Sign in
12thPass logo
New chatPYQ LibraryDoubtsRank report
Sign in to see Recents

Your guest activity stays on this device

Sign in to save progress →
Sign in

Compounds Containing Nitrogen question

2021 · Shift 1 · Q12
Guest · filters and generic practice availableBrowsing as a guest · PYQ filters and generic practice are available. Sign in only for personalised features and saved progress.
  1. PYQ Library
  2. /JEE Advanced
  3. /Chemistry
  4. /Compounds Containing Nitrogen
  5. /2021 · Shift 1 · Q12

Compounds Containing Nitrogen question

2021 · Shift 1 · Q12

JEE AdvancedChemistryCompounds Containing NitrogenMultiple correct+4 / −2
The reaction of Q with PhSNa yields an organic compound (major product) that gives positive Carius test on treatment with Na2O2Na_2O_2Na2​O2​ followed by addition of BaCl2BaCl_2BaCl2​. The correct option(s) for Q is (are)
  1. A
    JEE Advanced 2021 Paper 1 Online Chemistry - Compounds Containing Nitrogen Question 27 English Option 1
  2. B
    JEE Advanced 2021 Paper 1 Online Chemistry - Compounds Containing Nitrogen Question 27 English Option 2
  3. C
    JEE Advanced 2021 Paper 1 Online Chemistry - Compounds Containing Nitrogen Question 27 English Option 3
  4. D
    JEE Advanced 2021 Paper 1 Online Chemistry - Compounds Containing Nitrogen Question 27 English Option 4
View written solutionFree

Correct answer: A, D

Step-by-step Derivations:

  1. Analyze the Question's Core Requirement: The question asks to identify the starting compound(s) Q which, upon reaction with sodium thiophenoxide (PhSNa), yield a major organic product containing sulfur. A compound containing sulfur will give a positive Carius test. The Carius test involves oxidizing the organic compound with Na2O2Na_2O_2Na2​O2​ (or fuming nitric acid), which converts sulfur into sulfuric acid/sulfate. Subsequent addition of BaCl2BaCl_2BaCl2​ precipitates the sulfate as white BaSO4BaSO_4BaSO4​.

    The central task is to predict the major product of the reaction between each option Q and PhSNa and check if it contains sulfur.

  2. Analyze the Reagent: PhSNa is sodium thiophenoxide. It is a source of the strong, soft nucleophile, thiophenoxide ion (PhS−PhS^-PhS−). It will participate in nucleophilic substitution reactions.

  3. Evaluate Each Option:

    • Option A: Q is benzhydryl chloride (Ph2CHClPh_2CHClPh2​CHCl). This is a secondary benzylic halide. The reaction is a nucleophilic substitution where the PhS−PhS^-PhS− nucleophile replaces the chloride (Cl−Cl^-Cl−) leaving group. Ph2CHCl+PhSNa→Ph2CH−SPh+NaClPh_2CHCl + PhSNa \rightarrow Ph_2CH-SPh + NaClPh2​CHCl+PhSNa→Ph2​CH−SPh+NaCl The carbocation intermediate (Ph2CH+Ph_2CH^+Ph2​CH+) is highly stabilized by two phenyl rings, favoring an SN1S_N1SN​1 mechanism, while the strong nucleophile PhS−PhS^-PhS− also allows for an SN2S_N2SN​2 pathway. Regardless of the mechanism, the substitution product, diphenylmethyl phenyl sulfide (Ph2CH−SPhPh_2CH-SPhPh2​CH−SPh), is the major product. This product contains sulfur. Therefore, it will give a positive Carius test. Option A is correct.

    • Option B: Q is benzoyl chloride (PhCOCl). This is an acyl chloride. The reaction is a nucleophilic acyl substitution. The PhS−PhS^-PhS− attacks the electrophilic carbonyl carbon, and Cl−Cl^-Cl− is eliminated. PhCOCl+PhSNa→PhCO−SPh+NaClPhCOCl + PhSNa \rightarrow PhCO-SPh + NaClPhCOCl+PhSNa→PhCO−SPh+NaCl The product is S-phenyl thiobenzoate, which contains sulfur. However, acyl chlorides are extremely reactive and readily hydrolyze, even with trace amounts of moisture that might be present in the solvent or if the PhSNa was prepared in a protic solvent. PhCOCl+H2O→PhCOOH+HClPhCOCl + H_2O \rightarrow PhCOOH + HClPhCOCl+H2​O→PhCOOH+HCl The hydrolysis of benzoyl chloride is a very fast reaction. It's plausible that under typical (non-anhydrous) laboratory conditions, the competing hydrolysis reaction could lead to benzoic acid (PhCOOH) as the major product. Since benzoic acid does not contain sulfur, it would not give a positive Carius test. Given the high reactivity of PhCOCl towards water compared to other substrates, it is reasonable to assume hydrolysis could be the dominant pathway, making the desired sulfur-containing compound a minor product. Therefore, Option B is likely incorrect as per the 'major product' condition.

    • Option C: Q is N,N-dimethylformamide (HCONMe2HCONMe_2HCONMe2​). This is an amide. Amides are significantly less reactive towards nucleophilic substitution than acyl chlorides or alkyl halides. The leaving group would be the dimethylamide anion ((CH3)2N−(CH_3)_2N^-(CH3​)2​N−), which is a very strong base and thus a very poor leaving group. No significant reaction is expected to occur between DMF and PhSNa under normal conditions. HCONMe2+PhSNa→No ReactionHCONMe_2 + PhSNa \rightarrow No \, ReactionHCONMe2​+PhSNa→NoReaction Thus, no sulfur-containing product is formed. Option C is incorrect.

    • Option D: Q is benzenesulfonyl chloride (PhSO2ClPhSO_2ClPhSO2​Cl). This is a sulfonyl chloride. The reaction is a nucleophilic substitution at the electrophilic sulfur atom. The PhS−PhS^-PhS− nucleophile attacks the sulfur, and Cl−Cl^-Cl− is eliminated. PhSO2Cl+PhSNa→PhSO2−SPh+NaClPhSO_2Cl + PhSNa \rightarrow PhSO_2-SPh + NaClPhSO2​Cl+PhSNa→PhSO2​−SPh+NaCl The product is S-phenyl benzenethiosulfonate. While sulfonyl chlorides can also undergo hydrolysis, they are generally less reactive towards water than acyl chlorides. The reaction with a strong nucleophile like PhS−PhS^-PhS− is efficient and expected to yield the sulfur-containing compound as the major product. This product contains sulfur and will give a positive Carius test. Option D is correct.

  4. Conclusion: Based on the analysis, the substrates in options A and D will react with PhSNa to form major products containing sulfur. The substrate in option B is highly susceptible to hydrolysis, which may result in a non-sulfur-containing major product. The substrate in option C is unreactive. Therefore, the correct options are A and D.

PreviousNext

More from Compounds Containing Nitrogen

  • The reaction sequence(s) that would lead to o-xylene as the major product is(are)2021 · Multiple correct
  • Reaction of x g of Sn with HCl quantitatively produced a salt. Entire amount of the salt reacted with y g of nitrobenzene in the presence of required amount of HCl to produce 1.29 g of an organic salt (quantitatively). (Use Molar masses…2021 · Numerical
  • Correct option(s) for the following sequence of reactions is(are) Includes diagram2021 · Multiple correct
  • Reaction of x g of Sn with HCl quantitatively produced a salt. Entire amount of the salt reacted with y g of nitrobenzene in the presence of required amount of HCl to produce 1.29 g of an organic salt (quantitatively). (Use Molar masses…2021 · Numerical
  • Consider the reaction sequence from P to Q shown below. The overall yield of the major product Q from P is 75%. What is the amount in grams of Q obtained from 9.3 mL of P? (Use density of P = 1.00 g mL-1; Molar mass of C = 12.0, H = 1.0, O… Includes diagram2020 · Numerical
  • Schemes 1 and 2 describe the conversion of P to Q and R to S, respectively. Scheme 3 describes the synthesis of T from Q and S. The total number of Br atoms in a molecule of T is ................. Includes diagram2019 · Numerical
  • Aniline reacts with mixed acid (conc. HNO3​ and conc. H2​SO4​) at 288K to give P (51%), Q (47%) and R (2%). The major product(s) of the following reaction sequence… Includes diagram2018 · Multiple correct
  • The order of basicity among the following compounds is Includes diagram2017 · MCQ