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 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-...
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The Action of Nitrogen Iodide on Methyl Ketones

I recently encountered two old publications on action of nitrogen iodide on various compounds (Ref.1 and Ref.2). Between them, Ref.1 described the iodoform formation by methyl ketones upon treatment ...
Mathew Mahindaratne's user avatar
8 votes
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Do all α-hydroxy ketones give Tollens’ test?

It is well known that terminal α-hydroxy ketones give Tollens’ test, via tautomerisation. Also, α-hydroxy ketones flanked by aromatic groups give Tollens’ test, such as benzoin. But do all α-hydroxy ...
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Sulfonyl azides: diazo or azide transfer?

Sulfonyl azides, $\ce{RSO2N3}$, are capable of acting as sources of electrophilic azide ("$\ce{N+3}$"), but are also capable of effecting diazo transfer, as shown in the scheme below, taken from ref 1:...
orthocresol's user avatar
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How can I solve this synthesis?

I have this task to do: My solution: Is that possible? Can you please help me with the steps 2 and 3? This is what I did, but my teacher told me I should make the diketone (compound no. 5) from ...
Netta's user avatar
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Why are the unsaturated fatty acids usually unconjugated?

My textbook gives the structures of the unsaturated fatty acids in food including oleic acid, linoleic acid, linolenic acid and docosatetraenoic acid. I figure that when two or more $\ce{C=C}$ double ...
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Reactivity order of DIBAL-H and diborane with esters and acids

I have been taught in class that DIBAL-H is more reactive towards esters than carboxylic acids while opposite is true for diborane. Also DIBAL-H mentioned is taken under low temperatures (−78 °C). I ...
Satya's user avatar
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pKa of different sites of butanone

From what I can tell, deprotonation of the central hydrogen leads to the more thermodynamically stable product (most substituted double bond. i.e. most stabilization by hyperconjugation). Therefore, ...
Adroit's user avatar
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Stability of extended enolates

I'd expect an extended enolate to be more stable than a normal enolate, when both can form, but my textbook suggests otherwise. What is the stability of an extended enolate compared with a normal ...
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Why does the keto tautomer of guanine have lower energy?

Looking at the keto and enol forms of guanine, it would seem as if the enol form is more stable, due to the fact that aromaticity is established with the enol form. However, according to a question on ...
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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 ...
Jonathan Smith's user avatar
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Comparing acidic strength of phthalic acid isomers

I'd like to compare the acidic strengths of phthalic, isophthalic and terephthalic acids. As I understand, phthalic acid is the most acidic due to steric inhibition of resonance (SIR), but as ...
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Optical activity of tartaric acid

The meso-form of tartaric acid is optically inactive due to the plane of symmetry. But how are these forms able to show optical activity when the σ-bonds can freely rotate, which can change the ...
Nivedita Chowdhury's user avatar
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Does periodic acid cleave acetals?

Recently, I started reading about the cleavage reactions done by $\ce{HIO4}$. I came across a statement which read $\ce{HIO4}$ can't cleave acetals but it can cleave hemiacetals. But when I tried to ...
Chem-Learner's user avatar
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Can a per-acetylated sugar anomerize?

So I have a question concerning a reaction mechanism for the reaction below. I know for certain that I get the alfa anomer, but I can't explain it. When I draw out the mechanism it doesn't make sense ...
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Reaction of alpha hydroxyketone with KOH

What happens when 2-hydroxycyclohexan-1-one (an alpha hydroxyketone) reacts with aqueous $\ce{KOH}$? I tried something like Favorskii rearrangement, but it's wrong because OH isn't a good enough ...
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A Multistep Reaction Provided with IR Spectra (Guessing Started with Esterification)

Below, IR spectra for this sequence are provided: For compound E, I suggest the formation of a conjugated ester with the elimination of $\ce{-OH}$ group. The IR peak at $\pu{1732 cm-1}$ is a ...
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2-Iodoxybenzoic acid oxidation reaction

I was thinking about using 2-Iodoxybenzoic acid to selectively oxidize primary alcohols to aldehydes. I've found papers using various solvents like acetone/water mixture1, 2-methyl-2-propanol2, DMSO ...
steve d.'s user avatar
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Reagents for synthesis of ethyl 2-(2,3-dihydrobenzofuran-2-yl)acetate from naphthalen-1(4H)-one

The following conversion can be performed in a few steps. Show key intermediates and reagents (detailed mechanisms are not required). So I've been looking at this for a while and I can't seem ...
Simone Maarup Pedersen's user avatar
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An unconventional decarboxylation to form bullatenone

I recently had an assessment which required me to draw the mechanism of decarboxylation of a $\beta$-ketoacid. However, it is slightly peculiar because there is the presence of $\alpha$, $\beta$-...
Tan Yong Boon's user avatar
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Regioselectivity of the Beckmann rearrangement

It seems to be that the Beckmann rearrangement is a nice way to prepare secondary amines. This can be achieved by removal of oxygen via the use of $\ce{HI}$/$\ce{P}$. However, if ketones are used, ...
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Does alcohol hydrogen in the enol tautomer of a β-dicarbonyl have sp² character?

My reasoning for the somewhat implausible "$\mathrm{sp^2}$" character of the hydrogen between these two oxygens on the enol structure of the right comes from recognizing that if it were, then we would ...
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What is the average chain length of a glutaraldehyde crosslink between primary amines?

Imagine I'm performing a primary amine to primary amine (i.e. PA to PA) crosslinking reaction at $37~^{\circ}\mathrm{C}$ in phosphate-buffered saline (pH $\approx 7.4$) with glutaraldehyde drawn from ...
InsufficientlyModular's user avatar
4 votes
1 answer
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Mechanism for conversion of imide to ester with NaH

What is the mechanism of this reaction? My proposed mechanism is shown below, would it work?
Joe kent's user avatar
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Why are acid catalysed reactions of carbonyl compounds reversible?

I am currently studying aldehydes and ketones and their reactions. I've noticed that acid catalysed reactions are represented with reversible arrows, while base catalysed reactions are shown with ...
Hungry Blue Dev's user avatar
3 votes
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Why is a protonated carboxylic acid less acidic than a protonated ester?

To my understanding, both have analogous resonance structures except that the ester has on -OR and the carboxylic acid has an -OH. Why is a positive charge on C-O-R more stable than on C-O-H?
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What Is This Small Peak That Always Occurs Within Ketone Infra-Red Analysis?

After looking at a bunch of IR spectrums for ketones, I have noticed this tiny peak that I circled on the diagram below. Does anyone know what it actually is and if I can always use it to distinguish ...
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Use of boron(III) oxide for drying acetone

Acetone undergoes aldol self-condensation in the presence of acids or bases: which makes drying agents such as 3A/4A molecular sieves, barium oxide, potassium hydroxide and carbonate (basic), copper(...
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Are Wacker oxidations tolerant of carbonyl groups?

I was wondering if there was anything in the mechanism of a Wacker oxidation that would interfere with ketones or aldehydes already present in the molecule. Ketones and aldehydes can't be oxidized any ...
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Does the nucleophilic substitution in an acid chloride always proceed through a tetrahedral intermediate?

I am a beginner in organic chemistry and would like to ask for the mechanism for the nucleophilic substitution of carbonyl groups from acid chloride - especially regarding the tetrahedral intermediate?...
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Help with mechanism similar to Robinson Annulation

I need to figure out a mechanism for this reaction. All I know is that it is supposed to have a similar mechanism to Robinson Annulation. This is the best I could come up with, but I've been told it ...
dfalkjl3's user avatar
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Why aren't nitriles very good electrophiles?

I was wondering why nitriles do not react as electrophiles like carbonyl unless they have to, given that the C-N triple bond is still pretty polarized. The LUMO will be higher in energy than a ...
sweetandtangy's user avatar
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How does a cyclization occur with a carboxylic acid and (CF3CO)2O?

The product of the reaction below is unsaturated, bicyclic ketone, but I'm confused as to how (CF3CO)2O reacts with it to cause the cyclization. There is no base involved so I don't know how the ...
sweetandtangy's user avatar
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Will phosphorous Ylide participate in carbene generation and insertion?

The following question was sent to me . The answer for this question was given to me as option b I attempted it as following , recognizing the first step as a ylide reaction with a carbonyl compound....
Chakravarthy Kalyan's user avatar
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Claisen-like condensation with acid chloride

In the Claisen condensation, an ester enolate attacks an ester, with an alkoxide anion leaving subsequently to give a $\beta$-keto ester. Is it possible for a typical enolate of an aldehyde or ketone ...
Tan Yong Boon's user avatar
3 votes
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Why does the proton transfer from the oxygen to the nitrogen atom in imine formation not occur through an intramolecular process?

In my book Organic Chemistry by David Klein, 2nd edition, the book shows that the oxygen atom first takes a proton from an acid, then, the conjugate base of the acid takes a proton from the nitrogen ...
Teoc's user avatar
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What should be the correct sequence of reagents to be used in this reaction?

The correct sequence of reagents for the following conversion will be (1) $\ce{CH3MgBr, H+/CH3OH, [Ag(NH3)2]+OH-}$ (2) $\ce{CH3MgBr, [Ag(NH3)2]+OH-, H+/CH3OH}$ (3) $\ce{[Ag(NH3)2]+...
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Which enolate of butanone is more stable?

Consider butanone (A) and its two possible enolates B & C. Which of the two enolates will be more stable? B because of the more stable primary carbanion, or C because of more stable enolate (...
iBoy's user avatar
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Enol content of acetylacetone and ethyl acetoacetate

Why is the enol content of acetylacetone higher than that of acetoacetic ester? Hydrogen bonding stabilisation is present in enol form of both of them. I cannot figure out which factor makes one ...
user340743's user avatar
3 votes
0 answers
128 views

How can the ketone in a β-ketoester be protected during hydride reduction?

I am supposed to find what X is. I know that $\ce{LiAlH_4}$ will convert all carbonyl groups to alcohols, and the ester group is being reduced. The only way of ending up with a ketone that I can think ...
mathemather's user avatar
3 votes
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Why do electronegative heteroatoms increase C=O stretching frequency (bond strength)

Why does a more electronegative heteroatom (i.e. $\ce{Cl}$ or $\ce{O}$) increase the stretching frequency of a carbonyl? I'd suspect it's that they donate their lone pairs and we end up with a ...
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Nucleophillic addition vs SN2

The following question came in Paper 2 of JEE Advanced 2014- Here we have $\ce{CH3-}$ as the nucleophile. There are 2 possible attacks: SN2 type attack on the chlorine group. Nucleophilic addition ...
Akshat Joshi's user avatar
2 votes
0 answers
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Oxidation of 1,2 dicarbonyls by tollens reagent

According to the wiki page on Tollen's reagent https://en.wikipedia.org/wiki/Tollens%27_reagent#Qualitative_organic_analysis It also gives a positive test with hydrazines, hydrazones, α-hydroxy ...
mark's user avatar
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Comparing reactivity of benzaldehyde and 2-butanone for nucleophilic addition

I was taught that, in general, aldehydes are more reactive than ketones because of two reasons: 1) less steric hindrance, and 2) alkyl groups on both sides of carbonyl group in ketones have a stronger ...
AVS's user avatar
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2 votes
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Various pathways of an alpha diketone reaction

This is a question from JEE Advanced 1997. I have found two possible products of the reaction: By intramolecular aldol condensation: By benzil-benzilic acid type rearrangement: Which reaction takes ...
Lost Anisole's user avatar
2 votes
0 answers
170 views

IR Stretching in Hexacarbonyl Iron

With reference to this graph, my professor stated the following: "Since the IR band for the bridging carbonyls is single, it implies that the bridging carbonyls are oriented linearly. Since we ...
lazearoundallday's user avatar
2 votes
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When do the Wolff-Kishner Reduction and Clemmensen Reduction not take place for carbonyl compounds?

I came across some examples of organic compounds with acidic groups that didn't undergo the Clemmensen reduction. So, I was wondering which types of compounds the two reagents cannot reduce. Also, why?...
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Why aren't both alpha-carbons halogenated when acetone reacts with chlorine under UV?

My book shows the following reaction: Why is only one alpha carbon halogenated? I googled, but couldn’t find anything on it.
Tahsin Choudhury's user avatar
2 votes
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384 views

Does KCN prefer SN2 or nucleophilic addition?

If we have a 1° halide that also contains a carbonyl group (like 5‐chloropentan‐2‐one), and we add 1 mole of KCN in DMSO to it, what will happen? Will the SN2 product by substitution of chlorine or ...
Hridai Khurana's user avatar
2 votes
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Number of π electrons in all trans-2,4,6-octatrienoic acid

Sketch the Lewis structure of all trans-2,4,6-octatrienoic acid. (a) Consider the delocalized π electrons. Employ the particle-in-a-box model. Drawing on your knowledge about the occupation of ...
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