| 摘要 |
<p>1520540 Vinyl acetate telomers and derivatives thereof PRODUITS CHIMIQUES UGINE KUHLMANN 16 Dec 1976 [19 Dec 1975] 52485/76 Heading C3P [Also in Division C2] Partial formals of vinyl acetate telomers of M.W. 500-5000 are prepared by (a) telomerizing vinyl acetate in the presence of a free-radical generator and a non-halogenated telogen, the molar ratio of telogen/vinyl acetate being 0À01- 4, (b) after possible distillation of unreacted vinyl acetate and/or telogen, partially reacting the telomer with formaldehyde in the presence of a strong mineral acid and in an organic solvent of formula CH3-R in which R is nitro, cyano or carboxyl, the molar ratio of formaldehyde to initial vinyl acetate being from 0À2-1, and (c) isolating the partial formal by precipitation in alkaline water. In Examples, vinyl acetate is telomerized in the presence of benzoyl peroxide and one of methyl ethyl ketone, 3- pentanone, 2,4-pentanedione, cyclohexanone, acetaldehyde, butyraldehyde or diethyl phosphite as telogen; the products are then reacted with formaldehyde in the presence of concentrated sulphuric acid and in some cases also hydrogen peroxide, in a solvent which is glacial acetic acid, nitromethane or acetonitrile; and the final products are partially neutralized with sodium hydroxide and isolated. Use.-Stabilizers for aqueous formaldehyde solutions.</p> |
