GB699075A - Ethers of hydroxy aldehydes - Google Patents

Abstract

The invention comprises olefinic-unsaturated ethers of hydroxy aldehydes which may be prepared by reacting a primary olefinic p alcohol containing one or more double bonds with an a : b - olefinic unsaturated aldehyde in the presence of an alkaline condensation catalyst at a temperature below +10 DEG C. The unsaturated ethers include those having the formula <FORM:0699075/IV (b)/1> wherein R1 is hydrogen, an alkyl or a phenyl group, R2 is hydrogen or an alkyl group and -OR3 represents the residue of allyl alcohol, methyl-, ethyl-, propyl- or other 2-alkyl substituted allyl alcohol, cyclohexyl allyl alcohol or cinnamyl alcohol. As alkaline condensation catalysts there may be used sodium or potassium hydroxide, alkali metal alkoxides, e.g. those of the primary olefinic alcohol reactant, organic bases such as triethylamine and quaternary ammonium bases, e.g. trimethyl benzyl ammonium hydroxide; they may be used in aqueous or alcoholic solution. The alcohol is preferably used in large excess over the unsaturated aldehyde. The ethers formed may be recovered by acidifying the mixture, e.g. with phosphoric acid, if desired after neutralization with an acid, preferably an organic acid, e.g. acetic acid, and then distilling. The unsaturated ethers of the aldehydes may be converted into acetals by reaction with alcohol in the presence of an acidic condensation catalyst. The ethers may also be saturated in the olefinic double bond by selective hydrogenation generally at between 15 DEG and 50 DEG C. under pressures of up to 3 to 5 atmospheres and using not more than one mole. of hydrogen per mole. of ether-aldehyde, a suitable catalyst being palladium or charcoal. The unsaturated ethers may also be used as intermediates for the manufacture of polymers and oxidation products. The saturated ethers containing propoxy and butoxy groups may be converted into corresponding acids and alcohols which may be used to produce esters forming high-boiling solvents or plasticizers. In examples: (1) acrolein is reacted with allyl alcohol in aqueous sodium hydroxide at -10 DEG C., yielding 4-oxahept-6-enal; the unsaturated ether-aldehyde is reacted with ethanol using H2SO4 as catalyst to form its acetal; the ether is also hydrogenated in ethanol solution using Adam's catalyst to form 4-oxaheptanal; (2) methacrolein is similarly reacted with allyl alcohol to form 2-methyl-4-oxahept-6-enal which on hydrogenation yields 2 - methyl - 4 - oxaheptanal; (3) acrolein and methyl allyl alcohol are likewise reacted to form 6 - methyl - 4 - oxahept - 6 - enal which is then hydrogenated to 6-methyl-4-oxaheptanal; (4) crotonaldehyde and allyl alcohol similarly yield 3 - methyl - 4 - oxahept - 6 - enal which is hydrogenated to 3-methyl-4-oxaheptanal. The semi-carbazones and 2 : 4-dinitrophenyl hydrazones of the unsaturated and saturated ether-aldehydes are described. Cinnamyl aldehyde is also mentioned as an aldehydic reactant.