Patent GB-695702-A (GB)
Title: Improved tall oil treatment
IPC: C11B13/00
Filed: 1949-06-29
Abstract: An alkali metal soap of tall oil is heated with an amount of alkali metal hydroxide at least equal to the amount of the combined alkali metal in the soap (calculated as alkali metal hydroxide) to a temperature of 230 DEG  to 300 DEG  C. for at least four hours to effect isomerization and subsequent degradation of the unsaturated fatty acids into saturated fatty acids of a lower carbon content and to convert the rosin fraction present in the original tall oil into a more stable form by reducing its degree of unsaturation.  Acetic acid (in the form of its salt) and hydrogen are formed as by-products. The saturated fatty acids formed are mainly palmitic and myristic acids.  A hydrogenation catalyst may also be added to the reaction mass and the hydrogen evolved may be utilized directly for hydrogenating the unsaturated fatty acids and rosin.  The product will then consist of a mixture of palmitic, myristic and stearic acids and partly hydrogenated rosin.  The process may be carried out batchwise or in a continuous manner.  The free fatty acids may be liberated from the soap product by acidifying with a strong acid such as sulphuric or hydrochloric acid and may then be separated from the stabilized rosin by fractional distillation under reduced pressure or by dissolving the acidified product in a solvent from which the fatty acids precipitate out but which retains the rosin in solution. Specified solvents are petroleum hydrocarbons, e.g. gasoline, kerosine or heptane; aromatic hydrocarbons, e.g. benzene, toluene and xylene; alcohols such as methyl, ethyl, or isopropyl alcohol, ketones such as acetone, ethyl methyl ketone or cyclohexanone; and chlorinated hydrocarbons, e.g. ethylene dichloride or trichlorethylene.  In examples: (1) the neutral potassium soap of tall oil is mixed with a strong aqueous solution of potassium hydroxide and the mixture heated to boil off all the water.  The mixture is then further heated at 230 DEG  to 290 DEG  C. for six hours and the product cooled, dissolved in water and the soap salted out by adding sodium chloride; (2) the crude soap mixture product obtained in (1) is dissolved in water and then acidified with strong hydrochloric acid to yield myristic and palmitic acids and stabilized rosin; (3) the mixture of fatty acids and stabilized rosin obtained in (2) is fractionally distilled to yield an acid fraction comprising mainly palmitic and myristic acids, the still residue being a stabilized rosin fraction; (4) crude tall oil is saponified with sodium hydroxide solution and the soap then heated for five hours with additional sodium hydroxide in a steel autoclave at 230 DEG  to 290 DEG  C. and 12 to 14 atmospheres pressure; the product is then cooled, dissolved in water, and the solution acidified with sulphuric acid to yield a fatty layer which is dissolved in acetone, the fatty acids being precipitated by cooling the solution to -20 DEG  C. and the stabilized rosin recovered from the mother liquor by distilling off the acetone; (5) crude "sulphate soap" is heated with sodium hydroxide solution at 280 DEG  C. for six hours and the product cooled, dissolved in hot water and acidified with sulphuric acid to liberate the fatty acids and stabilized rosin which may be converted into its sodium soap.  In a comparative example commercial abietic acid is heated in an autoclave with sodium hydroxide solution at 260 DEG  C. for five hours and the product dissolved in hot water and acidified with sulphuric acid to yield a product of lower acid number and lower iodine number.ALSO:An alkali metal soap of tall oil is heated with an amount of alkali metal hydroxide at least equal to the amount of the combined alkali metal in the soap (calculated as alkali metal hydroxide) to a temperature of 230 DEG  to 300 DEG C for at least four hours to effect isomerization and subsequent degradation of the unsaturated fatty acids into saturated fatty acids of a lower carbon content and to convert the rosin fraction present in the original tall oil into a more stable form by reducing its degree of unsaturation.  Acetic acid (in the form of its salt) and hydrogen are formed as by-products.  The saturated fatty acids formed are mainly palmitic and myristic acids.  A hydrogenation catalyst may also be added to the reaction mass and the hydrogen evolved may be utilized directly for hydrogenating the unsaturated fatty acids and rosin. The product will then consist of a mixture of palmitic, myristic and stearic acids and partly hydrogenated rosin.  The process may be carried out batchwise or in a continuous manner.  The free fatty acids may be liberated from the soap product by acidifying with a strong acid such as sulphuric or hydrochloric acid and may then be separated from the stabilized rosin by fractional distillation under reduced pressure or by dissolving the acidified product in a solvent from which the fatty acids precipitate out but which retains the rosin in solution. Specified solvents are petroleum hydrocarbons, e.g. gasoline, kerosine or heptane; aromatic hydrocarbons, e.g. benzene, toluene or xylene, alcohols such as methyl, ethyl or isopropyl alcohol, ketones such as acetone, ethyl methyl ketone or cyclohexanone, and chlorinated hydrocarbons, e.g. ethylene dichloride or trichlorethylene.  In examples: (1) the neutral potassium soap of tall oil is mixed with a strong aqueous solution of potassium hydroxide and the mixture heated to boil off all the water.  The mixture is then further heated at 230 DEG  to 290 DEG C for six hours and the product is cooled, dissolved in water and the soap salted out by adding sodium chloride; (2) the crude soap mixture obtained in (1) is dissolved in water and then acidified with strong hydrochloric acid to yield myristic and palmitic acids and stabilized rosin; (3) the mixture of fatty acids and stabilized rosin obtained in (2) is fractionally distilled to yield an acid fraction comprising mainly palmitic and myristic acids, the still residue being stabilized rosin fraction; (4) crude tall oil is saponified with sodium hydroxide solution and the soap then heated for five hours with additional sodium hydroxide in a steel autoclave at 230 DEG  to 290 DEG C and 12 to 14 atmospheres pressure; the product is then cooled, dissolved in water, and the solution acidified with sulphuric acid to yield a fatty layer which is dissolved in acetone, the fatty acids being precipitated by cooling the solution to -20 DEG C and the stabilized rosin recovered from the mother liquor by distilling off the acetone; (5) crude "sulphate soap" is heated with sodium hydroxide solution at 280 DEG C for six hours and the product cooled, dissolved in hot water and acidified with sulphuric acid to liberate the fatty acids and stabilized rosin, which may be converted into its sodium soap. In a comparative example commercial abietic acid is heated in an autoclave with sodium hydroxide solution at 260 DEG C for five hours and the product dissolved in hot water and acidified with sulphuric acid to yield a product of lower acid number and lower iodine number.