzaro reaction?

Hydride is a poor leaving group so a hydride shift should not take place and instead the attacking hydroxyl should leave the carbonyl group. I don’t understand why this doesn’t happen?
Sahil Gupta's user avatar
22 votes
4 answers
8k views

Why do Organolithium or Grignard reagents act as nucleophiles and not as bases with aldehydes and ketones

I've read entire Chapter 14: Organometallic Compounds of Francis Carey's "Organic Chemistry" but I still didn't get an answer to my question. Quote from the book: Because of their basicity ...
claws's user avatar
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17 votes
2 answers
14k views

Is tropone aromatic?

Looking at resonance structure 1a, it doesn't seem that tropone is aromatic. However, the resonance structure 1b with $\ce{C+-O-}$ satisfies Hückel's rule for aromaticity. Is it correct to say that ...
EJC's user avatar
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5 votes
1 answer
11k views

Mechanism for oxidation of primary alcohols to carboxylic acids

My teacher told me that the following is the mechanism for oxidation of primary alcohols to carboxylic acids: I've searched in books and online and didn't find a similar mechanism. For example, in ...
Vinicius ACP's user avatar
28 votes
3 answers
11k views

Which compound reacts faster in the Cannizzaro Reaction?

Which reacts faster in the Cannizzaro Reaction? a) $\ce{OHC-C6H4-NO2}$ b) $\ce{OHC-C6H4-OCH3}$ Obviously, a better hydride releasing group will react faster. Therefore my answer was b, as $\ce{-...
Shubham's user avatar
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24 votes
2 answers
10k views

Comparing acidities of substituted and aromatic carboxylic acids

When comparing the acidities of carboxylic acids, we primarily see the electropositivity of the carboxylic acid carbons, i.e. we see how effectively the negative charge on the carboxylate ion is ...
stochastic13's user avatar
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17 votes
1 answer
22k views

Does acetic acid give a positive result with the iodoform test?

Acetic acid contains a $\ce{-COMe}$ group, so theoretically, it should give a positive result in the iodoform test (i.e. a yellow precipitate of $\ce{CHI3}$ being formed). But apparently the iodoform ...
rishab bairagi's user avatar
12 votes
3 answers
64k views

Mechanism for reaction of Tollens' reagent with aldehydes

Upon treatment with Tollens' reagent (ammoniacal silver(I) nitrate), aldehydes are oxidised to carboxylic acid, and silver(I) is reduced to silver metal. I am trying to find a mechanism for the this ...
Pepria's user avatar
  • 567
12 votes
2 answers
4k views

Regioselective enolate formation

Our professor only told us that A is favored, and B is not getting formed. I thought about the resonance structures and saw a contradiction to that what the prof told us. To be honest I think my ...
laminin's user avatar
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12 votes
1 answer
7k views

Why do alpha-hydroxy ketones respond positively to Tollens', Fehling's, Benedict's, Schiff's and HgCl2 tests?

I learnt from a certain textbook that aldehydes and formic acid respond positively to Tollens', Fehling's, Benedict's, Schiff's and HgCl2 tests. However, in another textbook I read that even alpha-...
user avatar
7 votes
1 answer
15k views

Preparation of oxalic acid from acetylene

I think that using ozonolysis would be a good idea to prepare oxalic acid from acetylene. Upon ozonolysis of acetylene we would get glyoxal: $$\ce{O=CH-HC=O}$$ Would I obtain the oxalic acid upon ...
Gummy bears's user avatar
6 votes
2 answers
5k views

In Reimer-Tiemann reaction why does phenol attack the carbene from ortho position?

From the Wikipedia article on Reimer-Tiemann reation: In step 5, why doesn't the oxygen attack the carbene. The way I see it: upon attacking the carbene from ortho position, the mechanism ...
Avyansh Katiyar's user avatar
26 votes
2 answers
51k views

Why does benzaldehyde not respond to Fehling's test?

All aldehydes are supposed to respond to Fehling's test. So why doesn't benzaldehyde respond to it? Does it have something to do with the fact that benzaldehyde is an aromatic compound? If so, then ...
user avatar
25 votes
1 answer
2k views

How can I determine if there are π-π interactions between an amide and an aromatic ring in a protein?

In a crystal structure I've determined, a triazole ring on my ligand appears to be stacking with a tyrosine (top in picture): However, there is also an amide, courtesy a glutamine, near it (bottom). ...
Nick T's user avatar
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20 votes
1 answer
29k views

Reduction of carboxylic acids by LiAlH4

I've read that when a carboxylic acid reacts with $\ce{LiAlH4}$ the corresponding alcohol is formed: But when I try to think of the mechanism, I get stuck here: $\ce{LiAlH4}$ produces $\ce{H-}$. ...
Quark's user avatar
  • 411
16 votes
1 answer
12k views

Can an amide nitrogen be a hydrogen bond acceptor?

Can $\ce{N}$ (i.e. main chain $\ce{NH}$s of recognised residues in a peptide or protein) be a hydrogen bond acceptor? It is a well known fact that the main chain $\ce{NH}$s can be a hydrogen bond ...
mkHun's user avatar
  • 213
16 votes
1 answer
21k views

Which factors determine the keto:enol ratio for aldehydes, ketones, and 1,3-dicarbonyl compounds?

Arrange the following compounds in order of increasing enol content: I think the order is D > C > B > A considering conjugation, hyperconjugation and hydrogen bonding. The enol formed in ...
Aditya Dev's user avatar
  • 7,706
15 votes
5 answers
7k views

Why can enolizable aldehydes undergo Cannizzaro reactions?

Why does 2-methylpropanal undergo a Cannizzaro reaction even though it has an $\alpha$-hydrogen?
Utkarsh Gupta's user avatar
13 votes
2 answers
3k views

How is the Felkin-Anh model of stereoinduction correctly explained with MO theory?

One method to predict stereoinduction in asymmetric reactions is the Felkin-Anh model (derived from the more basic Cram model) that applies to nucleophile attacks on α-chiral aldehydes. In a ...
Jan's user avatar
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11 votes
1 answer
4k views

Why are beta-ketoacids better at decarboxylation than gamma or delta?

My book claims that beta-ketoacids and beta-dicarboxylic acids are better at decarboxylating than their gamma and delta counterparts. Why is that? I would assume that since gamma and delta keto-acids ...
Nova's user avatar
  • 1,732
10 votes
2 answers
5k views

Carbonyl oxygen as nucleophile

Aldehydes and ketones have electrophilic centres at their carbonyl C, since the carbonyl O polarises the bond and attracts electron density towards itself on account of its high electronegativity. But ...
Charles's user avatar
  • 2,715
9 votes
4 answers
2k views

Do enolates get protonated at the carbon or oxygen atom?

An enolate has two resonance structures. When it gets protonated, where is the $\ce{H+}$ more likely to go? On the oxygen to produce an enol, which tautomerizes to the keto, or on directly onto the ...
hanna's user avatar
  • 647
8 votes
1 answer
18k views

IUPAC name for citric acid

I wonder what the name is of the following structure is: I think it's something like 3-hyrodxypentanoic diacid However, I wasn't able to find how to name a side chain if it contains a $\ce{COOH}$ ...
KingBoomie's user avatar
7 votes
2 answers
6k views

Cannizarro reaction of chloral

When chloral undergoes reaction with a concentrated alkali, will it undergo Cannizarro reaction to form the corresponding alcohol and acidic salt, or should it form chloroform instead by departure of ...
Saurabh Raje's user avatar
6 votes
1 answer
2k views

Can the hydroxyl group of 4-hydroxybenzoic acid react with phosphorus pentachloride?

I learned that, a phenol will not react (or react very slowly) with $\ce{PCl5}$ due to its stabilized structure. How about the $\ce{-OH}$ group on the benzene ring of 4-hydroxybenzoic acid? Will that ...
txn's user avatar
  • 101
6 votes
1 answer
4k views

How can this ketone show Cannizzaro reaction?

According to answer key, Cannizzaro reaction of 3-hydroxy-2,2-dimethyl-1-phenylpropan-1-one (a ketone) takes place but how is that possible when we know only aldehydes show Cannizzaro reaction?
user167110's user avatar
5 votes
2 answers
3k views

Étard Reaction of Ethylbenzene

What is the major product when the following compound undergoes Étard reaction? Is it acetophenone or a terminal aldehyde. The mechanism discussed in Mechanism for an Étard reaction (chromium complex)...
ishwar b b's user avatar
5 votes
1 answer
1k views

Epoxide ring opening via decarboxylation

The answer for the above multiple choice problem is option (C), from which I can understand that at some point in the mechanism the molecule must've undergone decarboxylation. Also, I think the first ...
stoic-santiago's user avatar
21 votes
1 answer
2k views

Can we use phosphorus triiodide in Hell-Volhard-Zelinsky reaction?

Using the Hell–Volhard—Zelinksy (HVZ) reaction, we can get alpha-chloro or alpha-bromo carboxylic acids: Is it possible to similarly make alpha-iodo carboxylic acids with the help of HVZ reaction? I ...
Nilay Ghosh's user avatar
  • 25.3k
19 votes
1 answer
10k views

Are groups other than carbonyl reduced by Clemmensen reduction?

According to my textbook, Clemmensen reduction reduces only aldehydes and ketones to alkanes. But in this question: $\ce{Zn-Hg/HCl}$ has reduced both the ketonic and nitro group. Correct answer given ...
Akash Goel's user avatar
19 votes
1 answer
4k views

How can benzaldehyde have a pKa of 14.9?

There are numerous websites out there which claim that the pKa of benzaldehyde – C6H5CHO – is 14.90. (Just do a Google search for benzaldehyde pka to see what I ...
orthocresol's user avatar
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19 votes
1 answer
25k views

Does Br2/H2O oxidize all aldehydes including carbohydrates?

In many books, it is mentioned that aldehydes are easily oxidized even by mild oxidizing agents. However, I have never seen bromine water explicitly mentioned. But in the carbohydrates chapter, it is ...
Kartik's user avatar
  • 841
17 votes
1 answer
57k views

What is the mechanism for oxidation of ketones by the Popoff's rule?

Ketones are relatively much harder to oxidise, but they do undergo oxidation reactions at extreme temperatures. Our teacher also told us about Popoff's rule which states that, on oxidation of ...
nilanjana's user avatar
  • 863
15 votes
1 answer
25k views

Mechanism of carboxylic acid and amide dehydration with phosphorus pentoxide

Dehydration of carboxylic acids with phosphorus pentoxide ($\ce{P2O5}$) yields acid anhydrides, and in a similar reaction, amides dehydrated with phosphorus pentoxide yield cyanides. Can an arrow ...
Charles's user avatar
  • 2,715
13 votes
2 answers
6k views

Why is benzoic acid a stronger acid than 3-aminobenzoic acid?

Why is benzoic acid a stronger acid than 3-aminobenzoic acid? Obviously at meta position, only negative inductive effect will operate. But, how does that make it a weaker acid than benzoic acid?
Prajwal Chauhan's user avatar
13 votes
1 answer
1k views

What is the most acidic proton of 2-methylcyclopent-2-en-1-one?

In an acid-base reaction of $\ce{HO-}$ with 2-methylcyclopent-2-en-1-one, which is the most acidic proton? I had assumed it was one of them coming off C-5 according to IUPAC numbering (the sp3 carbon ...
vitno's user avatar
  • 133
12 votes
1 answer
6k views

Will the bond order of CO be greater in its existence as carbon monoxide or in metal carbonyl?

$$\text{Bond order} = \frac{N(b) - N(a)}{2}$$ Where $N(b)$ is the number of electrons in bonding orbitals and $N(a)$ is the number of electrons in antibonding orbitals. As in metal carbonyls, there is ...
Resorcinol's user avatar
  • 1,439
11 votes
1 answer
28k views

Is an ester or a ketone more acidic?

Two organic chemistry textbooks I've read (by Bruice and by Tandon) say: Esters are more acidic than ketones, because the resonance between the two oxygen atoms gives less opportunity for the ...
Amogh's user avatar
  • 155
11 votes
1 answer
6k views

IUPAC naming for compounds containing carboxylic acid and anhydride together?

According to IUPAC, the carboxylic acid comes first in priority order for functional groups, while anhydride has no prefix. Then how do you name a compound which contains both a carboxylic acid and an ...
user282856's user avatar
11 votes
1 answer
6k views

Mechanism for conversion of ketone to dichloride with phosphorus pentachloride

I would like to know the mechanism of this reaction leading to the formation of a geminal dichloride. I am unable to predict how the $\ce{C=O}$ breaks and how the 2 $\ce{Cl}$ atoms replace the oxygen ...
Archer's user avatar
  • 5,433
8 votes
2 answers
3k views

How can an aromatic ketone be reduced in the presence of a nitro group?

Is it possible to reduce an acyl group to an alkane, but still keep a nitro group intact without its reduction to an amino group? A Clemmensen reduction would reduce the nitro group, and it seems like ...
user avatar
8 votes
3 answers
20k views

Does DIBAL-H reduce carboxylic acids?

Diisobutylaluminium hydride(DIBAL-H) reduces only carboxylic acid, ester or both? The answer given was that it only reduces ester. Is it correct that under any condition carboxylic acids are not ...
sonu's user avatar
  • 268
8 votes
3 answers
2k views

Which tautomer of hexane-2,4-dione is more stable?

Which tautomer will be more stable? Both 1 and 2 show intramolecular hydrogen bonding and form 6 membered cyclic ring, thus increasing the stability. I think I need to compare the effect of the two ...
Prakhar's user avatar
  • 2,351
7 votes
2 answers
10k 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 ...
Dissenter's user avatar
  • 18.8k
5 votes
1 answer
2k views

Nucleophilic attack at a carbonyl - angle of attack

What is the specific angle between the carbonyl carbon and the nucleophile during the nucleophilic addition reaction?
yayati naresh's user avatar