L Le ev ve el l 2 2 – – C Ca as se e 2 29 9
S St te er re eo os se el le ec ct ti iv ve e D De eb br ro om mi in na at ti io on n o of f
V Vi ic ci in na al l D Di ib br ro om mi id de es s
K Ke ey y p po oi in nt t: : S St te te t te te te te t ter re re r re re re re r reo oc ch he em mi is is i is is is i i t tr t tr tr tr tr t t y
ry ry y
Br
Br
R
Te T T
R
'
Br
Te T
Br
R
R
R = Alkyl, Aryl
S St te er re eo os se el le ec ct ti iv ve e D De eb br ro om mi in na at ti io on n o of f V Vi ic ci in na al l D Di ib br ro om mi id de es s
Organotellurides 1 have been used in debromination of vicinal (vic) dibromides.
The reaction takes place by heating the dibromide and the organotelluride in
CHCl 3 or CH 3 CN at 90–100°C as shown in Scheme 29.1.
Br
Br
R
Te T T
R
'
Br
Te T
Br
R
R
1 R = Alkyl, Aryl
Scheme 29.1
Mechanisms 1 and 2 have been proposed to explain the role of the tellurides in
these reactions.
Comment both options and discuss the experimental data justifying which of the
proposed mechanisms seems to be more likely.
Br
Br
Br
TeR 2
MECHANISM 1
Te
Br R
R
Br
Te
Br
R
R
TeR 2
Br
Br