Handbook of Solvents - George Wypych - ChemTech - Ventech!

806 Maw-Ling Wang
Table 13.3.3. Extraction of base by chlorobenzene solution of
tetra-n-octyl-ammonium bromide and alcohols (0.1 M) from an equal volume of 50%
NaOH (percent of the maximum possible basicity)
% %
Primary alcohols 2-tert-Butylcyclohexanol 2.0
Ethanol 4.5 3- Methylcyclohexanol 2.0
1-Propanol 5.0 tert-Alcohols
2-Methyl-1-propanol 4.4 tert-Butanol 0.3
1-Pentanol 4.3 2-Methyl-2-butanol 0.2
1- Hexanol 4.3 Diols
1-Heptanol 4.8 1,5-Pentanediol < 0.02
1-Octanol 2.0 2,5-Hexanediol 5.2
1-Dodecanol 0.8 2,2-dimethyl-1,3-propanediol 18.4
Secondary alcohols 2-Methyl-2,4-propanediol 28.0
2- Propanol 1.9 2,3-Dimethyl-2,3-butanediol 25.8
2-Pentanol 1.2 2,5-Dimethyl-2,5-hexanediol 32.0
2-Hexanol 1.1 Diol monoethers
2-Octanol 0.7 Ethylene glycol monoethylether 8.9
Cyclohexanol 0.5 Diethylene glycol monobutylether 8.7
4-tert-Butylcyclohexanol 1.5 Glycerol isopropylideneacetal 13.0
Data obtained from Dehmlow et al. 20
It is apparent that the order of decreasing alkoxide extraction with monohydric alcohols
is primary > secondary > tertiary. The better extractivity of diol anions can be attributed
to the relatively high acidity of these alcohols in part, but it seems that the main factors are
the distance between the two hydroxyl groups and the skeletal structure. In general, the concentration
of the extracted base depends on the amount of alcohol added. 20 The concentration
of aqueous sodium hydroxide is also an important factor in the extraction processes.
Herriott and Picker 36 carried out the reaction of thiophenoxide ion with
1-bromooctane in a two-phase system. They found that an increase in the ionic strength of
the aqueous phase or change to a more polar organic solvent increased the reaction rate. The
effect of organic solvent on the reaction rate under NPTC is given in Table 13.3.4. Correlations
between the rate constants and the partition coefficients indicate that the major function
of the catalyst is simply the solubilization of the nucleophilic in the organic phase.
Conventional methods of synthesizing ethers, i.e., Williamson synthesis and
alkoxymercuration have been well developed in organic chemistry. 76,96 The synthesis of
formaldehyde acetal were carried out from the reaction of alcohol and dichloromethane in a
50% sodium hydroxide solution applying Tixoget VP clay as a catalyst. However, completing
the reaction for such a low reaction rate takes long time. Dehmlow and Schmidt 15 first