types of hydrogen it contains. Compound containing only one type of hydrogen gives only one
monohalogenation product.
CH
3
CH
2
CH
3
— two types of hydrogen
propane (two monohalogenation structural product)
CH
3
CH
2
CH
2
CH
2
CH
3
— three types of hydrogen
pentane (two monohalogenation structural product)
— four types of hydrogen (four monohalogenation structural product)
— one types of hydrogen (one monohalogenation structural product)
Thus the given alkane should be neopentane.
47. The prussian blue colour obtained during the test of nitrogen by Lassaigne’s test is due to the formation of :
[AIEEE 2004]
(A*) Fe
4
[Fe(CN)
6
]
3
(B) Na
3
[Fe(CN)
6
] (C) Fe(CN)
3
(D) Na
4
(Fe(CN)
5
NOS]
Sol. 6NaCN + FeSO
4
Na
4
[Fe(CN)
6
]
Na
4
[Fe(CN)
6
] + 4Fe
3+
xH
2
O
Fe
4
[Fe(CN)
6
]
3
. xH
2
O
Ferric ferrocyanide (Prussian blue)
48. Of the five isomeric hexanes,the isomer which can give two monochlorinated compounds is ?
[AIEEE 2005]
(1) n–Hexane (2*) 2,3-Dimethylbutane (3) 2,2-Dimethylbutane (4) 2-Methylpentane
Sol. 2,3-Dimethylbutane has two chemically different hydrogen atoms so it can give two monochlorinated
structural compounds.
49. Alkyl halides react with dialkyl copper reagents to give [AIEEE 2005]
(1) alkenes (2) alkyl copper halides (3*) alkanes (4) alkenyl halides
Sol. In Corey house synthesis of alkane, alkyl halide reacts with lithium dialkyl cuprate.
R CULi + R’X RR’ + RCu + LiX
50. Reaction of one molecule of HBr with one molecule of 1, 3-butadiene at 40°C gives predominantly
(1) 3-bromobutene under kinetically controlled conditions [AIEEE 2005]
(2*) 1-bromo-2-butene under thermodynamically controlled conditions
(3) 3-bromobutene under thermodynamically controlled conditions.
(4) 1-bromo-2-butene under kinetically controlled conditions.
Sol. 1, 2-addition product is kinetically controlled product while 1, 4-addition product is thermodynamically controlled
product and formed at comparitively higher temperature.
CH
2
= CH – CH = CH
2
CH
2
(Br) CH = CHCH
3
+ CH
3
CH(Br) – CH = CH
2
1, 4–addition 1, 2–addition
Therefore, 1 - bromo-2-butene will be the main product under themodynamically dcontrolled conditions.
51. Elimination of HBr from 2-bromobutane result in the formation of : [AIEEE-2005]
(1) Predominantly 2-butyne (2) Predominantly 1-butene
(3*) Predominantly 2-butene (4) Equimolar mixture of 1 and 2-butene
Sol.
52. Reaction of trans 2–phenyl –1 – bromocyclopentane on reaction with alcoholic KOH produces:
[AIEEE-2006]