Patent GB-723244-A (GB)
Title: Improvements in or relating to surface-active agents
IPC: C11C3/00
Filed: 1952-04-02
Abstract: Surface-active compounds are prepared by reacting a previously intermolecularly esterified substantially non-polymerized aliphatic hydroxy carboxylic acid, said acid containing before intermolecular esterification at least 8 carbon atoms, with a previously formed polycondensate of an aliphatic polyvalent alcohol containing at least 3 carbon atoms and at least 3 hydroxyl groups, the reactants being in such proportions as to form a partial ester-ether.  The reaction is generally carried out at between 180 DEG  C. and 230 DEG  C. in the presence of an esterification catalyst for such a time that the product has an acid value of not more than 10.  The hydroxy carboxylic acids are converted into the estolide reactant by heating, generally at between 200 DEG  C. and 230 DEG  C., under reduced pressure; an inert gas such as nitrogen or carbon dioxide may be passed through the heated mass; the condensation is preferably continued until the polycondensed acid has an acid value of between 25 and 70.  The hydroxy acids may be saturated or unsaturated and contain as many as six hydroxyl groups; the preferred acids contain between 12 and 20 carbon atoms, e.g. ricinoleic acid, mono- and dihydroxystearic acids, castor oil mixed fatty acids and the dihydroxy acid obtained from palmitoleic acid, the tetrahydroxy acid from linoleic acid and the hexahydroxy acid from linolenic or eleostearic acid by oxidation. The polyvalent alcohols preferably contain 3 to 6 carbon atoms and include glycerol, erythritol, penta erythritol and mannitol.  A suitable condensate approximating to the trimer is obtained by heating glycerol under a vacuum to between 220 DEG  C. and 250 DEG  C. in presence of aqueous NaOH as catalyst.  The partial ester-ethers may be used as emulsifying and/or stabilizing agents for water-in-oil emulsions (see Groups I and III) and are useful in the manufacture of chocolate and chocolate coated ice cream (see Group VI).  In examples, (1) castor oil fatty acids are polycondensed and the resulting estolide of acid value 35 is reacted with a polyglycerol; (3) mono-hydroxy stearic acid obtained by splitting hydrogenated castor oil is polycondensed to an acid value of 36.3 and then esterified with polyglycerol; (5) di-hydroxy stearic acid obtained by alkaline permanganate oxidation of crude tea-seed oil is polycondensed to an acid value of 31 and then esterified with a polyglycerol; a partially esterified polyglycerol of acid value about 2 results in each case.ALSO:Water-in-oil emulsions comprise, as emulsifying agent, a partial ester-ether prepared by reacting a previously intermolecularly esterified substantially non-polymerized aliphatic hydroxy carboxylic acid, the acid containing at least 8 carbon atoms before the esterification, with a previously formed polycondensate of an aliphatic polyvalent alcohol containing at least 3 carbon atoms and at least 3 hydroxyl groups (see Group IV(b)).  In Examples: (1) a water-in-oil emulsion is formed from sunflower oil using a partial polyglycerol ester of a ricinoleic acid estolide, a monohydroxy stearic acid estolide or a di-hydroxy stearic acid estolide; (2) a grease for baking-plates is made from a fatty oil and the first-mentioned partial ester-ether of (1).  Partial ester-ethers of poly-erythritol, poly-pentacrythriol and polymannitols are also mentioned.ALSO:Ointments, hair dressings and face-creams, and also chocolate may comprise as the emulsifying agent a partial ester-ether prepared by reacting a previously intermolecularly esterified substantially non-polymerised aliphatic hydroxy carboxylic acid, which acid before intermolecular esterification contains at least 8 carbon atoms, with a previously formed poly condensate of an aliphatic polyvalent alcohol containing at least 3 hydroxyl groups, the reactants being in such proportions as to form a partial ester ether (see Group IV (b)).  In the case of chocolate, the additive serves to reduce the viscosity and prevent thickening when the chocolate is used in coating frozen confectionory e.g., ice cream. Examples are given of chocolate couvertures containing cocoa butter, sugar and cocoa solids wherein a partial polyglyerol ester of ricinoleic acid estolide is used as an emulsifying agent and the viscosity and anti-thickening actions of the ester-ether are compared with those achieved by means of lecithin.