Pinacol-pinacolone and related rearrangements

36 questions on Pinacol-pinacolone and related rearrangements from the Alcohols, Phenols and Ethers chapter: 6 NEET level, 16 JEE Main, 14 JEE Advanced. Each one opens with its answer and solution.

• Pinacol, the starting diol of the pinacol-pinacolone rearrangement, has the IUPAC name NEET level
• On heating with dilute H2SO4, pinacol gives pinacolone, which is NEET level
• The key reactive intermediate in the acid-catalysed pinacol rearrangement is a NEET level
• 2,3-Diphenylbutane-2,3-diol is treated with dilute H2SO4 and warmed. The main product is (use the convention that phenyl migrates in preference to methyl) JEE Main level
• 1,1-Diphenylethane-1,2-diol, (C6H5)2C(OH)-CH2OH, is warmed with dilute H2SO4. The product is JEE Main level
• Treatment of 1-(aminomethyl)cyclohexan-1-ol with NaNO2/dilute HCl at 273 K gives mainly JEE Main level
• According to the usual JEE-level order of migratory aptitude in pinacol-type rearrangements (aryl bearing an electron-donating group > phenyl > alkyl, larger al... JEE Main level
• 2-Methylpropane-1,2-diol, (CH3)2C(OH)-CH2OH, is heated with dilute H2SO4. The product is JEE Main level
• 3,3-Dimethylbutan-2-ol is heated with conc. H2SO4. The major alkene formed is JEE Main level
• Which of the following statements about the pinacol rearrangement are correct? JEE Main level
• 2-Methyl-3-phenylbutane-2,3-diol, (CH3)2C(OH)-C(OH)(CH3)(C6H5), is heated with dilute H2SO4. The product is JEE Main level
• The diol formed by joining C-1 of one cyclopentane ring to C-1 of another cyclopentane ring, each of these two carbons also carrying one OH group (1,1'-bi(cyclo... JEE Advanced level
• 2-Amino-1,1-diphenylethan-1-ol, (C6H5)2C(OH)-CH2NH2, is treated with NaNO2/HCl at 273 K. The main organic product is JEE Advanced level
• Which of the following diols give a ketone (and not an aldehyde) as the major product on treatment with dilute H2SO4 and heat? JEE Advanced level
• The diol (C6H5)2C(OH)-C(OH)(CH3)(CH2CH3) (1,1-diphenyl-2-methylbutane-1,2-diol) is heated with dilute acid. Take the migratory aptitude as phenyl > ethyl > meth... JEE Advanced level
• 1-(4-Methoxyphenyl)-2-methyl-1-phenylpropane-1,2-diol, (4-CH3O-C6H4)(C6H5)C(OH)-C(OH)(CH3)2, is treated with dilute H2SO4. The main product is JEE Advanced level
• Which of the following combinations give cycloheptanone as the main product? JEE Advanced level
• 3,4-Dimethylhexane-3,4-diol, CH3CH2-C(OH)(CH3)-C(OH)(CH3)-CH2CH3, is heated with dilute acid. Assuming ethyl migrates in preference to methyl, the main product ... JEE Main level
• On heating with dilute acid, pinacol (2,3-dimethylbutane-2,3-diol) undergoes the pinacol-pinacolone rearrangement to give NEET level
• Which reagent system converts propanone into pinacol (2,3-dimethylbutane-2,3-diol) by bimolecular reduction? NEET level
• The key reactive intermediate in the acid-catalysed pinacol-pinacolone rearrangement is a NEET level
• 2-Methylpropane-1,2-diol, (CH3)2C(OH)-CH2OH, is warmed with dilute H2SO4 and rearranges. The carbonyl product is JEE Main level
• 1,1-Diphenylethane-1,2-diol, (C6H5)2C(OH)-CH2OH, is treated with dilute H2SO4. The rearranged product is JEE Main level
• 1,1'-Bi(cyclohexyl)-1,1'-diol (two cyclohexane rings joined by a bond between the two carbons that each carry an OH group) is treated with acid. The rearrangeme... JEE Main level
• 1-(Aminomethyl)cyclohexan-1-ol is treated with NaNO2/dilute HCl at 273 K (Tiffeneau-Demjanov type ring expansion). The major carbonyl product is JEE Main level
• Neopentyl alcohol (2,2-dimethylpropan-1-ol) is heated with conc. H2SO4. The major alkene formed is JEE Main level
• 3-Methylbutan-2-ol is shaken with conc. aqueous HBr (SN1 conditions). The major alkyl bromide is JEE Main level
• Which statements about pinacol, (CH3)2C(OH)-C(OH)(CH3)2, are correct? JEE Main level
• Benzophenone is irradiated in propan-2-ol to give X, C26H22O2. X is treated with a trace of iodine in glacial ethanoic acid (acid-catalysed rearrangement) to gi... JEE Advanced level
• 1-Methylcyclohexane-1,2-diol is warmed with dilute H2SO4. Assume the tertiary carbocation forms first and that hydride migration is the preferred shift. The maj... JEE Advanced level
• 3,3-Dimethylbutan-2-ol, (CH3)3C-CH(OH)-CH3, is heated with conc. H2SO4. The major alkene is JEE Advanced level
• A compound X, C6H14O2, is cleaved by HIO4 to give only propanone (2 mol per mol of X). Heating X with dilute H2SO4 gives Y, C6H12O, which gives a yellow precipi... JEE Advanced level
• 2,3-Diphenylbutane-2,3-diol, CH3-C(OH)(C6H5)-C(OH)(C6H5)-CH3, is treated with dilute acid. Which statements are correct? JEE Advanced level
• 1-(Aminomethyl)cyclopentan-1-ol is treated with NaNO2/dilute HCl at 273 K. Which statements are correct? JEE Advanced level
• 2,2-Dimethyloxirane (isobutylene oxide) is treated with a catalytic amount of BF3 in dry ether. The product is JEE Advanced level
• Cyclopentanone is treated with Mg-Hg and water to give X. X is warmed with dilute H2SO4 to give Y, which is reduced with NaBH4 (then H3O+) to give Z. Z is JEE Advanced level