20.2 Outline a procedure for separating a mixture

NH(C 2H 5) 2
CH 3CH 2COCl
AlCl 3
O
O
N(C2H5)2
CH 2CH 3
Br 2
O
CHCH 3
20.47 Suggest an experiment to test the proposition that the Hofmann reaction is an intramolecular
rearrangenment, i.e.,one in which the migrating R group never fully separates from the amide
molecule.
A:
C 6H 5H 2C
O
CNH2
Br 2, NaOH, H 2O
C6H5H2C
H3C H
H3C
H
From the example above, the R group migrates to nitrogen with its electrons, but without
inversion.
20.48 Using as starting materials propanoic acid, aniline, and 2-naphthol, propose a synthesis of
naproanilide, a herbicide used in rice paddies in the Orient.
OH
O
OH
Cl 2
P
Cl
Cl
O
O
Cl
NH 2
20.49 When phenyl is isothiocyanate, C6H5N=C=S, is reduced with lithium aluminum hydride,
the product formed has these spectral data:
MS (m/z): 107, 106
IR (cm -1 ): 3330(sharp), 3050, 2815, 760, 700
1
H NMR (δ ): 2.7(s), 3.5(board), 6.6(m), 7.2(t)
13
C NMR (δ ): 30(CH2), 112(CH), 117(CH), 129(CH2), 150(C)
(a) What is the structure of the product?
(b) What is the structure that account for the 106m/z peak and how is it formed? (It is an iminium
O
O
Cl
N
H
H
N
NH 2
Br