Sodium arsonoacetate

Sodium arsonoacetate is prepared by adding the freshly filtered and washed barium arsonoacetate as obtained above (without drying) to a solution of 108 g. of anhydrous sodium sulfate in 500 cc. of hot water. The mixture is mechanically stirred for one hour, the barium sulfate filtered off, and the filtrate concentrated on the steam bath until crystallisation commences. Upon cooling and stirring (Note 3), sodium arsonoacetate separates and is filtered by suction, the filtrate being concentrated to obtain a second crop of crystals. The yield of the combined fractions is 100-110 g. (80-88 per cent of the theoretical amount). 

A solution of 12.5 g. of sodium arsonoacetate and 30 g. of sodium hypophosphite (NallyPOa-HaO) in 150 cc. of cold 15 per cent sulfuric acid is allowed to stand at room temperature. After two or three days, the yellow precipitate is filtered off, washed with water, and dried in a vacuum over sulfuric acid or phosphorus pentoxide. A second crop is obtained by allowing the mother liquid to stand for two days longer. 

In view of the ease with which water attacks an ester of arsenate in water, we wondered if carbon nucleophiles would similarly attack a trialkyl arsenate to form a C—As bond. We (Sparkes and Dixon, unpublished work) therefore treated the sodium salt of diethyl malonate with tripropyl arsenate, and hydrolyzed during workup. Some arsonoacetic acid was formed, but we have not found conditions that give a useful yield. 

Arsonoacetic acid was obtained by Ehrlich and Bertheim 1 by treating -aminophenylarsenoacetic acid with bromine. It has been prepared by the action of three molecular equivalents of sodium chloroacetate on two of sodium arsenite, followed by isolation as the calcium salt,2 but it is found that these proportions are less satisfactory than the ones adopted.3 Arseno-acetic acid has been prepared recently by Palmer.3... 

Arsenic-76 labelled AMPA, 80, an analogue of methylenediphosphonate (MDP), and arsonoacetate (AAA), 81, an analogue of phosphonoacetate, have been synthesized by reacting [ As]arsenic trioxide (dissolved in sodium hydroxide) with chloromethyl phos-phinic acid ° or with monochloroacetic acid ° , respectively. 

Sodium salt monohydrate, C.HjAsNa.O, H.O, disodium arsonoacetate, disodium acetarsenate, acetarsonic acid disodi-um salt, sodium acetoarsinate, A ricyl. Crystals. Freely sol in water,... 

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