19,000+ solved questions for JEE Advanced, JEE Mains, NEET & IChO — with answers and expert explanations.
Assertion: Benzyl bromide when kept in acetone – water, produces benzyl alcohol. Reason: The reaction follows SN2 mechanism.
Assertion: In SN1 mechanism, the product with inversion of configuration is obtained in a higher amount compared to the product with the retention of configuration. Reason: Front side attack of nucleophile is hindered…
Assertion: Heavy metal ions Ag + or Pb 2+ decrease SN1 reactivity. Reason : They aid ionisation of RX.
Assertion: Rate of reaction is dependent only on the concentration of nucleophile in SN1 reactions. Reason: Polar solvent favors SN1 reaction.
Assertion: Consider the following SN2 reactions. (I) and (II) Reaction (II) occurs at a faster rate than (I) Reason: Anion of reaction (II) is a stronger base than the anion of reaction (I).
Assertion: Allyl halide (CH2=CH–CH2X) is more reactive than CH3CH2CH2X in a SN2 reaction. Reason: Allyl halide forms a resonance stabilized carbocation
Assertion: SN2 reaction of CH3––Br is faster in Cl CH S – SCH3 Cl (CH ) CHS 3 2 – SCH(CH ) 3 2 DMSO than in H2O. Reason: DMSO has greater capability to solvate nucleophile.
Assertion: Chlorination of allylic hydrogen is difficult than vinylic hydrogen. Reason: Allyl radical is stabilised by resonance.
Assertion: Treatment of either enantiomer of 2-chlorobutane with ethanolic KOH results in trans-2- butene as major elimination product. Reason: Elimination with ethanolic KOH is a bimolecular reaction.
The rate of SN1 reaction is fastest with: (a) (b) (c) CH Br CH NO2 Br (d)
Assertion: Ph–CO–CH2CH2OCH3 has greater reactivity for E1CB than for E2 reaction. Reason: A poor leaving group and acidic —H favour E1CB mechanism.
Assertion: The reaction of bulky base such as potassium tertiary butoxide [(CH3)3CO–K+] with secondary alkyl halides gives predominantly E2 elimination product rather than SN2 substitution product. Reason: The transit…
Assertion: p-nitrochlorobenzene is more reactive than m-nitrochlorobenzene towards aromatic nucleophilic substitution reaction. Reason: Nitro group from para and meta positions has opposite effect in aromatic nucleoph…
Assertion: A dichlorobenzene is slightly more reactive than chlorobenzene towards an aromatic nucleophilic substitution reaction. Reason: Chlorine has electron withdrawing effect on aromatic ring.
Assertion: Chloral reacts with phenyl chloride to form DDT. Reason: It is an electrophilic substitution reaction
The major product obtained when this alkyl halide is subjected to E2 – reaction will be (a) (b) (c) (d)All three products in equal proportions
Which of the following species is an electrophile?
Which of the following species is an electrophile?
Which of the following species is a nucleophile?
Which of the following species is a nucleophile? (a) CH O
Which of the following species is a nucleophile?
Which of the following species is a nucleophile?
The decreasing order of nucleophilicity among the nucleophiles
Consider the following groups (I) — OCOCH3 (II) — OCH3 (III) — OSO2CH3 (IV) — OSO2CF3 The decreasing order of their leaving ability is
Among these nucleophiles, which of the following orders is correct for their nucleophilicity order in gas phase? - CH , NH , OH ,F (a) - CH >NH >OH >F (b) F OH NH CH (c) - OH >NH >F >CH