Practice free Hydrocarbons (Chemistry) NEET multiple-choice questions online with instant answers and detailed explanations. No login required.
Identify the correct reagents that would bring about the following transformation.
Ph–CH₂–CH=CH₂ → Ph–CH₂–CH₂–CHO
Anti-Markovnikov OH placement needs hydroboration-oxidation, then PCC oxidises the primary alcohol selectively to the aldehyde (CrO₃ would over-oxidise to the carboxylic acid).
A compound with a molecular formula of $C_6H_{14}$ has two tertiary carbons. Its IUPAC name is:
$(CH_3)_2CH\text{-}CH(CH_3)_2$ has two adjacent tertiary carbons.
For the given reaction: Ph–CH=CH–Ph $\xrightarrow{KMnO_4/H^+}$ 'P' (major product). 'P' is:
Hot acidic KMnO₄ cleaves the C=C oxidatively; each side becomes a –COOH on the phenyl ring → benzoic acid.
Predict the major product "P" in the following sequence of reactions: 1-methylcyclopentene $\xrightarrow{\text{(i) HBr, benzoyl peroxide}}\xrightarrow{\text{(ii) KCN}}\xrightarrow{\text{(iii) Na(Hg)/C}_2\text{H}_5\text{OH}}$ P (Major)
(i) HBr with peroxide adds Br anti-Markovnikov to the less-substituted carbon (C2). (ii) KCN does SN2 → nitrile at C2. (iii) Na(Hg)/EtOH reduces –CN to –CH₂NH₂. Product: CH₃ and –CH₂NH₂ on adjacent ring carbons.
Which one of the following reactions does NOT give benzene as the product?
Benzene diazonium chloride with warm water gives phenol (and N₂), not benzene. The other three (decarboxylation, aromatization of hexane, cyclic trimerization of ethyne) all give benzene.
How many products (including stereoisomers) are expected from monochlorination of the following compound: $(\text{CH}_3)_2\text{CH–CH}_2\text{–CH}_3$ (2-methylbutane)?
Four constitutional monochloro products; two of them (1-chloro-2-methylbutane and 2-chloro-3-methylbutane) contain a stereocentre giving a pair of enantiomers each. Total $= 2+1+2+1 = 6$.
Which one of the following compounds does NOT decolourize bromine water?
Cyclohexane is a saturated hydrocarbon and does not react with bromine water. Phenol and aniline brominate the ring; styrene adds across the C=C.
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