Patent GB-638279-A (GB)
Title: Improvements in or relating to fractionation of tall oil
IPC: C09F1/00
Filed: 1946-12-30
Abstract: Rosin acid concentrates are produced from tall oil by preferentially esterifying the fatty acids in tall oil with an open chain alcohol containing 1 to 5 carbon atoms and consisting of carbon, hydrogen and oxygen, then contacting the ester mixture simultaneously with naphtha and a polar solvent immiscible with naphtha (e.g. wet furfural) to obtain two liquid phases, one comprising naphtha containing in solution a concentrate of the fatty acid esters and a minor proportion of rosin acids, the other phase comprising the polar solvent containing in solution a p  concentrate of rosin acids containing a minor amount of fatty acid esters, separating the solutions and recovering the solvents. The naphtha is a liquid hydrocarbon or mixture of hydrocarbons which is immiscible with furfural or other polar solvent being used, is sufficiently volatile to be separable from the fatty acid esters by distillation (e.g. boiling within the range 30-220 DEG  C.) and is preferably composed of paraffin hydrocarbons.  The ester mixture may be dissolved in a portion of the naphtha before being contacted with the polar solvent and the remainder of the naphtha. The polar solvent may be furfural or a furfural-water mixture containing about 1 to 15 per cent of water.  A distillate rosin acid fraction may be obtained from the rosin acid concentrate by fractional distillation, particularly under reduced pressure. The alcohol used for the preferential esterification of the tall oil fatty acids may be methyl, ethyl, propyl, isopropyl, n-butyl or secondary butyl alcohol; ethylene, diethylene, 1-2 or 1-3 propylene glycol, glycerol or pentaerythritol. In an example, 110 parts by volume of crude tall oil, 22 of methyl alcohol and 1-9 of concentrated sulphuric acid are heated under a reflux for 2.5 hours, allowed to separate into two layers, the upper layer dissolved in 70 parts by volume of light petroleum naphtha and washed with water.  50 parts by volume of the solution are pumped into the middle of a conventional countercurrent vertical solvent extraction column and intimately contacted with 212 parts by volume of furfural saturated with water and naphtha at 80 DEG  F. introduced at the top of the column.  It is also intimately contacted with 78 parts by volume of naphtha introduced at the bottom of the column. The temperature of the column is maintained at 85-86 DEG  F.  The extract and raffinate discharged from the bottom and top of the column respectively are freed from solvent by distillation under reduced pressure.  The raffinate, or naphtha soluble portion is further distilled to yield a fatty acids methyl esters distillate and a residue rich in sterols.  The extract having a rosin acid content of 84.7 per cent calculated as abietic acid is fractionally distilled to yield a forerun of 15.5 per cent, 69.5 per cent of a hard rosin distillate fraction and a residue.  A long list of polar solvents which may be used is given and it is stated that many of these may be used wholly or partially saturated with water.  Data are given for the percentages of rosin acid in the raffinate and extract respectively obtained when partially methylated tall oil is extracted in one stage at 77 DEG  F. with a naphtha and a series of polar solvents in various proportions.ALSO:Rosin acid concentrates are produced from tall oil by preferentially esterifying the fatty acids in tall oil with an open chain alcohol containing 1-5 carbon atoms and consisting of carbon, hydrogen and oxygen, then contacting the ester mixture simultaneously with naphtha and a polar solvent immiscible with naphtha to obtain two liquid phases, one comprising naphtha containing in solution a concentrate of the fatty acid esters and a minor proportion of rosin acids, the other phase comprising the polar solvent containing in solution a concentrate of rosin acids containing a minor proportion of fatty acid esters, separating the solutions and recovering the solvents.  The naphtha is a liquid hydrocarbon or mixture of hydrocarbons which is immiscible with furfural or other polar solvent being used, boils below 250-300 DEG C., e.g. boils within the range 30-220 DEG  C., and is preferably composed of paraffin hydrocarbons.  The ester mixture may be dissolved in a portion of the naphtha before being contacted with the polar solvent and the remainder of the naphtha. The polar solvent may be furfural or a furfural-water mixture containing about 1-15 per cent of water.  A distillate rosin and fraction may be obtained from the rosin acid concentrate by fractional distillation, particularly under reduced pressure. The alcohol used for the preferential esterification of the tall oil fatty acids may be methyl, ethyl, propyl, isopropyl, n-butyl or secondary butyl alcohol; ethylene, diethylene, 1-2 or 1-3 propylene glycol, glycerol or pentaerythritol. In an example, 110 parts by volume of crude tall oil, 22 of methyl alcohol and 1.9 of concentrated sulphuric acid are heated under a reflux for 2.5 hours, allowed to separate into two layers, the upper layer dissolved in 70 parts by volume of light petroleum naphtha and washed with water.  50 parts by volume of the solution are pumped into the middle of a conventional countercurrent vertical solvent extraction column and intimately contacted with 212 parts by volume of furfural saturated with water and naphtha at 80 DEG  F. introduced at the top of the column.  It is also intimately contacted with 78 parts by volume of naphtha introduced at the bottom of the column. The temperature of the column is maintained at 85-86 DEG  F.  The extract and raffinate discharged from the bottom and top of the column respectively are freed from solvent by distillation under reduced pressure.  The raffinate or naphtha soluble portion is further distilled to yield a fatty acids methyl esters distillate and a residue rich in sterols.  The extract having a rosin acid content of 84.7 per cent calculated as abietic acid is fractionally distilled to yield a forerun of 15.5 per cent 69.5 per cent of a hard rosin distillate fraction and a residue. A long list of polar solvents which may be used is given and it is stated that many of these may be used wholly or partially saturated with water.  Data are given for the percentages of rosin acid in the raffinate and extract respectively, obtained when partially methylates tall oil is extracted once at 77 DEG  F. with a naphtha and a series of polar solvents in various proportions.