Patent GB-571777-A (GB)
Title: Manufacture of new unsaturated alcohols and esters and ethers thereof
IPC: C07C33/02
Filed: 1944-02-10
Abstract: A dienol of the formula RR1C(OH)CR2= CR3CH=CR4R5, where R, R1, R2, R3 and R4 are hydrogen or alkyl groups of not more than 6 carbon atoms, and R5 is hydrogen, an alkyl group of not more than 4 carbon atoms, a vinyl, methylvinyl or dimethylvinyl group, is prepared by subjecting a dienol of the formula RR1C=CR2CR3(OH)CH=CR4R5 to the actio of a mineral acid, an acid salt, an organic acid or an esterifying derivative of a mineral or organic acid.  An aqueous solution of the acid of, for example, 2.5-25 per cent concentration may be used or a solvent such as ethanol may be present.  Temperature may range from normal up to, say, 100 DEG  C. The isomerized dienol may be isolated in the form of an ester, for example, when using acetic anhydride, or with hydrochloric or sulphuric acid of high concentrations and at high temperatures. With an acidic substance such as sulphuric acid in an alcoholic solvent such as methanol, ethanol or ethylene chlorhydrin, etherification of the isomerized dienol may occur.  The products are intermediates for the manufacture of polymeric materials.  The initial dienols may be obtained, where R4 is hydrogen, by the partial hydrogenation of ethinylcarbinols of the formula RR1C=CR2CR3(OH)C­CR5.  Thus, vinylethinylcarbinol, CH2=CH.CH(OH)C­CH, gives divinylcarbinol, CH2=CH.CH(OH).CH= CH2. Other dienols prepared in this way are propenylvinyl and 2-methylpropenylvinylcarbinols, 4 - ethyloctadien - 1,4 - ol - 3, 3 - methyl - nonatrien - 2,4,7 - ol - 6, octatrien - 1,3,6 - ol - 5, 2 - methyloctatrien - 1,3,6 - ol - 5, 2,7 - dimethyloctatrien - 1,3,6 - ol - 5, 2 - methyl - 6 - ethyl - decatrien - 1,3,6 - ol - 5, 6 - ethyldecadien - 3,6 - ol - 5, and 3,5 - dimethylhexadien - 1,4 - ol - 3.  The ethinyl - carbinols may themselves be obtained by condensing an unsaturated aldehyde or ketone, e.g. acrolein, crotonaldehyde, 2-ethylhexen-2-al-1,2-methylcrotonaldehyde or mesityl oxide, with alkali metal acetylides derived from, e.g. acetylene or ethyl-, vinyl-, or 1-2-dimethyl-vinyl-acetylene, as described in U.S.A. Specifications 2,125,384 and 2,106,180-2.  Where R4 is an alkyl radical, the initial dienols may be prepared by reducing the corresponding ketone.  Thus, phorone yields 2,6-dimethylheptadien-2,5-ol-4.  Other acidic substances referred to for effecting the isomerization are boric, phosphoric, nitric, formic, acetic, and tartaric acids and potassium bisulphate.  In examples: (1) propenylvinylcarbinol is shaken with 1 per cent aqueous sulphuric acid for 2 hrs. at 15-20 DEG  C. in an atmosphere of nitrogen, the product ether extracted, dried, and distilled to give hexadien-1,3-ol-5; (2) using a methanol solution of the acid and standing for 4 days at 20 DEG  C., adding water, and extracting as before yields 5-methoxyhexadien-1,3; (3) acetic anhydride is used for 2 hrs. at steam bath temperature, water added to hydrolyse the anhydride, and the product, 5-acetoxyhexadien-1,3, extracted; (4) 5-ethoxyhexadien-1,3 is obtained using sulphuric acid in ethanol; (5) 3-methylhexadien-1,4-ol-3, aqueous sulphuric acid, and a trace of hydroquinone at 20 DEG  C. for 25 mins, yield 4-methylhexadien-3,5-ol-2; (6) divinylcarbinol with aqueous sulphuric acid at 20 DEG  C. for 24 hrs. yields pentadien-2,4-ol-1 which, on standing in air, slowly changes to a transparent polymer; (7) isopropenylvinylcarbinol similarly gives 2-methylpentadien-2,4-ol-1; (8) propenylvinylcarbinol, ethylene chlorhydrin and sulphuric acid after 2-5 days at atmospheric temperature yield 2-b -chlorethoxyhexadien-3,5.