GB1030745A - Aldehyde polymerisation process - Google Patents

Abstract

A polymeric aldehyde is prepared by polymerizing at least one aldehyde in the presence of a polymerization initiator at a temperature below that at which the initiator would also act as catalyst for the degradation of the polymer so formed and the initiator is thereafter rendered ineffective as a catalyst for such degradation, the initiator being a compound having an alkali metal, alkaline earth metal, boron, aluminium, germanium, tin or lead atom directly linked to a monovalent group of the structure: -O-CmH2m-NR2, where m is a positive integer and R is a monovalent hydrocarbon radical or hydrogen. The polymerization may be effected in the presence of acid contamination provided the amount of acid present does not substantially exceed 3 moles per mole of initiator. After the polymerization and before allowing the product to heat up, the initiator is either extracted with a suitable selective solvent or a weak acid is added, if sufficient is not already present, to render it ineffective as a degradation catalyst on raising the temperature to that at which degradation of the polymer would normally occur. Aldehydes specified are formaldehyde, propionaldehyde, n-butyraldehyde, n-valeraldehyde, iso-valeraldehyde, n-caproaldehyde, cyclohexaldehyde, 2-ethyl hexaldehyde, benzaldehyde and phenyl acetaldehyde. The polymerization may be effected in organic solvents that are liquid at the temperature of the polymerization and a number of these are specified. In the examples, n-butyraldehyde is polymerized in pentane solution and in the presence of butyric acid with as the initiator either sodium N,N-diethyl-2-amino ethoxide or sodium N,N-dimethyl-3-amino n-propoxide at -78 DEG C., acetone is added to the resultant polymer solution with additional butyric acid if necessary and the mixture is allowed to warm up to room temperature. Thermal instability of the polymers may be reduced by reacting the polymer with compounds to replace its terminal hydroxyl groups with more stable groups, such as carboxylate, by etherification or by the heat treatment described in Specification 980,516. The polymers may be formed into shaped articles such as films, sheets, fibres and filaments. Conventional polymer composition additives may be incorporated.ALSO:Catalysts, used for the low temperature polymerization of aldehydes (see Division C3), consist of compounds having an alkali metal, alkaline earth metal, boron, aluminium, germanium, tin or lead atom directly linked to a monovalent group of the structure:- -O-CmH2m-NR2 where m is a positive integer and R is a monovalent hydrocarbon radical or hydrogen. Monovalent hydrocarbon radicals specified are methyl, ethyl, propyl, isopropyl, isomeric butyl, cyclohexyl, phenyl, benzyl and tolyl radicals. Catalysts exemplified are sodium N, N-diethyl-2-amino ethoxide and sodium N, N-dimethyl-3-amino n-propoxide.