Patent GB-387573-A (GB)
Title: Process for the esterification of organic acids with separation of the esters in highly concentrated form
IPC: F16L5/02
Filed: 1932-06-13
Abstract: The esterification of organic acids with alcohols is effected in two conjoint, consecutive working phases, the first of which is carried out in known manner in the presence of excess of alcohol, and in the second of which an excess of acid is present, causing practically complete esterification of the alcohol entrained in the vapour mixture from the excess alcohol phase, in which latter the acid not esterified in the excess acid phase is almost completely esterified, the ester passing out from the excess acid phase in highly concentrated form.  The alcohols to which the process may be applied are such that neither the boiling point of the alcohol nor of the ester attains 100 DEG  C., or, if an alcohol <PICT:0387573/IV/1> boiling above 100 DEG  C. such as butyl alcohol be employed, the boiling point of the binary or ternary mixtures formed must be below 100 DEG  C.  According to one example, methyl alcohol is passed from a container 12 through a tube 27 into a column 1, steam heating devices 14, 35, 36 being simultaneously turned on.  The alcohol vapours pass through tubes 28, 30 into the wash column 4 to which water at about 57-63 DEG  C. is led from a container 10 through a tube 23.  The aqueous alcohol solution is passed through a tube 31 into an alcohol evaporator 2 wherein the alcohol is again vaporized. When the requisite quantity of excess alcohol is circulating, 30-40 per cent acetic acid to which sulphuric acid has been added is supplied from a container 8, the supply of alcohol from the container 12 being also adjusted so that the excess is maintained.  The acid mixture passing out of the container 8 flows consecutively through the jacket of the cooler 6, the heat exchanger 13, the columns 3, 7, and reaches the upper part of the column 1 by a tube 34 at a temperature above the boiling point of the methyl acetate.  The ester together with the excess alcohol vapour leave through the tube 28. The dilute sulphuric acid passing to the evaporator 2 is here freed from alcohol, and leaves the system through a tube 32, the heat exchanger 13, and a tube 33.  The ester-alcohol vapours pass through the tube 18 into the wash column 4, the excess alcohol washed out therein passing back through the tube 31 into the evaporator 2, while the residual mixture passes through a tube 24 into the column 3 down which excess acid is flowing.  The mixture collecting at the bottom of this column passes through a tube 25 into the column 7, whence the alcohol is brought back through a tube 26 to the column 1, while the acid passes through the tube 34 into the upper part of the same column.  The methyl acetate vapours passing out through the tube 19 are washed in the column 5 with warm potassium acetate solution from the container 9, condensed in the cooler 6, and recovered at 16.  The sulphuric acid can also flow immediately from the container 11 into the column 1.  In other examples, the esterification with acetic acid of ethyl and butyl alcohol is described.  As wash liquid for the intermediate column, a suitable salt solution, for example, 10-15 per cent sodium sulphate, or the dilute acid itself may be employed.