Patent GB-793428-A (GB)
Title: A process for the preparation of branched chain alcohols and hydrocarbons
IPC: C07C9/00
Filed: 1956-11-02
Abstract: Branched-chain alcohols containing at least one group of the formula <FORM:0793428/IV (b)/1> where A represents hydrogen, a hydroxyl or an alkyl group, are prepared by heating a saturated organic compound containing at least one group of the formula <FORM:0793428/IV (b)/2> in the presence of a peroxidic compound, with formaldehyde or a compound which liberates formaldehyde under the conditions of the reaction.  The methylol group so introduced may subsequently be converted to a methyl group giving a branched chain hydrocarbon. The reaction is carried out in the liquid or vapour phase.  In the preferred method, the saturated compound is present in a liquid phase in which an organic peroxide is dissolved and the aldehyde in a separate, generally aqueous liquid phase.  The saturated compounds are advantageously paraffins with at least 3C, cycloparaffins and corresponding alcohols.  Suitable starting materials include normal paraffins, e.g. C3-35 normal paraffins, branched paraffins, cycloparaffins, e.g. C3-8 monocyclic paraffins including alkyl substituted derivatives and polycyclic paraffins such as decahydronaphthalene, petroleum fractions such as paraffinic naphthas, extracted kerosenes and petroleum waxes.  The secondary alcohols derived from the above are also suitable, e.g. isopropanol, 2-butanol, 3-heptanol, secondary hexadecanol and cyclohexanol. Particularly preferred are cyclopentane and cyclohexane; paraffin waxes are also preferred, e.g. those containing C18-30 molecules. The products obtained from the waxes are a mixture of methylol derivatives which may contain one or several methylol groups spaced along the chain.  The products may be converted to the corresponding saturated hydrocarbons, for example by dehydration to the olefine, e.g. by contact with alumina at elevated temperature, followed by catalytic hydrogenation, or directly by hydrogenolysis.  Such branched chain hydrocarbons derived from paraffin waxes form low-melting lubricants.  For liquid phase operation, the peroxidic compound should be at least partly, and preferably completely, soluble in the organic phase. Particularly suitable are organic peroxides such as tertiary alkyl peroxides, tertiary alkyl esters of peracids, diacyl peroxides, normal and secondary alkyl peroxides and those hydroperoxides which are predominantly oil-soluble, e.g. tertiary-butyl hydroperoxide.  Many are specified.  From 0.2 to 50, preferably from 5 to 25, mols. of organic compound are suitably employed per mol. of formaldehyde.  If it is desired to produce a substantial proportion of product containing more than one methylol group per molecule, low ratios are used, e.g. 0.2 to 1.  The amount of peroxide should be 0.01-0.4, preferably 0.05-0.1 mols. per mol. of formaldehyde.  The liquid phase reaction is carried out at 60-200 DEG C., preferably 120-155 DEG  C., the temperature being chosen such that the half-life of the peroxide is 0.5-6 hours.  Reaction temperatures in the lowest part of the range may be used when gaseous formaldehyde is added to the organic phase containing lauroyl peroxide.  In the vapour phase, higher temperatures up to and exceeding 200 DEG  C. are preferred.  The reaction time in the liquid phase is desirably at least 2 and preferably about 3 peroxide halflives.  The half-life is preferred to be 2-4 hours giving a preferred reaction time of 6-12 hours, although 2-24 hours is suitable.  In the vapour phase, higher temperatures, hence shorter halflives and shorter contact times, as low as 10 seconds to 1 minute, may be preferred. In liquid-phase operation, sufficient pressure is used to maintain the reactants in liquid phase and the formaldehyde in solution, e.g. up to 36 atmospheres or more, usually 10-18 atmospheres at preferred temperatures.  In vapour phase operation, atmospheric pressure may be used.  The reaction may be carried out batchwise or in a continuous manner.  It may also be carried out in the vapour phase, when the catalyst may also be gaseous or fixed on a bed of any suitable material.  Fluidized bed techniques may also be used.  The desired alcohols may be recovered from the organic phase and any aqueous phase may be recycled.  In examples: (1) cetane is heated with formalin in the presence of di-tert.-butyl peroxide and ethanol to give predominantly monohydric C17 alcohol; (2) cyclohexane similarly yields cyclohexyl carbinol; (3) cyclohexyl carbinol is prepared similarly from cyclohexane and paraformaldehyde; (4) mixed alcohols from n-hexane and (5) mixed alcohols from nonacosane (C29H60) are prepared as in (2); (6) mixed alcohols containing at least some molecules with more than one methylol group are prepared from octadecane as in (2); (7) cyclopentyl carbinol is prepared from cyclopentane as in (2); (8) the reaction product of (5) is passed through a quartz tube packed with alumina at 435-450 DEG  C. and hydrogenated over Raney nickel to give a saturated hydrocarbon; (9) gaseous formaldehyde is passed into a solution of lauroyl peroxide in cyclohexane under reflux conditions to give cyclohexyl carbinol; (10) mixed alcohols are prepared from methyl-cyclopentane as in (2).