Patent GB-763434-A (GB)
Title: Manufacture of alkanolamines
Inventor: LOWE A J
Filed: 1951-08-30
Abstract: Alkanolamines are prepared from ethylene or 1,2-propylene oxide and an amine having no hydroxy group in the molecule and having at least one hydrogen atom attached directly to a nitrogen atom, by continuously passing a liquid mixture of the amine, alkylene oxide and water, the mixture containing not more than 50 per cent by weight of alkylene oxide, at least 20 and preferably 50-500 grams of water per litre of reaction mixture and at least a quantity of the amine sufficient for complete reaction of the alkylene oxide present, through a reaction zone maintained at a temperature ranging from a minimum of 80 DEG  to 150 DEG  C. to a maximum of 275 DEG  C., under a pressure ensuring that the reaction mixture is maintained in liquid state, the contact time within the zone not exceeding 2 hours and the amount of water present and the temperature being so adjusted that substantially complete reaction of the alkylene oxide occurs.  In a modification, all or part of the water in the reaction mixture is replaced by an organic hydroxy compound consisting of carbon, hydrogen and one or more alcoholic or phenolic hydroxy groups, with or without ethereal oxygen, the total content of water and organic hydroxy compound being equivalent in hydroxy content to at least 20, preferably at least 50, grams of water per litre, and not exceeding 50 per cent by volume of the mixture; specified hydroxy compounds are methanol, ethanol, butanol, ethylene glycol, glycerol and diethylene glycol. The reaction pressures are generally in excess of 60 atmospheres gauge.  The temperatures are preferably maintained below 150 DEG  C. Reaction times of 120 secs. or less may be achieved. Suitable apparatus is described comprising a coiled tubular reactor of stainless steel which is completely immersed in a bath of a boiling liquid such as water which serves both to heat the reactants to the desired temperature and prevent further temperature increase when the exothermic reaction proceeds.  In examples, this apparatus is employed in the reaction of (1) methylamine in water with ethylene oxide to give N-methyl diethanolamine and minor amounts of N-methyl ethanolamine and ethers of the main product; (2) diethylamine in methanol with propylene oxide to give 1-diethylamino-propane-2-ol and minor amounts of 1 - diethylaminopropoxy - 2 - propane - 2 - ol; (3) diethylamine in diethylene glycol with ethylene oxide to give diethylamino ethanol and some ethylene glycol mono diethylamino ethyl ether and unchanged amine, which is recycled together with minor amounts of byproducts; (4) dodecylamine in methanol with ethylene oxide to give N - dodecyl - diethanolamine useful as an emulsifying agent.  Other specified amino reactants include ethylamine, dimethylamine, octadecylamine, ethylene diamine, diethylene triamine, tetraethylene pentamine, aniline and morpholine.  According to the Provisional Specification, the hydroxy content of the reaction mixture is to be equivalent to at least 1 per cent by weight of water, the reaction temperature is to be between 80 DEG  and 300 DEG C. and the contact time to be sufficient for complete reaction.  The hydroxy compounds may be any organic hydroxy compound free from other groups reactive with alkylene oxides and the use of the alkanolamine products of the process is mentioned.  U.S.A. Specification 2,373,199 is referred to.