Patent GB-791165-A (GB)
Title: Interesterification of fatty acid esters
IPC: C11C3/10
Filed: 1954-10-08
Abstract: The interesterification of a mixture of substantially completely esterified fatty acid esters to re-arrange the fatty acid radicals in the mixture is effected by heating the mixture to at least 180 DEG C. in the presence of a plural metal soap catalyst comprising a soap or soaps of at least two metals, one of the metals being an alkali or alkaline earth metal and the other being an amphoteric metal and said soap or soaps being derived from one or more fatty acids having at least 5 carbon atoms per molecule. The fatty acid esters may be esters of either polyhydric alcohols such as glycerol; glycols such as ethylene glycol, propylene glycol, and polyalkylene glycols; cellulose, sorbitol, mannitol, or pentaerythritol, or of monohydric alcohols, e.g. methanol, ethanol, propanol, or butanol.  The fatty acid radicals in the esters may be saturated or unsaturated, thus the esters may be acetates, propionates, butyrates, valerates, caproates, caprylates, caprates, laurates, myristates, palmitates, stearates, arachidates, behenates, carnaubates, cerotates, montanates, oleates, sorbates, linoleates, linolinates and elaidates.  In the case of esters of polyhydric alcohols the alcohol may be esterified with the same or different fatty acids. The plural metal soap catalyst may be added to the ester mixture in the form of a double metal soap or in the form of soaps of the individual metals, or in the form of separate alkali or alkaline earth metal compounds and amphoteric metal compounds capable of reacting in the reaction mixture to form the soaps of the two metals.  Alternatively, one of the metal compounds can be in the form of a metal soap and the other metal compound in a form capable of supplying the metal ions necessary to form the metal soap catalyst.  The alkali or alkaline earth metal in the catalyst may be sodium, potassium, lithium, caesium, calcium, strontium, or barium while the amphoteric metal may be aluminium, titanium, zirconium, cerium, tin, lead, cobalt, molybdenum, manganese, cadmium, iron, copper, chromium, vanadium, thallium, nickel, platinum, palladium or zinc.  It is preferred to use aluminium- or titanium-containing soaps.  Suitable double metal soaps which can either be formed in situ or added as a preformed double metal soap include lithium aluminium stearate (or palmitate), sodium aluminium oleate, sodium titanium stearate, lithium (or potassium) titanium palmitate, potassium aluminium myristate, lithium zirconium linoleate, calcium (or barium) aluminium stearate, calcium (or strontium) titanium palmitate, sodium zirconium stearate, lithium cerium oleate, sodium cobalt stearate, lithium zinc myristate, sodium cadmium linoleate, lithium lead stearate, and potassium copper stearate.  The soap may be formed in situ by adding the metals in the form of an alcoholate, e.g. the methoxide, ethoxide, or isopropoxide, or in the form of an oxide, chloride or hydroxide of the metal.  When the catalyst is formed in the reaction mixture it is desirable to add the metal-containing components in a mol. for mol. ratio. The catalysts are preferably employed in a concentration of about 0.01 mols. per kilogram of charge.  The interesterification is preferably effected at 230 DEG  to 260 DEG  C., the catalyst being inactive at temperatures below 180 DEG  C. and usually below 200 DEG  C. The process is particularly useful for modifying the characteristics of triglyceride fats and fatty oils such as lard, butter, butter oil, tallow, cocoa butter, unhydrogenated or partially or fully hydrogenated vegetable oils such as soybean oil, peanut oil, coconut oil, cottonseed oil, and corn oil, or of mixtures of these or other fats and fatty oils.  Fatty acid full esters of polyhydric alcohols wherein the alcohol is esterified with both higher and lower fatty acids may be prepared by reacting a lower fatty acid ester, e.g. triacetin or tributyrin with a C6 to C24 or higher fatty acid ester, e.g. tripalmitin, triolein, tristearin, oleodipalmitin, stearodilaurin or palmitodistearin.  Triglycerides can also be cross esterified with fully esterified glycols whilst low melting or liquid fats can be interesterified with a pure triglyceride such as tristearin.  The mixtures treated need not be anhydrous or acid-free and when the catalyst is formed in situ the presence of free fatty acid in the mixture is desirable.  The reaction can be terminated by cooling the mixture below 180 DEG  C. or more usually below 200 DEG C. to inactivate the catalyst and then separating the products, e.g. by vacuum distillation, solvent extraction, or fractional crystallization.  Examples are given for the interesterification of hydrogenated lard with triacetin, using the following as catalysts or as the catalyst-forming materials: (1) lithium aluminium ethylate (prepared by adding an ethereal solution of lithium aluminium hydride to ethanol); (2) aluminium isopropoxide and lithium isopropoxide; (3) lithium stearate and aluminium stearate; (4) sodium methoxide and aluminium stearate; (5) strontium hydroxide and aluminium stearate; (6) calcium hydroxide and aluminium stearate; (7) sodium hydroxide and zinc palmitate; (8) lithium stearate and cobalt stearate; (9) strontium hydroxide and aluminium stearate; (10) sodium hydroxide and titanium ethylate; (11) lithium stearate and titanium ethylate; (12) lithium stearate and manganese stearate; (13) lithium stearate and tin acetate; (14) a lithium vanadium soap catalyst; and (15) lithium stearate and chromium stearate.  The product from the preceding examples generally comprises diacetomonostearin and diacetomonopalmitin, with small amounts of acetomyristates and acetoarachidates.  Other examples are given for the interesterification of (16) lard with triacetin in the presence of sodium hydroxide and aluminium isopropoxide, and for the interesterification of the following in the presence of lithium and aluminium stearates; (17) unbleached lard; (18) cottonseed oil; (19) soybean oil; (20) menhaden oil; (21) hydrogenated lard and tributyrin; (22) hydrogenated coconut oil and triacetin; (23) unhydrogenated lard and tributyrin; (24) coconut oil and ethyl stearate; (25) coconut oil and methyl palmitate; (26) pentaerythritol tetraoleate and triacetin; (27) cottonseed oil and hydrogenated lard, and (28) distilled coconut oil.  A comparative example is given to show that attempts to interesterify hydrogenated lard and triacetin using lithium stearate alone and aluminium stearate alone as catalyst were unsuccessful.ALSO:The interesterification of a mixture of substantially completely esterified fatty acid esters to rearrange the fatty acid radicals in the mixture is effected by heating the mixture to at least 180 DEG  C. in the presence of a plural metal soap catalyst comprising a soap or soaps of at least two metals, one of the metals being an alkali or alkaline earth metal and the other being an amphoteric metal and said soap or soaps being derived from one or more fatty acids having at least 5 carbon atoms per molecule. The fatty acid esters may be esters of glycerol and the fatty acid radicals in the esters may be saturated or unsaturated; thus the esters may be caproates, caprylates, caprates, laurates, myristates, palmitates, stearates, arachidates, behenates, carnaubates, cerotates, montanates, oleates, sorbates, linoleates, linolinates and elaidates.  The plural metal soap catalyst may be added to the ester mixture in the form of a double metal soap or in the form of soaps of the individual metals, or in the form of separate alkali or alkaline earth metal compounds and amphoteric metal compounds capable of reacting in the reaction mixture to form the soaps of the two metals. Alternatively, one of the metal compounds can be in the form of a metal soap and the other metal compound in a form capable of supplying the metal ions necessary to form the metal soap catalyst. The alkali or alkaline earth metal in the catalyst may be sodium, potassium, lithium, caesium, calcium, strontium or barium while the amphoteric metal may be aluminium, titanium, zirconium, cerium, tin, lead, cobalt, molybdenum, manganese, cadmium, iron, copper, chromium, vanadium, thallium, nickel, platinum, palladium or zinc.  It is preferred to use aluminium- or titanium-containing soaps.  Suitable double metal soaps, which can either be formed in situ or added as a preformed double metal soap, include lithium aluminium stearate (or -palmitate), sodium aluminium oleate, sodium titanium stearate, lithium (or potassium) titanium palmitate, potassium aluminium myristate, lithium zirconium linoleate, calcium (or barium) aluminium stearate, calcium (or strontium) titanium palmitate, sodium zirconium stearate, lithium cerium oleate, sodium cobalt stearate, lithium zinc myristate, sodium cadmium linoleate, lithium lead stearate and potassium copper stearate. The soap may be formed in situ by adding the metals in the form of an alcoholate, e.g. the methoxide, ethoxide, or isopropoxide, or in the form of an oxide, chloride or hydroxide of the metal.  When the catalyst is formed in the reaction mixture it is desirable to add the metal-containing components in a mole. for mole. ratio. The catalysts are preferably employed in a concentration of about 0.01 moles. per kilogram of charge.  The interesterification is preferably effected at 230-260 DEG  C., the catalyst being inactive at temperatures below 180 DEG  C. and usually below 200 DEG  C.  The process is particularly useful for modifying the characteristics of triglyceride fats and fatty oils such as lard, butter, butter oil, tallow, cocoa butter, unhydrogenated or partially or fully hydrogenated vegetable oils such as soybean oil, peanut oil, coconut oil, cottonseed oil, and corn oil, or of mixtures of these or other fats and fatty oils.  Fatty acid full esters of glycerol wherein the glycerol is esterified with both higher and lower fatt