19,000+ solved questions for JEE Advanced, JEE Mains, NEET & IChO — with answers and expert explanations.
Assertion: Chloral reacts with phenyl chloride to form DDT. Reason: It is an electrophilic substitution reaction
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: 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: 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: Ph–CO–CH2CH2OCH3 has greater reactivity for E1CB than for E2 reaction. Reason: A poor leaving group and acidic —H favour E1CB mechanism.
The order of reactivities of the following alkyl halides for a SN2 reaction is
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.
Assertion: Chlorination of allylic hydrogen is difficult than vinylic hydrogen. Reason: Allyl radical is stabilised by resonance.
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: Allyl halide (CH2=CH–CH2X) is more reactive than CH3CH2CH2X in a SN2 reaction. Reason: Allyl halide forms a resonance stabilized carbocation
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: Rate of reaction is dependent only on the concentration of nucleophile in SN1 reactions. Reason: Polar solvent favors SN1 reaction.
Assertion: Heavy metal ions Ag + or Pb 2+ decrease SN1 reactivity. Reason : They aid ionisation of RX.
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: Benzyl bromide when kept in acetone – water, produces benzyl alcohol. Reason: The reaction follows SN2 mechanism.
Assertion: Consider the following synthesis CH3ONa + PhBr Path–II yields better yield of product than Path-I. Reason: CH3ONa is stronger base than PhONa.
Which of the following bases would give the best yield for the substitution product when reacted with 2-chloropropane?
For the following reactions, (i) CH CH CH Br KOH CH CH CH KBr H O -> (ii) (iii) Which of the following statements is correct? (NEET 2016)
Consider the reaction, CH CH CH Br NaCN CH CH CH CN NaBr -> This reaction will be the fastest in (NEET 2016)
The reaction of C6H5CH=CHCH3 with HBr produces (AIPMT 2015)
This reaction would follow which of the following pathway predominantly?
Which one of the following will give racemised product in C2H5OH? (a) (b) (c) (d)
The decreasing order of nucleophilicity among the nucleophiles
Which of the following species is a nucleophile?
Which of the following species is a nucleophile?