Formaldehyde → N-(Carboxymethyl)-N-(phosphonomethyl)glycine

Participants

Reaction Conditions

Reaction Steps

Concentrated filtrates from Cycle 1 were charged to a 500 ml three neck flask fitted with thermometer, condenser, dropping funnel and stirrer. Phosphorous acid (40.8 g, 0.493 moles), iminodiacetic acid (63.6 g, 0.469 moles) and sulphuric acid (5.0 g, 0.050 moles) were added, with stirrring, to the flask (sulphuric acid was charged on the assumption that 10% of the sulphuric acid was lost in the wash and filter cake). The reaction mixture was then heated to 120° C. and formaldehyde (46.1 g at 36.1% strength, 0.555 moles) was then added over one hour. The temperature was maintained between 110° and 120° C. during addition. On complete addition the reaction mixture was allowed to cool to 25° C. over 90 minutes. The reaction mixture was filtered and the filter cake washed with water (57 ml). The product was dried in a vacuum oven to yield 102.2 g of N-phosphonomethyliminodiacetic acid at 95.4% strength equivalent to a cumulative isolated yield of 75.3%. The filtrates (99.3 g) and the water wash (76.8 g) were analysed at 7.5% and 3.7% N-phosphonomethyliminodiacetic acid respectively. This was equivalent to a total cumulative conversion yield of 81.7% N-phosphonomethyliminodiacetic acid.

Provenance & Evidence