Patent GB-645956-A (GB)
Title: A process for the manufacture of beta-acyloxy-aldehydes, carboxylic acids, glycols and glycol mono-esters
IPC: C07C51/377
Filed: 1948-02-11
Abstract: Resins are prepared by condensing with, for example, urea, phenols or melamine, b -formoxy-aldehydes such as b -formoxy-propionaldehyde or butyraldehyde, and b -phenyl, cyclohexyl, chlor, methyl, ethyl or isopropyl, g -tolyl, a -methyl, and b ,b -diethyl derivatives thereof.ALSO:b -Acyloxy-aldehydes are made by heating a carboxylic acid with an a ,b -unsaturated aldehyde under non-polymerizing conditions. The carboxylic acid may be aliphatic, cycloaliphatic, aromatic or heterocyclic, for example formic, acetic, propionic, butyric or p  isobutyric, cyclohexane carboxylic, benzoic, phenylacetic, acrylic, methacrylic, 2-cyclohexene-carboxylic, and b -phenylacrylic acids, which may contain inert substituents such as fluorine, bromine, chlorine or ether groups.  The unsaturated aldehydes have the grouping <FORM:0645956/IV (b)/1> or -C­C-CHO, preferably <FORM:0645956/IV (b)/2> They are exemplified by acrolein, methacrolein, crotonaldehyde, tigilic and propargyl aldehydes, a  - ethylcrotonaldehyde, 2 - cyclohexenecarboxaldehyde, b -cyclohexyl-, b -phenethyl-, and b -chlor-acrolein.  The mixture of acid and aldehyde, desirably in molar rates of 2-6 : 1, and if necessary a solvent or homogenizing medium such as hydrocarbons or their halogenated derivatives, ethers, and esters, is heated to about 50-160 DEG  C., preferably in the liquid phase.  Electrolytes, preferably acidic, such a acids and acid-reacting salts, may be added as catalysts, also anti-oxidants such as hydroquinone.  Formic acid with the olefinically unsaturated aldehydes gives aldehydes having the grouping <FORM:0645956/IV (b)/3> , preferably <FORM:0645956/IV (b)/4> , such as b -formoxy-propionaldehyde and its homologues. Other acyloxy-aldehydes include b -acetoxy-butyraldehyde, b -valeroxy-, b -stearyloxy-, b -phenoxyacetoxy-, and b -benzoxy-propionaldehyde, the cyclohexane-carboxylic acid, 2,4-dichlorbenzoic acid, and b -methoxypropionic acid esters of b  - hydroxypropionaldehyde, the palmitic acid ester of b -hydroxyvaleraldehyde, and the b -chlorbutyric acid ester of b -hydroxybutyraldehyde.  In examples, acrolein is heated with acetic or formic acid under autogenous pressure to yield b -acetoxy- or formoxy-propionaldehyde.  b -Acyloxy-carboxylic acids are prepared from the aldehydes by the action of oxygen-containing gas and an oxidation catalyst, preferably in an acidic, organic solvent such as acetic acid or a mixture thereof with other solvents.  Salts of metals of Groups 7 and 8 such as Co, Mn, Ni, Fe, Pt or Ir, or the metals or their oxides, are suitable catalysts.  Cobalt chelate salts of b -diketones, soluble in the reaction medium, are preferred, especially cobalt acetylacetonate.  Reaction temperatures are suitably 40-90 DEG  C.  In an example, b -acetoxy-propionaldehyde in glacial acetic acid containing cobalt acetyl-acetonate is treated with a stream of oxygen at 60 DEG  C., giving b -acetoxy-propionic acid.  Acrylic acid.-b -Acyloxy-propionic acids prepared as above are pyrolyzed, preferably at 170-300 DEG  C., and in liquid phase, to form acrylic acid and an acid corresponding to the acyloxy group which preferably has a sufficiently different boiling point to permit separation by distillation.  The acyloxy group is suitably derived from a saturated fatty acid of up to 8 carbon atoms. Solid contact materials or catalysts such as zinc chloride or calcium chloride, and anti-oxidants may be present.  In examples, b -acetoxy-propionic acid containing hydroquinone is heated to 186 DEG  C. in a reactor or passed through a reaction tube at 190 DEG  C., acrylic acid being recovered.  1,3-Alkanediols and their mono-esters.-The b -acyloxy-aldehydes on catalytic hydrogenation yield mono-esters of 1,3-alkanediols. The catalyst is preferably a base metal such as nickel treated so that a 2 per cent dispersion in water has a pH of less than 8.5, preferably 4.5-7.  Raney nickel may be treated with acid-reacting material as by suspending in water and adding an acid or salt to give the desired pH or washing with a buffer solution. Other nickel catalysts or cobalt or copper with, if desired, promoters such as salts of metals of Groups 2 to 6, and supporting materials, may be used similarly.  Temperatures for the hydrogenation are about 10-100 DEG  C. and hydrogen pressures 250-5000 p.s.i. Inert solvents may be present.  Saturated aliphatic b -acyloxy-alkanals containing up to 10 carbon atoms are particularly suitable for hydrogenation.  The esters can be hydrolysed to the respective 1,3-glycols, such as propane- and butane-diols.  In an example, Raney nickel is dispersed in water and treated with sulphuric acid until the pH is 6.6, filtered, and washed free from sulphate and water.  It is suspended in a solution in dioxane of b -acetoxy - propionaldehyde, which is hydrogenated to yield 3-acetoxy-propanol.ALSO:A catalyst for the hydrogenation of a b -acyloxy-aldehyde to a mono-ester of a 1,3-alkanediol is a base metal such as nickel treated so that a 2 per cent dispersion in water has a pH of less than 8.5, preferably 4.5-7.  Raney nickel may be treated with acid-reacting material as by suspending in water and adding an acid or salt to give the desired pH or washing with a buffer solution.  Other nickel catalysts or cobalt or copper with, if desired, promoters such as salts of metals of Groups 2 to 6, and supporting materials, may be used similarly.  Inert solvents may be present.  In an example, Raney nickel is dispersed in water and treated with sulphuric acid until the pH is 6.6, filtered, and washed free from sulphate and water.