Method for the sequestration of metal ions, and washing compositions

Alkaline washing compositions comprise an alkali cleanser (i.e an inorganic material which is alkaline in reaction and possesses cleansing properties) and an amino tri-(alkylidenephosphonic acid) of formula <FORM:1056177/C4-C5/1> wherein X and Y are the same or different and are H or C1-4 alkyl, or a water-soluble salt thereof. Specified alkaline agents are alkali metal and ammonium hydroxides and carbonates, preferably NaOH in a concentration of 1-20% of an aqueous composition. The preferred amino tri-(alkylidene phosphonic acid) is amino tri-(methylphosphonic acid) in the form of its penta-sodium salt (see Division C2). The phosphonic acid component of the compositions acts as a sequestering agent for metal cations (see Division C1). The compositions are used to wash bottles and glassware and may contain an anti-corrosive agent.ALSO:Amino tri(methylphosphonic acid) is prepared by condensing diethyl phosphite with ammonia and formaldehyde in aqueous medium to give hexaethyl amino tri(methylphosphonate) which is hydrolysed with conc. HCl; the pentasodium salt of the acid is prepared by reaction of the acid with aqueous NaOH.ALSO:Compositions containing an amino tri-(alkyldene-phosphonic acid) of formula <FORM:1056177/C1/1> wherein X and Y are H or C1- 4 alkyl or a water-solubl salt thereof are used to sequester heavy metal ions (e.g. Fe+ + +, Fe+ +, Co+ +, Mn+ +) in aqueous solutions.