Alkenes: preparation and addition reactions

38 questions on Alkenes: preparation and addition reactions from the Hydrocarbons chapter: 8 NEET level, 15 JEE Main, 15 JEE Advanced. Each one opens with its answer and solution.

• Ethanol is heated with excess concentrated H2SO4 at 443 K. The main product is NEET level
• Propene reacts with HBr in the absence of peroxide to give mainly NEET level
• Which reagent converts an alkyne into a cis-alkene? NEET level
• The reaction of an alkene with Br2 in CCl4 proceeds through which intermediate? NEET level
• 2-Bromobutane is heated with alcoholic KOH. According to Saytzeff's rule the major product is JEE Main level
• 2-Methylpropene reacts with HBr in the presence of benzoyl peroxide. The major product is JEE Main level
• 2-Methylbut-2-ene, (CH3)2C=CH-CH3, undergoes hydroboration with BH3.THF followed by H2O2/NaOH. The product is JEE Main level
• Cyclohexene reacts with bromine in the presence of water. The major product is JEE Main level
• 1,2-Dimethylcyclohexene is hydrogenated with H2 over Pt. The major product is JEE Main level
• 3-Methylbut-1-ene, CH2=CH-CH(CH3)2, reacts with HBr (no peroxide). The major product is JEE Main level
• Which of the following reagent sequences convert but-1-ene, CH3CH2CH=CH2, mainly into butan-2-ol? JEE Main level
• A hydrocarbon C5H10 gives 2-methylbutan-2-ol on oxymercuration-demercuration and a secondary alcohol on hydroboration-oxidation. The hydrocarbon is JEE Advanced level
• But-1-ene is treated with HBr (no peroxide) to give A. A is heated with alcoholic KOH to give B as the major product. B is treated with O3 and then Zn/H2O to gi... JEE Advanced level
• (Z)-But-2-ene is (i) treated with cold dilute alkaline KMnO4 to give the diol P, and (ii) treated with Br2 in CCl4 to give the dibromide Q. Which pair is correc... JEE Advanced level
• 2-Bromo-2,3-dimethylbutane, (CH3)2CBr-CH(CH3)2, is treated separately with sodium ethoxide in ethanol and with potassium tert-butoxide in tert-butanol. The majo... JEE Advanced level
• Consider the alkenes (I) ethene, (II) propene, (III) 2-methylpropene and (IV) 3,3,3-trifluoropropene. The order of reactivity towards electrophilic addition of ... JEE Advanced level
• Which of the following statements are correct? JEE Advanced level
• In which of the following reactions is the major product formed with a rearranged carbon skeleton (compared with the starting alkene)? JEE Advanced level
• Propene reacts with HBr in the absence of any peroxide. The major product is NEET level
• Which reagent combination converts propene into propan-1-ol as the major product? NEET level
• Ethene is bubbled through a solution of bromine in CCl4. The red-brown colour disappears and the product formed is NEET level
• Ethanol is heated with excess concentrated H2SO4 at 443 K. The main organic product is NEET level
• On heating with concentrated H2SO4, 2-methylbutan-2-ol gives mainly JEE Main level
• 2-Methylbut-2-ene is treated with O3 and the ozonide is then worked up with Zn/H2O. The organic products are JEE Main level
• 3-Methylbut-1-ene reacts with HBr in the dark. The major product is JEE Main level
• Which of the following alkenes give propanone as one of the organic products on ozonolysis followed by reductive work-up (Zn/H2O)? Select all that apply. JEE Main level
• cis-But-2-ene is treated with cold, dilute, alkaline KMnO4. The product is JEE Main level
• trans-But-2-ene is treated with bromine in CCl4. The product is JEE Main level
• Count the acyclic alkenes of molecular formula C6H12 that give 3-methylpentane on catalytic hydrogenation. Count (E) and (Z) isomers separately, and do not coun... JEE Main level
• Which of the following correctly describe the reaction of 2-methylpropene, (CH3)2C=CH2? Select all that apply. JEE Main level
• An alkene X (C7H14) gives propanone and butanal on ozonolysis with reductive work-up. X is treated with HBr in the presence of an organic peroxide. The major pr... JEE Advanced level
• 1-Methylcyclohexene is subjected to (i) BH3 in THF; (ii) H2O2, NaOH. The major product (racemic) is JEE Advanced level
• Cyclohexene is treated with bromine, with methanol as the solvent in large excess. The major product is JEE Advanced level
• 2-Bromo-2,3-dimethylbutane is heated separately with (X) alcoholic KOH and (Y) potassium tert-butoxide in tert-butanol. Taking Saytzeff elimination with the sma... JEE Advanced level
• Which of the following alkenes give 2,3-dimethylbutane on catalytic hydrogenation over Pd/C? Select all that apply. JEE Advanced level
• Compound P (C6H12) gives propanone and propanal on ozonolysis with reductive work-up. P is treated with (i) BH3 in THF, (ii) H2O2/NaOH to give Q, and Q is heate... JEE Advanced level
• 3,3-Dimethylbut-1-ene reacts with HCl at low temperature. The major product is JEE Advanced level
• Which of the following methods convert (E)-but-2-ene into meso-butane-2,3-diol? Select all that apply. JEE Advanced level