| 摘要 |
<p>Halohydrins having up to 4 carbon atoms per molecule are extracted from aqueous solution by contacting with a water insoluble carboxylic acid or anhydride having at least 4 carbon atoms per molecule, to form a solution of the halohydrin therein, and separating the acid from the aqueous phase. The acid employed may be preferably a mono-carboxylic acid of molecular weight of at least 116, or an aliphatic carboxylic acid, or may be a C4 to C20 acid, optionally halogen substituted, being less than 2% by weight at 20 DEG C. or preferably less than 0.5% at 20 DEG C. water soluble and includes linoleic, ricinoleic acids, or mixtures of acids obtained by the hydrolysis of naturally occurring glycerides, or tall oil or tall oil fatty acids. A list of acids which includes specific representatives is given. The acid has preferably an atmospheric boiling point 20 DEG C. higher or lower than the halohydrin. The aqueous solution may in addition to the halohydrin contain hydrochloric acid, halides or sulphates of alkali or alkaline earth metals. The process may be effected in a continuous countercurrent mode, the carboxylic acid containing the halohydrin being separated and recovered from the halohydrin for reuse by distillation or by steam distillation. The apparatus which may be used for the continuous process can be a tower, to which the extractant is fed in at the base and aqueous halohydrin near the top. The examples illustrate batchwise and continuous processes of glycerol dichlorohydrin recovery and show the effect of salt concentration on partition co-efficients. The invention may be employed for recovering ethylene chlorohydrin, bromohydrin, iodohydrin, 1-ry and 2-ry propylene chlorohydrin, bromohydrin, iodohydrin; other halohydrins are specified. The extraction is carried out at a temperature at which the acid is a liquid, e.g. 70-71 DEG C. using stearic; higher temperatures may also be employed if necessary by effecting the contact of the phases under pressure in excess of atmospheric.</p> |
