Patent GB-580383-A (GB)
Title: Improvements in or relating to the manufacture of aldehydes
IPC: C07C45/74
Filed: 1944-06-12
Abstract: Unsaturated aldehydes of 8 or more carbon atoms are prepared by maintaining a mixture initially comprising crotonaldehyde with 10-30 per cent of its weight of water and with an aliphatic alcohol of not more than 4 carbon atoms, to which a secondary amine or salt thereof is added as catalyst, at a temperature of 40-60 DEG  C. for 3-12 hrs. in the absence of free inorganic acid or of more than a small amount, viz., about 25 per cent of the equivalent of the amine, of a free organic acid without removing water.  The amount of water is preferably 10-20, especially about 15 per cent.  The alcohol may be ethyl, propyl, isopropyl or butyl, and is preferably 50-150 per cent of the weight of crotonaldehyde, although all may not be present initially. Atmospheric pressure is generally used and air replaced by inert gas.  Secondary amines include dimethyl, diethyl, dipropyl and dibutyl amines, dicyclohexylamine and the preferred heterocyclic amines, e.g. piperidine, piperazine, hydrogenated quinolines, hydrogenated thiazines, morpholine and tetrahydro-pyrrole, which are preferably employed as salts with weak inorganic acids, e.g. boric, or carboxylic acids, e.g. acetic, formic, succinic, crotonic, valeric, glycollic, chlorpropionic, and malic. Preferably, morpholine acetate or piperidine acetate equivalent to 1-8 per cent of free amine on the weight of crotonaldehyde is used.  The catalyst may be added before or after, or partly before and after heating to the reaction temperature.  The amine and acid may be added separately. After removing alcohol, unreacted crotonaldehyde, and catalyst, the aldehydes produced may be recovered by fractional distillation or recrystallization.  They may be hydrogenated to yield mono- and poly-hydroxy alcohols which are anti-foaming agents and which may be sulphated to give sulphuric esters which are wetting agents.  In an example, 280 parts crotonaldehyde, 80 methyl alcohol, 30 water and 16 acetic acid are heated to 45 DEG  C. in an atmosphere of N2 or CO2, 10 parts of morpholine in 40 of methyl alcohol added, the mixture heated to 50 DEG  C. for 2 hrs., a second similar addition made, followed by heating at 50 DEG  C. for 8 hrs.  The aldehyde product is recovered by crystallization from dilute alcohol.  It is hydrogenated in methyl alcohol at 1500-1800 lbs./sq. in. hydrogen pressure for 3 hrs. each at 50 DEG , 100 DEG  and 130 DEG  C. using Raney nickel. The alcohols, if desired after separating by fractionation, may be treated at 15 DEG  C. with chlorsulphonic acid and the product neutralized with caustic soda to give a wetting, detergent and emulsifying agent utilizable in hard water or acid or salt solution. The Specification as open to inspection under Sect. 91 comprises the preparation of high molecular weight aldehydes and ketones generally by condensation of aldehydes and/or ketones containing reactive methylene or methyl groups in the presence of lower aliphatic alcohols and water.  Examples of suitable aliphatic, cyclo-aliphatic, aromatic and mixed aldehydes and ketones are given.  Substituent, for example halogen or hydroxy, groups may be present.  This subject-matter does not appear in the Specification as accepted.