GB757309A - The manufacture of polyoxyalkylene glycols and their mono-ethers - Google Patents

Abstract

Polyoxyalkylene glycols or mono-ethers thereof containing at least 4 oxypropylene units in the molecule and having molecular weights up to 4000 are formed by continuously passing a homogeneous mixture of 1,2-propylene oxide with or without ethylene oxide, an organic hydroxy compound and an alkali metal catalyst through a reaction zone maintained by removal of heat of reaction at 50-190 DEG C. under a pressure sufficient to maintain the mixture liquid, e.g. 7-130 atmospheres, the contact time in the reaction zone being 5-60 minutes and 25-97 per cent of the alkylene oxides being reacted. Suitable hydroxy compounds are: glycols, e.g. ethylene, propylene, polyoxyethylene or polyoxypropylene glycol, 2,21-thiodiethanol; monohydric alcohols having up to 20 carbon atoms/molecule, e.g. n-butyl, lauryl or benzyl alcohol or 2-ethyl hexanol or mono-ethers of glycols with one of their monohydric alcohols; mono- or di-hydric phenols or naphthols, e.g. phenol, b -naphthol, cresol, octyl phenol or octyl cresol. Initial heating of reactants and cooling during the reaction are preferably provided by surrounding the reactor with a boiling liquid, e.g. blends of water with ethylene glycol or ethylene glycol monobutyl ether. Suitable alkali metal catalysts are sodium, potassium or lithium generally dissolved as the hydroxide or alkoxide in the hydroxy compound. Preferred catalyst concentrations are 0.0005-0.4 gm. mols./litre of reactants. The oxides used in the process may be dried and freed from aldehyde or acid impurities by passage through a bed of solid caustic soda or potash. In carrying out the invention the aqueous alkaline catalyst was dissolved in the hydroxy compound, water distilled off and the material cooled. The alkylene oxide and alkali-containing hydroxy compound were separately pumped in desired proportions by pumps 11, 12 from supply lines 13, 14 to a mixer 17, and through a stainless steel reactor coil 19 immersed in boiling liquid 21 in a vessel 20. The reacted liquids pass through pipe 25 to needle let-down valve 26, and pipe 27 to still 28. Unreacted oxides are recycled by pipe 32 and the reaction product is pumped by pump 29 to cooler 31 and thence to storage. Examples describe the conditions used in the reaction of diethylene glycol with mixed ethylene and propylene oxides, of dipropylene glycol with propylene oxide, of n-butanol with propylene oxide, of ethylene glycol monomethyl ether with propylene oxide and of polyoxyethylene glycol with propylene oxide. In other examples polyoxypropylene glycol is reacted with mixed ethylene and propylene oxides. The Specification describes the structure, molecular weights and physical properties of a number of the products obtained according to the invention. Products useful as heat-sensitizers for rubber, as lubricants, or as hydraulic brake fluids. Specifications 601,419, [Group IV (b)], 610,505 and 736,991 are referred to.