Patent GB-613444-A (GB)
Title: Improvements in and relating to the production of heterocyclic compounds
IPC: C07D493/04
Filed: 1946-01-17
Abstract: In a process for producing oxygen-containing heterocyclic compounds by dehydration of aliphatic compounds having a straight chain of 5 or 6 carbon atoms and containing at least two pairs of hydroxyl groups, the hydroxyl groups of each pair being attached respectively to the carbon atoms of said chain, which are themselves separated from one another by two carbon atoms and of derivatives thereof in which at least one pair of the aforesaid hydroxyl groups are unsubstituted (see Group IV) the compounds are refluxed under dehydrating conditions in the presence of an acidic substance as catalyst and of an inert organic liquid which forms an azeotrope or heteroazeotrope with water and the water of dehydration is removed by azeotropic distillation.  The inert organic liquid is preferably substantially immiscible with water and is preferably a solvent for the reactants and products, or an inert organic liquid which yields a homogeneous distillate with water may be employed.  The reaction temperature is preferably not less than 130 DEG  C. and suitable inert organic liquids are xylene, toluene and their homologues and a higher alcohol mixture consisting of isomeric heptanols and octanols and having a boiling point of about 160 DEG  C.  In an example D-sorbitol is dehydrated to form 1,4-3,6-dianhydro sorbitol by refluxing with about an equal weight of xylene in the presence of p-toluene sulphonic acid until no more water is evolved.  Specification 396,761 and 408,230, [Group IV], are referred to.ALSO:Oxygen containing heterocyclic compounds are obtained from aliphatic compounds containing no carboxylic or substituted carboxylic groups and having a straight chain of 5 or 6 carbon atoms and at least two pairs of hydroxyl groups of alcohol type, the hydroxyl groups of each pair being attached respectively to two carbon atoms of said chain which are themselves separated from one another by two carbon atoms, none of the said hydroxyl groups in said aliphatic compounds being attached to the same carbon atom, or from substituted derivatives of said compounds in which the substituent groups are non-reactive and in which at least one pair of the aforesaid hydroxyl groups are unsubstituted by subjecting said compounds or derivatives to reflux under dehydrating conditions in the presence of an acidic substance as catalyst and of an inert organic liquid which forms an azeotrope or hetero-azeotrope with water and removing the water of dehydration by azeotropic distillation.  The desired product may be obtained by removing the remaining inert liquid from the residue, e.g. by distillation.  Specified starting materials are the pentahydric and hexahydric alcohols, e.g. sorbitol, mannitol, dolcitol and D-xylitol which yield derivatives containing two tetrahydro-furanoid rings and as substituted derivative the lactone of gluconic acid is mentioned. The reaction product may be esterified after partial or complete removal of the inert organic liquid therefrom by refluxing with an esterifying acid. The inert liquid is preferably substantially immiscible with water and is preferably a solvent for the reactants and products.  An inert liquid which yields a homogeneous distillate with water may also be employed.  The reaction temperature should preferably be not less than 130 DEG  C. and xylene, toluene and their homologues and a higher alcohol mixture consisting of isomeric heptanols and octanols and having a boiling point of about 160 DEG C. are suitable as inert organic liquids.  The reaction may be conducted at atmospheric, reduced or super-atmospheric pressure and the inert liquid which distils over with the water may be dehydrated and recycled to the still or column used for the reaction.  The acidic catalysts may be acids or salts, thus inorganic acids such as sulphuric, phosphoric and mixtures thereof and strong organic acids, e.g. oxalic acid, are suitable, but it is preferred to employ an aromatic sulphonic acid, e.g. p-toluene sulphonic acid. Suitable acids for esterifying the products are the saturated aliphatic mono-carboxylic acids, e.g. acetic, propionic, butyric, stearic; and acrylic, oleic, naphthenic, benzoic, oxalic, succinic, maleic and phthalic acids.  In an example, D-sorbitol is refluxed with about an equal weight of xylene in the presence of p-toluene sulphonic acid until no more water is evolved, the remaining xylene is removed from the residue under reduced pressure and the residue distilled under reduced pressure to give 1,4-3,6-dianhydro-sorbitol.  The di-butyrate and the di-tetrahydrofuroate may be prepared by adding a slight excess of butyric or of tetrahydrofuroic acid and continuing to reflux till no more water is removed and then isolating the esters by vacuum distillation.  The anhydro compounds, particularly the anhydro sorbitols, are useful as emulsifying agents for the production of water in oil emulsions and in cosmetics as wetting agents, while the esters are valuable as softeners and plasticizers for resins and cellulosic materials, e.g. vinyl resins, nitro - cellulose and cellulose.  Specifications 396,761 and 408,230 are referred to. The Provisional Specification refers also to the dehydration of acetone condensation products of hexahydric alcohols, e.g. 3-, 4-monoacetone mannitol.ALSO:Oxygen containing heterocyclic compounds are obtained from aliphatic compounds containing no carboxylic or substituted carboxylic groups and having a straight chain of 5 or 6 carbon atoms and at least two pairs of hydroxyl groups of alcohol type, the hydroxyl groups of each pair being attached respectively to two carbon atoms of said chain which are themselves separated from one another by two carbon atoms, none of the said hydroxyl groups in said aliphatic compounds being attached to the same carbon atom, or from substituted derivatives of said compounds in which the substituent groups are non-reactive and in which at least one pair of the aforesaid hydroxyl groups are unsubstituted p  by subjecting said compounds or derivatives to reflux under dehydrating conditions in the presence of an acidic substance as catalyst and of an inert organic liquid which forms an azeotrope or hetero-azeotrope with water and removing the water of dehydration by azeotropic distillation.  The desired product may be obtained by removing the remaining inert liquid from the residue, e.g. by distillation. Specified starting materials are the pentahydric and hexahydric alcohols, e.g. sorbitol, mannitol, dulcitol and D-xylitol which yield derivatives containing two tetrahydro-furanoid rings and as substituted derivative the lactone of gluconic acid is mentioned. The reaction product may be esterified after partial or complete removal of the inert organic liquid therefrom by refluxing with an esterifying acid. The inert liquid is preferably substantially immiscible with water and is preferably a solvent for the reactants and products.  An inert liquid which yields a homogeneous distillate with water may also be employed.  The reaction temperature should preferably be not less than 130 DEG  C. and xylene, toluene and their homologues and a higher alcohol mixture consisting of isomeric heptanols and octanols and having a boiling point of about 160 DEG C. are suitable as inert organic liquids.  The reaction may be conducted at atmospheric, reduced or superatmospheric pressure and the inert liquid which distills over with the water may be dehydrated and recycled to the still or column used for the reaction.  The acidic catalysts may be acids or salts, thus inorganic acids such as sulphuric, phosphoric and mixtures thereof and strong organic acids, e.g. oxalic acid are suitable but it is preferred to employ an aromatic sulphonic acid, e.g. p-toluene sulphonic acid. Suitable acids for esterifying the products are the saturated aliphatic mono-carboxylic acids, e.g. acetic, propionic, butyric, stearic; and acrylic, oleic, naphthenic, benzoic, oxalic, succinic, maleic and phthalic acids.  In an example, D-sorbitol is refluxed with about an equal weight of xylene in the presence of p-toluene sulphonic acid until no more water is evolved, the remaining xylene is removed from the residue under reduced pressure and the residue distilled under reduced pressure to give 1,4-3,6-dianhydro-sorbitol.  The di-butyrate and the di-tetrahydrofuroate may be prepared by adding a slight excess of butyric or of tetrahydrofuroic acid and continuing to reflux till no more water is removed and then isolating the esters by vacuum distillation.  The anhydro compounds, particularly the anhydro sorbitols, are useful as emulsifying agents for the production of water in oil emulsions and in cosmetics as wetting agents, while the esters are valuable as softeners and plasticisers for resins and cellulosic materials, e.g. vinyl resins, nitro-cellulose and cellulose.  Specifications 396,761 and 408,230 are referred to.  The Provisional Specification refers also to the dehydration of acetone condensation products of hexahydric alcohols, e.g. 3,4-mono-acetone mannitol.