Banaras Hindu University (BHU) 2006 B.Sc Chemistry .part 2 - Question Paper

organic chemistry



ans any 2 ques. from part a and any 4 from sectionA part B part C is compulsory
part _a

1) how the subsequent conversion can done? [MARKS 4*21/2]

(A)C4H8O4------------------->C5H10O5+C5H10O5( EPIMERS)

(B)C6H5Br------------------>C6H5COOH

(C)RCH2NH2--------------->RNH2

(D)C6H5OH_____________>HO-C6H4N=N-Ph


2.EXPLAIN THE subsequent OBSERVATION;; [MARKS 4*21/2]


(A)ANILINE IS MORE REACTIVE THAN ACETANILIDE IN ELECTROPHILIC SUBSTITUTION.

(B) C6H6ClIS FAR LESS REACTIVE IN ELECTROPHILIC AROMATIC SUBSTITUTION ALTHOUGH Cl AND N HAVE ALMOST identical ELECTRONEGETIVITY

(C) 2,4,6 TRINITROPHENOL REACT WITH Aq. NaHCO3 BUT PHENOL DOES NOT

(D) FRIEDEL CRAFT REACTION REACTION FAILS WITH ANILINE ALTHOUGH AMINO GROUP IS ACTIVATING

3.
(A)WRITE AN formula FOR THE GENERATION OF +NO2 FROM HNO3 IN THE PRESENCE OF H2SO4 [MARKS 3]

(B)DRAW SUITABLE MECHANISMS FOR THE subsequent REACTIONS []
()C6H6OH +CH2O-------+H-------.>RESIN

()C4H4N___KOH/CHCl3____________>C5H5ClN


4. ELECTROPHILIC SUBSTITUTION IN THIOPHENE OCCURS MAINLY AT C-2 POSITION .DiscUSS. [MARKS 5]


5.DiscUSS THE ORDER OF AROMATICITY AND REACTIVITY AMONG FURAN THIOPHENE BENZENE AND PYRROLE.[MARKS 5]


6.WRITE SHORT NOTES ON ANY 2 OF THE FOLLOWING; .[MARKS 2*1/2]

(A) OCTANE NUMBER

(B)CRACKING

(C)MUTAROTATION

(D) HINSBERG TEST FOR AMINES


7.DiscUSS NUCLEOPHILIC SUBSTITUTION IN PYRIDINE [MARKS 5]


8.EXPLAIN WHY THE C-2 EPIMER IN ALDOSES provide THE identical OSAZONE.[MARKS 5]


9. discuss BRIEFLY THE EFFECT OF SUBSTITUENTS ON REACTIVITY AND ORIENTATION IN AROMATIC ELECTROPHILIC REACTIONS.[MARKS 5]



part _c

10. (A)an aromatic compound A(C8H8O) UPON TREATMENT WITH ALKALINE SOLUTION OF IODINE FORMS A YELLOW PRECIPITATE.THE FILTRATE ON ACIDIFICATION provide AWHITE SOLID B( C7H6O2) . WRITE THE STRUCTURE OF A AND B.EXPLAIN THE REACTIONS,[MARKS 4]

(B)COMPOUND REACT WITH CHLORINE WITH IN THE PRESENCE OF UV LIGHT TO provide A PRODUCT WHICH ON HYDROLYSIS FORMS BCOMPOUND UNDERGOES PERKIN REACTION WITH Ac2O AND AcONa
TO PRODUCE AN ACID C( C9H8O2).WHAT ARE THE COMPOUND A ,B AND C?EXPLAIN THE REACTION INVOLVED.[MARKS 6]

Earning:   Approval pending.