Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
JEE Main202430 Jan 2024Morning ShiftChemistryHydrocarbonsActual

In the given reactions identify the reagent A and reagent B

Options

  1. AA - CrO 3 B - CrO 3
  2. BA - CrO 3 B - CrO 2 Cl 2
  3. CA - CrO 2 Cl 2 B - CrO 2 Cl 2
  4. DA - CrO 2 Cl 2 B - CrO 3

Correct answer

B. A - CrO 3 B - CrO 2 Cl 2

Step-by-step solution

Toluene or substituted toluene is converted to benzylidene diacetate on treating with chromic oxide in acetic anhydride. The benzylidene diacetate can be hydrolysed to corresponding benzaldehyde with aqueous acid. Chromyl chloride oxidises methyl group to a chromium complex, which on hydrolysis gives corresponding benzaldehyde. The reaction is known as Etard reaction.

Practice Hydrocarbons on Quantrex Academy →

More from Hydrocarbons

In the following reaction sequence, Q , R , S and T are the major products. The correct statement(s) about Q , R , S and T is(are) 2026Treatment of buta-1,3-diyne with NaNH ₂ ( 2 equivalents), followed by reaction with excess of trans - CH ₃ -CH=CH-CH ₂ -Br gives X as the major product. The maximum number of carbo 2026The List-II contains products obtained from the reaction of compounds in List-I with O ₃ /Zn- H ₂ O followed by cyclization (via more stable enolate) in the presence of aqueous NaO 2026Natural rubber on complete ozonolysis ( O ₃ /Zn- H ₂ O ) gives compound X as the major product. X gives positive iodoform and Tollen's tests. X on heating with aqueous NaOH gives Y 2026An optically active alkyl bromide C₄ H₉ Br, reacts with ethanolic KOH to form major compound [A] which reacts with bromine to give compound [B]. Compound [B] reacts with ethanolic 2026An alkane (Y) requires 8 moles of oxygen for complete combustion and on chlorination with Cl₂ /h , (Y) gives only one monochlorinated product (Z) . The total number of primary carb 2026R_f value for 2 -methylpropene in a solvent system (Ethyl acetate + ether) is 0.42 . 2 -methylpropene is treated with dilute H ₂ SO ₄ to give major organic product (X). R_f value f 2026Given below are two statements: Statement I: Methane can be prepared by decarboxylation of sodium ethanoate, Kolbe's electrolysis of sodium acetate and reaction of CH ₃ MgBr with w 2026 Full Hydrocarbons list All JEE Main PYQs