Handbook of Solvents - George Wypych - ChemTech - Ventech!

808 Maw-Ling Wang
Table 13.3.5. Effects of the organic solvents on the conversion of alcohols
Reactant
Organic solvent
chlorobenzene dibutyl ether xylene benzene
Conversion, X, %
1-Butanol 83.22 58.94 49.65 55.48
1-Heptanol 81.44 50.16 41.94 44.90
1-Octanol 82.17 52.00 46.49 49.35
Cyclohexanol (2 h) 81.37 53.60 48.94 47.89
2-Ethoxyethanol (0.5 h) 92.82 87.86 79.61 73.86
2-(2-Ethoxyethoxy)-ethanol (0.5 h) 98.58 98.87 96.21 92.21
Dielectric constant 5.62 3.08 2.27 2.28
Data obtained from Wang and Chang; 145 9.17×10 -2 mol of alcohols, 10 mL of H 2O, 0.028 mol of CH 2Br 2,30gof
KOH,1gofTBAB catalyst, 50 mL of organic solvent, 1020 rpm, 50 o C
(B) Synthesis of ether compound catalyzed by crown ether (NPTC)
The other type of phase transfer catalyst is crown ether, cryptands, polyethylene glycol
(PEG) and their derivatives, and other nonionic phase-transfer agents. The phase transfer
agent complexes with inorganic cation, along with the anion, can be transferred to the
organic phase, preparing for reaction with organic-phase reactant. For example: with
18-crown-6 ether as a phase transfer agent for sodium cyanide:
[13.3.8]
The function of crown ether is that it can chelate with metal ion, such as: lithium, sodium
or potassium. Czech et al. 12 noted that crown ethers are a better phase-transfer catalyst
for solid-liquid reactions, whereas quaternary salts are better for a liquid-liquid system. Table
13.3.6 shows the solubilities of potassium salts in acetonitrile at 25 o C in the presence
and absence of 18-crown-6 ether. The solubility of potassium salts in CH 3CN highly depends
on the addition of 18-crown-6 ether.