Write a note on addition compounds of alcohol in aldehyde and ketone. $OR$ What are hemiacetal,acetal and ketal compounds? Give examples.
(N/A) Addition of alcohol to aldehyde compounds:
$(i)$ Hemiacetal: Aldehydes react with one equivalent of monohydric alcohol in the presence of dry hydrogen chloride to yield an alkoxyalcohol intermediate,known as a hemiacetal.
$(ii)$ Acetal: These further react with one more molecule of alcohol to give a gem-dialkoxy compound known as an acetal.
In a hemiacetal,the carbonyl carbon atom is attached to one alkoxy group and one hydroxyl group,whereas in an acetal,the carbonyl carbon atom is attached to two alkoxy groups.
$(b)$ Addition of alcohol to ketone compounds and ketal formation: Ketones react with dihydric alcohols like ethylene glycol under similar conditions to form cyclic products known as ethylene glycol ketals.
$(c)$ Dry hydrogen chloride protonates the oxygen of the carbonyl compounds,thereby increasing the electrophilicity of the carbonyl carbon and facilitating the nucleophilic attack of the alcohol.
$(d)$ Acetals and ketals are hydrolysed with aqueous mineral acids to yield the corresponding aldehydes and ketones,respectively.
$(i)$ Hemiacetal: Aldehydes react with one equivalent of monohydric alcohol in the presence of dry hydrogen chloride to yield an alkoxyalcohol intermediate,known as a hemiacetal.
$(ii)$ Acetal: These further react with one more molecule of alcohol to give a gem-dialkoxy compound known as an acetal.
In a hemiacetal,the carbonyl carbon atom is attached to one alkoxy group and one hydroxyl group,whereas in an acetal,the carbonyl carbon atom is attached to two alkoxy groups.
$(b)$ Addition of alcohol to ketone compounds and ketal formation: Ketones react with dihydric alcohols like ethylene glycol under similar conditions to form cyclic products known as ethylene glycol ketals.
$(c)$ Dry hydrogen chloride protonates the oxygen of the carbonyl compounds,thereby increasing the electrophilicity of the carbonyl carbon and facilitating the nucleophilic attack of the alcohol.
$(d)$ Acetals and ketals are hydrolysed with aqueous mineral acids to yield the corresponding aldehydes and ketones,respectively.
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Similar Questions
Compare the rate of reaction toward Beckmann rearrangement for the given oxime derivatives where $\gamma$ is: $(i) CH_3COO^-$,$(ii) ClCH_2COO^-$,$(iii) PhSO_3^-$.
Difficult
View SolutionIn the following table,Column-$I$ shows the structure of a compound,Column-$II$ shows its $IUPAC$ name,and Column-$III$ shows its common name. Match the $IUPAC$ name and common name for each structure given in Column-$I$.
| Column-$I$ (Structure) | Column-$II$ ($IUPAC$ name) | Column-$III$ (Common name) |
| :--- | :--- | :--- |
| $(A)$ $C_6H_4(CHO)_2$ (ortho) | $(i)$ Benzophenone | $(p)$ Acrolein |
| $(B)$ $(CH_3)_2C=CHCOCH_3$ | $(ii)$ Benzene$-1,2-$dicarbaldehyde | $(q)$ Diphenyl ketone |
| $(C)$ $CH_2=CH-CHO$ | $(iii)$ Prop$-2-$enal | $(r)$ Phthaldehyde |
| $(D)$ $(C_6H_5)_2CO$ | $(iv)$ $4-$methylpent$-3-$en$-2-$one | $(s)$ Mesityl oxide |
| Column-$I$ (Structure) | Column-$II$ ($IUPAC$ name) | Column-$III$ (Common name) |
| :--- | :--- | :--- |
| $(A)$ $C_6H_4(CHO)_2$ (ortho) | $(i)$ Benzophenone | $(p)$ Acrolein |
| $(B)$ $(CH_3)_2C=CHCOCH_3$ | $(ii)$ Benzene$-1,2-$dicarbaldehyde | $(q)$ Diphenyl ketone |
| $(C)$ $CH_2=CH-CHO$ | $(iii)$ Prop$-2-$enal | $(r)$ Phthaldehyde |
| $(D)$ $(C_6H_5)_2CO$ | $(iv)$ $4-$methylpent$-3-$en$-2-$one | $(s)$ Mesityl oxide |
Medium
View SolutionCompound $A$ $(C_9H_{10}O)$ shows a positive iodoform test. Oxidation of $A$ with $KMnO_4/KOH$ gives acid $B$ $(C_8H_6O_4)$. The anhydride of $B$ is used for the preparation of phenolphthalein. Compound $A$ is:
Given below are two statements: One is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$ : $Image-I$ can be easily reduced using $Zn-Hg / HCl$ to $Image-II$.
Reason $R : Zn-Hg / HCl$ is used to reduce carbonyl group to $-CH_2-$ group.
In the light of the above statements,choose the correct answer from the options given below:
Assertion $A$ : $Image-I$ can be easily reduced using $Zn-Hg / HCl$ to $Image-II$.
Reason $R : Zn-Hg / HCl$ is used to reduce carbonyl group to $-CH_2-$ group.
In the light of the above statements,choose the correct answer from the options given below:
DifficultJEE MAIN 2023
View SolutionArrange the following in increasing order of their reactivity for nucleophilic addition reaction:
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