N,N-dimethylacrylamide with most solvents (e. g..water, alcohols, benzene, light petroleum) a bead polymer ( 7) is only accessible in this way. (7) To a suspension of polymer (6) (12.1 g) in acetone (350ml) and glacial acetic acid (600mg) in a glass autoclave cooled to 0°C is added anhydrous dimethylamine (l00ml). The mixture was shaken for 30min at room temperature and 24h at 50°C; after washing with acetone, ether, acetone, pyridine, ethanol, acetone, and ether the polymer was dried in uucuo at 50°C. Elemental analysis (N 4.9%) shows the polymer to contain 34.7 mol % of amide groups. (7) possesses excellent solvation properties. The degree of swelling is 12 in pyridine, 15 in dimethyl sulfoxide, 10 in dimethylformamide, 5 in water, 5 in ethanol, and 12 in water/methanol (1 : 1, v/v).
Polymeric carboxumide
It is also possible to react the activated ester groups in (6) first with a limiting amount of a nucleophile (primary reactant) and subsequently with another nucleophile (secondary reactant). In this way the amount of primary reactant to be introduced and the solvation (swelling) properties of its environment can be varied within wide limits. In (7) part of the N,N-dimethylamide groups obtained on reaction with an excess of dimethylamine can be hydrolyzed to carboxyl groups. A polymer of this kind is used in the solid phase synthesis of oligonucleotide^[^!