METHOD FOR PRODUCING C ETHERS OF 2,4-DICHLOROPHENOXYACETIC ACID Russian patent published in 2021 - IPC C07C69/65 C07C67/08 

FIELD: chemistry.

SUBSTANCE: invention relates to production of a herbicide - ester of C₈ 2,4-dichlorophenoxyacetic acid. Bottom residue of butyl alcohol distillation (TS 2421-101-05766575-2001) is a large-tonnage byproduct of production of butyl alcohols by oxosynthesis, constituting a transparent light yellow liquid with a density of 840 to 880 kg/m³, with distillation temperature range from 120 to 330°C and mass fraction of C₈ alcohols no more than 75%. Being a byproduct, BRBAD has a variable composition and constitutes a complex mixture of alcohols (predominantly C₈), ethers and esters, acetals and other impurities, wherein the content of 2-ethylhexanol in the mixture can reach 45%. Apart from 2-ethylhexanol, isooctenols are present in BRBAD in an amount of 8 to 30%. The alcohol fraction (AF) of the product for etherification with a total content of C₈ alcohols no less than 50 wt.% is isolated from BRBAD by fractional distillation at a vapour temperature of 150 to 190°C and atmospheric pressure or at a vapour temperature of 95 to 135°C and a pressure of 50 to 55 mm Hg. The isolated alcohol fraction (35 to 70% of the initial mass) contains predominantly 2-ethylhexanol (40 to 75%), 2-ethylhexenol isomers (10 to 35%), as well as a certain amount of C₄-C₇ alcohols, acetals, ethers and esters. The total content of alcohols in the fraction is determined by the GLC method. Etherification of 2,4-D with the alcohol fraction is executed as follows. 2,4-D and the alcohol fraction isolated from BRBAD (with a content of C₈ alcohols of at least 50%) are loaded into a container provided with a thermometer, a stirrer and a Dean-Stark apparatus with a reflux condenser, taking the molar ratio of 2,4-D and the alcohols (as calculated for 2-EH) as equal to 1:1.05÷1.5, respectively.

EFFECT: expanded range of sources of raw materials for producing 2,4-D alkyl esters, qualified disposal of industrial waste, reduced amount of reagents due to the elimination of a catalyst.

3 cl, 3 tbl, 3 ex