Defoaming and surface active compositions

Polymers of molecular weight 3800-4700 and having the general formula are used as surface active and defoaming agents in quantities of 1-10% by wt. in detergents containing caustic materials, e.g. sodium hydroxide.ALSO:The invention comprises compounds of general formula wherein X is an integer such that the number of oxypropylene groups defined thereby constitutes 27 to 33 per cent by weight of the compounds (y x y1) is an integer such that the number of oxyethylene groups defined thereby constitutes 31 to 41% by weight of the compounds and (z + z1) is an integer such that the number of oxypropylene groups defined thereby constitutes 27 to 36% by weight of the compounds, the average molecular weight of the compounds being 3800 to 4700. They are prepared by reacting the correconding hydroxyl-ended polymer with two mole equivalents of metallic sodium at 80 DEG to 146 DEG C. for 2 to 24 hours to form the sodium alcoholate which is reacted with two mole equivalents of benzyl bromide or chloride for 45 minutes to 3 hours at 100 DEG to 145 DEG C.