Abstract: For the continuous preparation of 6-oxo-(6H)-dibenz-?c,e!?1,2!-oxaphosphorins (ODOPs), 6-chloro-(6H)-dibenz-?c,e!?1,2!-oxaphosphorins (CDOPs) are continuously reacted with at least the stochiometrically required amount of water at elevated temperature in a reaction section having little backmixing.

Abstract: The present invention relates to amphoteric water soluble polymers which containa) 90 to 30%-wt acrylic acid and/or methacrylic acidb) 10 to 60%-wt of a compound of the formula ##STR1## wherein R.sub.1 stands for hydrogen or the methyl radical, R.sub.2 and R.sub.3, which are the same or different, stand for the methyl or ethyl radical, and an optionally branched alkaline radical with 1 to 5 C atoms stands for Xand optionally, up to 50%-wt of acrylamidomethylpropane sulfonic acid and up to 10%-wt of a further ethylenically unsaturated compound, the molecular weight of these polymers, measured at a pH value of 8.0, being smaller than 100,000. The present invention also relates to the process for producing these polymers, and their use as grinding or dispersing agents for the production of highly concentrated aqueous pigment suspensions.