Patent GB-733798-A (GB)
Title: Improvements in or relating to herbicides
IPC: A01C3/02
Filed: 1952-10-15
Abstract: The invention comprises an ester of 2-(2 : 4-dichlorophenoxy) ethanol with a mono- or poly-carboxylic acid containing from 1 to 18 carbon atoms in which the acid is an aliphatic saturated acid or an aliphatic saturated acid having chloro, hydroxy or chloro-phenoxy substituents, or a carbocyclic acid or a carbocyclic acid having chloro- or alkyl substituents.  In esters of polycarboxylic acids all the carboxylic groups may be esterified with the 2-(2 : 4-dichlorophenoxy) ethanol, or a carboxylic group may remain unesterified or be neutralized with an alkali metal or an alkaline earth metal or with an ammonium group or an amine group such as morpholine or a methanol- or ethanolamine.  The esters can be prepared by ester interchange or by reaction of 2-(2 : 4-dichlorophenoxy) ethanol with the appropriate acid or anhydride, suitably with azeotropic distillation of any water liberated.  In example (A) 2-(2 : 4-dichlorophenoxy) ethyl benzoate is prepared by heating a mixture of 2-(2 : 4-dichlorophenoxy) ethanol, benzoic acid, xylene and a sulphuric acid catalyst with distillation of water from the mixture.  Similarly prepared from the corresponding acids or anhydrides in suitable proportions are the oxalic acid di-ester, butyrate, acetate, chloracetate, naphthenate (from caroxylic acids containing five-carbon-ring structures with side chains, recovered from petroleum), malic acid di-ester, tartaric acid di-ester, 2-ethyl hexanoate, succinate (di-ester), 2,4-dichlorophenoxy-acetate, formate, p-chlorobenzoate, phthalate (di-ester), and the acid succinate of the ethanol derivative.  The mono-esters of polycarboxylic acids are converted to the salts, e.g. by reaction with sodium hydroxide.  There are prepared in this manner the sodium salts of the oxalic, succinic and glutaric acid monoesters.  The products are useful as herbicides (see Group VI)ALSO:As an active ingredient of herbicidal compositions there is employed an ester of 2-(2 : 4-dichlorophenoxy)ethanol with a mono- or polycarboxylic acid containing from 1 to 18 carbon atoms, in which the acid is an aliphatic saturated acid or an aliphatic saturated acid having chloro, hydroxy, or chlorophenoxy substituents or a carbocyclic acid or a carbocyclic acid having chloro or alkyl substituents.  The esters may be applied in dusts or powders with such extenders as talc or infusorial earth, or in aqueous sprays which preferably contain a suspending or wetting agent such as alkyl aryl polyoxyalkylene glycols or alkyl aryl polyether alcohols.  They may be packed as concentrates with dispersing agents and, where necessary, organic solvents. Powdered concentrates which have been impregnated using an ester in a solvent may be used.  The compositions may also contain fungicides and insecticides of the contact, poison and repellent types, e.g. nicotine sulphate, pyrethrum, allethrin, arsenates or DDT.  The preparation is described (see Group IV (b)) of the benzoate, oxalic acid di-ester, butyrate, acetate, chloracetate, naphthenate, malic acid di - ester, tartaric acid di - ester, 2 - ethylhexanoate, succinate (di-ester), 2,4-dichlorophenoxy - acetate, formate, p - chlorobenzoate, phthalate (di-ester) and acid succinate of the 2-(2,4 - dichlorophenoxy)ethanol, of the monoesters of oxalic, succinic and glutaric acids with that of ehhanol and of the corresponding sodium salts.