Page 96 - Catalysts for Fine Chemical Synthesis Vol 1 - Robert & Poignant

82 hydrolysis, oxidation and reduction

Procedure

1. The tartaric acid, 1,8-octanediol and p-toluene sulfonic acid were placed in the
flask and the latter flushed with N 2 . A positive pressure of N 2 was then
maintained throughout. The mixture was stirred as the temperaturewas raised
to 140 8C to achieve a homogeneous solution; the temperature was then
allowed to fall to 125 8C and the reaction left to proceed for 3 days.
2. Water and excess diol were removed by distillation under high vacuum to
yield a solid mass. The latter was swollen in refluxing ethyl acetate (sufficient
to make the mass mobile) and the resulting mixture poured into n-hexane
( 3 fold volume excess).
3. The solid was recovered by decanting off the solvents and the polymer dried
under vacuum at 40 8C for 6 hours and at room temperature for 2 days to
yield 16.6 g (95 %) of poly(octamethylene tartrate) (3).
[a] D 25 ˆ ‡9 (c 1.6, THF).
1 H NMR (400 MHz, DMSO-d 6 , 70 8C): d 5.75 (br s), 5.41 (d, J3.2 Hz), 4.62
(d, J 2.9 Hz), 4.37 (s, 2H), 4.09 (t, J 6.5 Hz, 4H), 1.58 (m, 4H), 1.30 (m, 9H).
Note 1 ± small signals d ˆ 5:41 and 4.62 correspond to methine H atoms on
tartrate branch points; the ratio of these intensities to the total intensity of all
tartrate methine resonances allows estimation of the percentage branching.
Note 2 ± the percentage branching can vary with precise reaction condi-
tions, up to ~ 10 % gives optimal results; products insoluble in DMSO are
crosslinked and should be discarded.
ÿ1
FTIR (KBr, cm ) 3450 (OH), 2932, 2857 (C±H aliphatic), 1743 (CˆO
ester).
Poly(octamethylene tartrate) can be used directly in place of dialkyl
tartrates in the Sharpless epoxidation of allylic alcohols.

5.3.2 ASYMMETRIC EPOXIDATION OF (E)-UNDEC-2-EN-1-OL

poly(tartrate) O
R OH R OH
Ti(OiPr) 4
(4b) TBHP (5b)

R = C 3 H 7 , (4a,5a); C 8 H 17 , (4b,5b); Ph (4c,5c) (see Table 5.2)

Materials and equipment
. Dry CH 2 Cl 2 (over CaCl 2 )
Ê
. Powdered activated 4 A molecular sieves