Question 1

Consider the following reaction, and choose the correct option.

Accepted Answer

The given reaction is the Etard reaction. Toluene reacts with chromyl chloride ( CrO _2 Cl _2) in a non-polar solvent like CS _2 to form a chromium complex, which upon acid hydrolysis ( H _3 O ^+) yields benzaldehyde. Therefore, compound P is benzaldehyde ( C _6 H _5 CHO ). Let us evaluate the given options: Option (1): The hydrogenation of benzoyl chloride ( C _6 H _5 COCl ) with H _2 in the presence of Pd supported on BaSO _4 is known as the Rosenmund reduction. This reaction yields benzaldehy

Question 2

Given below are two statements: Statement I: trans -But-2-ene upon treatment with Br_2 in CCl_4 gives the following product cis -But-2-ene upon treatment with alkaline KMnO_4 gives the following produ

Accepted Answer

Reaction of trans-but-2-ene with Br_2 in CCl_4 proceeds via anti-addition to give meso-2,3-dibromobutane. In the Newman projection given in Statement I, the front carbon has Br at 0^ , Me at 120^ , and H at 240^ . The back carbon has Br at 180^ , Me at 60^ , and H at 300^ . For this staggered conformation to be meso, it must have a center of inversion, meaning a group at angle on the front carbon must have an identical group at + 180^ on the back carbon. While the Br atoms are opposite (0^ and 1

Question 3

Among the following, the compound having conjugated double bonds is

Accepted Answer

Conjugated double bonds are separated by exactly one single bond. In hepta-1,6-diene, the double bonds are at C1 and C6, separated by three single bonds. In hepta-1,3-diene, the double bonds are at C1 and C3, separated by exactly one single bond (between C2 and C3). Thus, it has conjugated double bonds. In hepta-1,4-diene, the double bonds are at C1 and C4, separated by two single bonds. In hepta-1,5-diene, the double bonds are at C1 and C5, separated by three single bonds. Answer: hepta-1,3-die

Question 4

For the following reaction sequence, choose the correct option

Accepted Answer

The first step is the Friedel-Crafts acylation of benzene with acetyl chloride ( CH _3 COCl ) and anhydrous AlCl _3, which produces acetophenone ( C _6 H _5 COCH _3). The second step is the haloform reaction. Acetophenone has a methyl ketone group and reacts with sodium hypochlorite ( NaOCl ) to form sodium benzoate ( C _6 H _5 COONa ) and chloroform ( CHCl _3). Thus, the products P and Q are sodium benzoate and chloroform. Sodium benzoate ( P ) on acidification yields benzoic acid ( C _6 H _5 C

Question 5

Two products X and Y are formed in the following reaction sequence. C _6 H _6 + CH _3 Cl Anhydr. AlCl _3 W [ warm ] dil. HNO _3 + dil. H _2 SO _4 X + Y The suitable method that can be used for the sep

Accepted Answer

The reaction of benzene with methyl chloride in the presence of anhydrous AlCl _3 is a Friedel-Crafts alkylation, which yields toluene (W). C _6 H _6 + CH _3 Cl Anhydr. AlCl _3 C _6 H _5 CH _3 Nitration of toluene with a mixture of HNO _3 and H _2 SO _4 yields a mixture of ortho-nitrotoluene and para-nitrotoluene as the major products (X and Y). C _6 H _5 CH _3 [ warm ] dil. HNO _3 + dil. H _2 SO _4 o-nitrotoluene + p-nitrotoluene The boiling point of o-nitrotoluene is 222^ C and that of p-nitro

Question 6

The number of chlorine atoms present in the organic products X and Y of the following reactions, respectively, are : C _6 H _6 + 6 Cl _2 [ dark, cold ] Anhydr. AlCl _3 X C _6 H _6 + 3 Cl _2 [500\ K ]

Accepted Answer

Reaction 1 is an electrophilic aromatic substitution. Benzene reacts with excess chlorine in the presence of anhydrous AlCl _3 (a Lewis acid) to form hexachlorobenzene ( C _6 Cl _6). C _6 H _6 + 6 Cl _2 [ dark, cold ] Anhydr. AlCl _3 C _6 Cl _6 + 6 HCl The organic product X is hexachlorobenzene, which contains 6 chlorine atoms. Reaction 2 is a free radical addition reaction. Benzene reacts with chlorine in the presence of UV light to form benzene hexachloride ( C _6 H _6 Cl _6), also known as ga

Question 7

Consider the following reaction sequences and choose the correct option.

Accepted Answer

The given starting material is 1-phenylpropyne, Ph - C C - Me . Reduction of the alkyne with H _2 in the presence of Lindlar's catalyst ( Pd/C poisoned with BaSO _4 or quinoline) proceeds via syn-addition. This yields the cis-alkene. Therefore, K is cis-1-phenylpropene. Reduction of the alkyne with Na in liquid NH _3 (Birch reduction conditions) proceeds via anti-addition. This yields the trans-alkene. Therefore, L is trans-1-phenylpropene. Since K is the cis-isomer and L is the trans-isomer of

Question 8

Which one of the following compounds does not decolourize bromine water?

Accepted Answer

Bromine water solution is decolourised in reaction (1), (2), (3) but not in (4).

Question 9

Which one of the following reactions does NOT give benzene as the product?

Accepted Answer

Answer option index: 3

Question 10

The major product X formed in the following reaction sequence is:

Accepted Answer

Answer option index: 2

Question 11

The alkane that can be oxidized to the corresponding alcohol by KMnO _4 as per the equation is, when:

Accepted Answer

Generally alkanes resist oxidation but alkane with tertiary H atom(s) can be oxidised to corresponding alcohols by KMnO _4 R _1 CH _3 R _2 CH _3 R _3 CH _3

Question 12

Identify the correct reagents that would bring about the following transformation.

Accepted Answer

Mechanism:

Hydrocarbons — Previous Year Questions & Solutions