Claisen-Schmidt Reaction:
In this exercise, you will make 2,2,6-trimethyl-5-phenylheptan-3-one by a reaction sequence which involves a Claisen-Schmidt Reaction followed by the 1,4-addition of a Grignard reagent to a conjugated ketone:
Stage 1
C6H5-CH=O + CH3-CO-C(CH3)3 ----> C6H5-CH=CH-CO-C(CH3)3 + H2O
Stage 2
(CH3)2CH-Br + Mg ----------> (CH3)2CH-Mg-Br
C6H5-CH=CH-CO-C(CH3)3 ----------> C6H5-CH-CH2-CO-C(CH3)3
The reactions will give you experience of a number of techniques and concepts. These include
(a) use of extended reaction times;
(b) distillation under reduced pressure (‘vacuum distillation');
(c) working in a water-free system;
(d) differences in the IR absorption frequencies of conjugated and non-conjugated ketones;
(e) use of NMR in the determination of stereochemistry and structure
Safety : general
Carry out all work in a fume-cupboard, and observe normal good laboratory practice. Wear eye-protection, a buttoned-up lab-coat and gloves throughout this exercise. Treat all organic compounds as flammable, and do not bring them into direct contact with ignition sources. Ether is highly flammable: always work in a fume-hood and segregate totally from any work that uses naked flames.