University of Delhi 2010-2nd Year M.Tech Information Technology 1st nd sem reagents in organic synthesis newer synthetic reactions and methodologies UNIVERSITY - Question Paper

[This question paper contains 6 printed pages]

Your Roll No

7645    J

M.Tech./II Sem.

CHEMICAL SYNTHESIS AND PROCESS _t    TECHNOLOGIES

Paper-201-Reagents m Organic Synthesis, Newer Synthetic Reactions and Methodologies

Time 3 Hours '    Maximum Marks . 70

(Write your Roll No on the top immediately on receipt of this question paper )

Use separate answer script for section A and B SECTION-A

Answer all questions, Do not discuss mechanisms unless asked for State the principle and/or concept involved m the reactions Write neat perspective structural diagrams 1 (a) How is Wilkinson's catalyst prepared⁹

(b) When an alkene (RCH=CHR) is hydrogenated using a mixture of D₂ and H₂, the product (RCH₂CH₂R) contains molecules RCHD CHD R and RCH₂CH₂R only⁹ There are no molecules containing D and H (RCHD CH₂R) Account

How is borane prepared from sodium borohydride⁹ Compare alkyl boranes and Gngnard reagents in their chemical reactivity

Select a hydride transfering agent which can be used to convert a carbonyl to methylene Write all the steps

Compare the reactivity of sodium borohydnde and LAH towards a conjugated ketone Solve any two

(i)
H

PhCOCRBr ₎ ? BOH + Bu'OK

(a) Solve the following problems based on the concepts of vinyl silanes and allyl silanes

CHgCOCl -> AlClg 90 C

(b) Recall the chemistry of enol silyl ethers, work out the following

/XOSiMeg

(1) Cyclohexanone

CH₂=NMe* f

(I)    Peterson Reaction

(II)    Wacker Oxidation (m) Heck Reaction

(iv)    Suzuki Cross coupling

(v)    Trialkyl silyl halides (Cl, Br, I) in organic synthesis

SECTION-B Attempt any five questions Explain the term Umpolung synthesis Give the synthesis of 4-methylpent-3-ene involving acyl anion equivalent of

1,3-dithiane    2+5

Write the mechanism of any two of the following reactions    3 5+3 5

(I)    Arbuzov rearrangement

(II)    Mukaiyama-Johnson aldol reaction

(III)    Horner-Wadsworth-Emmons reaction or Wittig reaction of stabilized yields

( 5 )    7645

Predict the products (s) formed in each of the following reactions    2+5

raney Ni C- D

Explain any two    3 5 + 3.5

(l) Why enamines are nucleophilic⁷ Give one example (n) Why clay-supported PTC is better than polymer-supported PTC⁷ (m) Why Z-enolates give syn-aldol products and E-enolates give anti-aldol products⁷ Explain on the basis of Zimmerman-Traxler model Explain the action of the mimic of Ribonuclease A system in the hydrolysis of the phosphates    7

6    Predict the product formed by the reaction of acrylamide (a weak Michael acceptor) and aromatic aldehydes such as 2-formylthiazole at room temperature in an aqueous medium (l,4-dioxanel/H₂0) (1 1) in the presence of a stoichiometric amount of DABCO Write the name of reaction involved and its mechanism    3+1+3

7    (a) The sulphomum salt [B] formation was carried out

by treating the precursor thiol [A] with C₇H₇Br [C], followed by addition of AgC10₄ The reaction of B with D (aldehyde) gives the compound E and recovered compound A Complete the reactions involved m this synthesis

	+ A
A E

(b) Write structures for the following compounds

(i) DBU

(n) Common ammonium or phosphomum salts used

as PTC

(m) Dicyclohexano-18*crown-6

100

Attachment: university-of-delhi-2010-m-tech-information-technology-35321-1.pdf

Earning:   Approval pending.