Step 1: Understanding the Concept:
Acidity is determined by the stability of the conjugate base formed after the loss of a proton.
Step 2: Detailed Explanation:
When an \(\alpha\)-hydrogen is removed from an aldehyde or ketone, a carbanion (enolate ion) is formed.
This carbanion is stabilized by resonance with the adjacent electron-withdrawing carbonyl group (\( >C=O \)).
The negative charge is delocalized onto the more electronegative oxygen atom.
Additionally, the strong electron-withdrawing \( -I \) effect of the carbonyl group weakens the \( C_\alpha - H \) bond.
Step 3: Final Answer:
The acidity is due to the resonance stabilization of the resulting enolate ion.
Write IUPAC names of the following compounds and classify them into primary, secondary and tertiary amines.
(i) (CH3 )2CHNH2 (ii) CH3 (CH2 )2NH2 (iii) CH3NHCH(CH3 )2
(iv) (CH3 )3CNH2 (v) C6H5NHCH3 (vi) (CH3CH2 )2NCH3 (vii) m–BrC6H4NH2
Give one chemical test to distinguish between the following pairs of compounds.
(i) Methylamine and dimethylamine
(ii) Secondary and tertiary amines
(iii) Ethylamine and aniline
(iv) Aniline and benzylamine
(v) Aniline and N-methylaniline
Account for the following:
(i) pKb of aniline is more than that of methylamine.
(ii) Ethylamine is soluble in water whereas aniline is not.
(iii) Methylamine in water reacts with ferric chloride to precipitate hydrated ferric oxide.
(iv) Although amino group is o– and p– directing in aromatic electrophilic substitution reactions, aniline on nitration gives a substantial amount of m-nitroaniline.
(v) Aniline does not undergo Friedel-Crafts reaction.
(vi) Diazonium salts of aromatic amines are more stable than those of aliphatic amines. (vii) Gabriel phthalimide synthesis is preferred for synthesising primary amines.
What is meant by the following terms? Give an example of the reaction in each case.
\((i)\)\(Cyanohydrin\)
\((ii)Acetal \)
\((iii)Semicarbazone \)
\((iv)Aldol \)
\((v)Hemiacetal \)
\((vi)Oxime \)
\((vii)Ketal \)
\((vii)Imine \)
\((ix)\)\(2,4-DNP-derivative \)
\((x)Schiff's base\)
Name the following compounds according to IUPAC system of nomenclature:
\((i) CH_3CH(CH_3)CH_2CH_2CHO \)
\((ii) CH_3CH_2COCH(C_2H_5)CH_2CH_2Cl \)
\((iii) CH_3CH=CHCHO \)
\((iv) CH_3COCH_2COCH_3 \)
\((v) CH_3CH(CH_3)CH_2C(CH_3)_2COCH_3 \)
\((vi) (CH_3)_3CCH_2COOH \)
\((vii) OHCC_6H_4CHO-p\)
Write the IUPAC names of the following ketones and aldehydes. Wherever possible, give also common names.
\((i) CH_3CO(CH_2)_4CH_3 \)
\((ii) CH_3CH_2CHBrCH_2CH(CH_3)CHO \)
\((iii) CH_3(CH_2)_5CHO \)
\((iv) Ph-CH=CH-CHO\)
\((v)\)
\((vi) PhCOPh\)
Draw structures of the following derivatives.
(i)The 2,4-dinitrophenylhydrazone of benzaldehyde
(ii)Cyclopropanone oxime
(iii)Acetaldehydedimethylacetal
(iv)The semicarbazone of cyclobutanone
(v)The ethylene ketal of hexan-3-one
(vi)The methyl hemiacetal of formaldehyde
Predict the products formed when cyclohexanecarbaldehyde reacts with following reagents.
(i)\(PhMgBr\) and then \(H3O + \)
(ii)Tollens' reagent
(iii) Semicarbazide and weak acid
(iv)Excess ethanol and acid
(v) Zinc amalgam and dilute hydrochloric acid