Patent GB-773022-A (GB)
Title: Improvements in and relating to 4-substituted 1:2-diaryl-3:5-dioxo-pyrazolidines
Filed: 1955-08-04
Abstract: The invention comprises 4-substituted 1:2-diaryl-3:5-dioxopyrazolidines of the general formula <FORM:0773022/IV(b)/1> (wherein Ar1 and Ar2 represent phenyl radicals which may be substituted by alkyl or alkoxy groups of up to 4 carbon atoms or by halogen, and R represents an aliphatic hydrocarbon radical with at least 12 carbon atoms) and their salts with inorganic or organic bases, and the preparation thereof by (a) condensing, preferably in the presence of an alkaline condensing agent, a substituted malonic acid diester of the general formula <FORM:0773022/IV(b)/2> (wherein X represents an alkyl radical of not more than 4 carbon atoms) with a hydrazobenzene derivative of the general formula <FORM:0773022/IV(b)/3> (wherein Z represents hydrogen or an acyl radical which can be easily split off), or (b) condensing, preferably in the presence of an acid binding agent, a substituted malonic acid derivative of the general formula <FORM:0773022/IV(b)/4> (wherein Y represents chlorine, bromine or an acyloxy group) with a hydrazobenzene of the general formula <FORM:0773022/IV(b)/5> or (c) first condensing, as in (b), a substituted malonic acid derivative of the general formula <FORM:0773022/IV(b)/6> with a hydrazobenzene derivative of the general formula V and then condensing the resulting substituted malonic acid monoester monohydrazide as in (a), or (d) condensing a 1:2-diaryl-3:5-dioxopyrazolidine of the general formula <FORM:0773022/IV(b)/7> with an aliphatic oxo compound R1 = O (wherein R1 represents a geminate bivalent radical having one hydrogen atom less than R) and simultaneously or later reacting with catalytically activated hydrogen, followed in each case, if desired, by conversion of the products into their salts with inorganic or organic bases. The products are useful as antipyretic, antiphlogistic and analgesic agents.  Examples describe the interaction of: (1) n-dodecylmalonic acid diethyl ester and hydrazobenzene in ethanol containing sodium ethoxide; the ester starting material may be replaced by the corresponding n-octadeca-9-enyl, n-octadecyl or n-pentadecyl compound; (2) n-dodecylmalonic acid dichloride and p:p1-dimethylhydrazobenzene in ether in the presence of dimethylaniline; the hydrazobenzene starting material may be replaced by p:p1-dichloro- or p:p1-dimethoxyhydrazobenzene; (3) n-dodecylmalonic acid monoethyl ester chloride and hydrazobenzene in benzene in the presence of pyridine, followed by heating of the resulting solution of n-dodecylmalonic acid monoethyl ester N:N1-diphenylhydrazide with a solution of sodium ethoxide in ethanol; (4) 1:2-diphenyl-3:5-dioxopyrazolidine with lauraldehyde and hydrogen in alcohol in the presence of platinized charcoal.  Additional starting materials are listed, including 4-ethoxy-41-bromohydrazobenzene.  Starting materials.  Substituted malonic esters of the general formula II are obtainable by condensation of sodium malonic acid diesters with aliphatic halogen compounds having at least 12 carbon atoms in the molecule, and may be converted to the corresponding acid halides by alkaline saponification, liberation of the acids and treatment thereof with inorganic acid halides such as SOCl2, PCl5 or PBr3.  Specification 646,597 is referred to.