Mesoxalyl urea 4-water ChDA
Mesoxalyl urea (mezoksalilomochevin) — is formed at action on uric acid of oxidizers in the presence of free strong acids.
Mesoxalyl urea is formed at introduction of uric acid in the small portions in the cooled concentrated nitric acid or at gradual addition of potassium chloride to mix of uric acid with salt.
In nitric acid mesoxalyl urea is insoluble and is emitted from liquid in process of education in the form of small crystals which after 24-hour standing separate from mother solution suction, are washed out by small amount of ice water and crystallize from hot aqueous solution; at dissolution temperature should not be higher than 70 ° as at more high temperature there comes decomposition.
From saturated warm aqueous solution mesoxalyl urea is emitted in big trekhklinomerny crystals with chetyremya water particles, easily disappearing on air; from hot solution odnoklinomerny prisms with one particle of the crystal water which is removed at temperature of 150 — 160 ° are allocated.
Reducers, for example stannous chloride, transfer mesoxalyl urea to C8H6N4O8 uroxin + 2H2O; so, this the last drops out in the form of crystal powder after addition of stannous chloride to the mesoxalyl urea solution prepared at effect of strong acid in the presence of potassium chloride; uroxin is transferred by oxidizers, e.g. the concentrated nitric acid, back to mesoxalyl urea.