Handbook of Solvents - George Wypych - ChemTech - Ventech!

13.3 Effects of organic solvents on phase-transfer catalysis 819
[13.3.13]
The effect of organic solvent on the two-phase polycondensation is shown in Table
13.3.15. Chloroform, 1,2-dichloroethane, nitrobenzene, acetophenone and anisole were all
effective as the polymerization media to produce moderate molecular weight polymer
(VII).
Table 13.3.15. Synthesis of aromatic polyether VII in various organic solvent/water
system with DC-18-C-6 catalyst
Solvent Reaction temp., o C Reaction time, h Polymer [η], dLg -1 *
CH2Cl2 20 24 0.84
CHCl3 20 24 0.53
CH2ClCH2Cl 20 24 0.42
C6H5NO2 20 24 0.47
C6H5NO2 80 2 0.51
C6H5NO2 100 1 0.42
Data obtained from the work of Imai; 41 Reaction conditions: 2.5 mmol of II, 2.5 mmol of VI, 0.05 mmol of
DC-18-C-6 in 3.5 mL of solvent, and 5 mL of KOH (1.01 M) solution, *Measured at a concentration of 0.5 dLg -1 in
DMF at 30 o C
A convenient method for the preparation of polysulfides by the two-phase
polycondensation in a KOH solution is known. 41 Polycondensation of 1,4-dibromobutane
(VIII) and 1,6-hexanedithiol (IX) leading to polysulfide (X) was carried out in various organic
solvent/H 2O system with DC-18-C-6 catalyst.
[ ]
( ) ( ) ( ) ( )
Br CH2 Br + HS CH
4 2 SH →
6
− CH2 −S− 4
CH2 −S− 6
VIII IX X
n
[13.3.14]
The results of the polycondensation are given in Table 13.3.16. All polymerization
media employed produced polysulfide with moderately high inherent viscosities; whereas
the polymer with the highest viscosity was produced in the absence of organic solvents.
Polycondensation conducted in the presence of any catalyst in this system led to the formation
of a polymer with moderately high molecular weight.