Dehydration of alcohols and dehydrohalogenation

39 questions on Dehydration of alcohols and dehydrohalogenation from the Organic Reaction Mechanisms IV: Elimination chapter: 8 NEET level, 16 JEE Main, 15 JEE Advanced. Each one opens with its answer and solution.

• When ethanol is heated with excess conc. H2SO4 at 443 K, the main product is NEET level
• The correct order of ease of acid-catalysed dehydration of alcohols is NEET level
• Butan-2-ol is heated with conc. H2SO4 at 440 K. The major product is NEET level
• 1,2-Dibromoethane on heating with excess NaNH2 (followed by water) gives mainly NEET level
• 3-Methylbutan-2-ol is heated with conc. H2SO4. The major alkene is JEE Main level
• Ethanol is heated with conc. H2SO4 at 413 K with excess alcohol, forming ethoxyethane. The carbon-oxygen bond of the ether is formed by JEE Main level
• Neopentyl alcohol, (CH3)3C-CH2OH, is heated with conc. H2SO4. The major alkene is JEE Main level
• 3,3-Dimethylbutan-2-ol is treated with POCl3 in pyridine. The principal product is JEE Main level
• 1,2-Dibromopropane is heated with excess NaNH2, and the mixture is then treated with water. The final product is JEE Main level
• The relative reactivity of the ethyl halides C2H5X toward E2 elimination by NaOEt is JEE Main level
• In which of the following pairs do the two alcohols give the same major alkene on dehydration with conc. H2SO4 at about 440 K? JEE Main level
• Which of the following statements about the E1 mechanism of dehydrohalogenation are correct? JEE Main level
• cis- and trans-1-Bromo-2-methylcyclohexane are treated with NaOEt/ethanol (E2, requiring an axial bromine and an anti axial beta hydrogen). Which is correct? JEE Advanced level
• The ring of tert-butylchlorocyclohexane is locked with the tert-butyl group equatorial. With (CH3)3COK in (CH3)3COH at 298 K, the second-order E2 rate constants... JEE Advanced level
• (1-Methylcyclobutyl)methanol, (CH2)3C(CH3)-CH2OH (a cyclobutane ring bearing a methyl and a hydroxymethyl on the same carbon), is heated with conc. H2SO4. The m... JEE Advanced level
• meso-1,2-Dibromo-1,2-diphenylethane and its racemic diastereomer (1R,2R / 1S,2S) are each treated with one equivalent of NaOEt (anti E2 giving 1-bromo-1,2-diphe... JEE Advanced level
• (E)-But-2-ene and (Z)-but-2-ene are each treated with Br2 (anti addition), and each dibromide is then treated with one equivalent of strong base for an anti E2 ... JEE Advanced level
• 3,3-Dimethylbutan-2-ol is heated with conc. H2SO4. Select all correct statements. JEE Advanced level
• Which of the following bromides give only ONE constitutional isomer of an alkene on E2 elimination (no rearrangement, E/Z isomers ignored)? JEE Advanced level
• Ethanol is heated with excess conc. H2SO4 at 443 K. The main product is: NEET level
• The ease of acid-catalysed dehydration of alcohols follows the order: NEET level
• 2-Bromopropane is heated with alcoholic KOH. The main product is: NEET level
• 1,2-Dibromoethane is treated with excess NaNH2 and then with water. The final product is: NEET level
• 3-Methylbutan-2-ol is heated with conc. H2SO4. The major alkene is: JEE Main level
• 2,2-Dimethylpropan-1-ol (neopentyl alcohol) is heated with conc. H2SO4. The main alkene formed is: JEE Main level
• Ethanol reacts with conc. H2SO4. Which statements are correct? JEE Main level
• Which statements about acid-catalysed dehydration of alcohols are correct? JEE Main level
• Why does alcoholic KOH favour elimination from 2-bromopropane whereas aqueous KOH gives mainly propan-2-ol? JEE Main level
• 1,1-Dibromopropane is heated with excess NaNH2 (3 equivalents) and the mixture is then treated with water. The product is: JEE Main level
• The order of ease of dehydrohalogenation by alcoholic KOH for ethyl bromide, isopropyl bromide and tert-butyl bromide is: JEE Main level
• 2-Methylcyclohexanol is heated with conc. H3PO4. The major alkene is: JEE Main level
• 2-Methylpentan-3-ol is dehydrated with conc. H2SO4 via the secondary carbocation at C3 and the tertiary carbocation formed from it by a 1,2-hydride shift. Count... JEE Advanced level
• trans-2-Methylcyclohexanol is treated with POCl3 in pyridine, which converts OH to a good leaving group and causes E2 anti elimination without carbocation. The ... JEE Advanced level
• 2,3-Dimethylbutane-2,3-diol (pinacol) is warmed with dilute H2SO4. The major product is: JEE Advanced level
• 1-Cyclobutylethanol, CH3CH(OH)-C4H7 (cyclobutyl attached to the carbinol carbon), is heated with conc. H3PO4. After the carbocation rearrangements that relieve ... JEE Advanced level
• 3-Hydroxybutanal is dehydrated in basic medium to but-2-enal by an E1cB pathway. Which statements are correct? JEE Advanced level
• Propene is treated with Br2 in CCl4, then with excess NaNH2 (3 equivalents) in liquid ammonia, and finally with CH3I. The final product is: JEE Advanced level
• Which alcohol is dehydrated most rapidly by dilute acid at the same temperature? JEE Advanced level
• 2,2-Dimethylcyclohexanol is heated with conc. H2SO4. The major alkene is: JEE Advanced level