Patent GB-798211-A (GB)
Title: A new process for the manufacture of polyene-dials and polyene-diones
IPC: A23L5/47
Filed: 1957-04-04
Abstract: Polyene-dials or polyene-diones are produced by a process comprising reacting an alkali-metal salt of a nitronic acid with a dihalogenated hydrocarbon containing a double bond in the a ,b -position to each halogen and at least one further carbon-to-carbon multiple bond. Suitable dihalogenated compounds are, for example, 1,8 - dichloro - octatriene - (2,4,6), 1,8 - dibromo-octadien - (2,6) - yne - (4), 2,9 - dichloro - decadien - (3,7) - yne - (5), 2,9 - dibromo - decatriene-(3,5,7), 1,9 - dichloro - decadien - (2,7) - yne - (5), 1,8 - dichloro - 2,7 - dimethyl - octatriene - (2,4,6), 1,8 - dibromo - 2,7 - dimethyl - octadien-(2,6) - yne - (4), 2,9 - dichloro - 3,8 - dimethyl - decadien - (3,7) - yne - (5), 2,9 - dibromo - 3,8 - dimethyl - decatriene - (3,5,7) and 1,10 - dichloro - 2,7,8 - trimethyl - decatrien - (2,6,8) - yne-(4).  Particularly suitable as starting materials are dihalides containing a central triple bond such as 1,8-dihalogeno-2,7-dimethyl-octadien-(2,6)-yne-(4)s, 2,9-dihalogeno-3,8-dimethyldecadien-(3,7)-yne-(5)s and 1,16-dihalogeno - 2,6,11,15 - tetramethyl - hexadecahexaen - (2,4,6,10,12,14) - yne - (8)s.  The nitronic acids are primary or secondary nitro compounds which react in an aci-form with alkalis such as alkali-metal hydroxides or alcoholates to form alkali salts. Alkali salts of lower aliphatic nitronic acids such as methane-, propane-(1)- or propane-(2)-nitronic acid and of alicyclic nitronic acids, such as cyclohexane nitronic acid, are preferred.  The reaction may be carried out in the presence of anhydrous or aqueous diluents, for example, a mono- or polyhydric alcohol, such as methanol, ethanol, isopropanol, tertiary butanol, monoethylene glycol or diethylene glycol; a water-soluble ether, such as diethylene glycol ethyl butyl ether, dioxane or tetrahydrofurane; a dialkyl amide, such as dimethylformamide; an acetal, such as methylal; a ketone, such as acetone; or acetonitrile.  The reactants are conveniently mixed in the diluent at a temperature between - 10 DEG and 40 DEG  C.  In the examples (a) a solution obtained by adding 2-nitro-propane to sodium hydroxide solution is added to 1,8-dibromo-2,7-dimethyl - octadien - (2,6) - yne - (4) in methanol solution to give 2,7-dimethyl-octadien - (2,6) - yne - (4) - dial - (1,8); (b) a solution obtained by adding 2-nitropropane to potassium hydroxide solution is added to 1,8-dibromo-2,7-dimethyl-octadien - (2,6) - yne - (4) in ethanol solution to give the same product as in (a); (c) to a solution obtained by adding 2-nitro-propane to a mixture of potassium hydroxide and dimethyl formamide is added 1,8-dibromo-2,7-dimethyl-octadien-(2,6)-yne-(4) to give the same product as in (a); (d) 2,9-dibromo-3,8-dimethyl-decadien-(3,7)-yne-(5) is added to the mixture obtained by adding 2-nitro-propane to a mixture of potassium hydroxide and acetone to give 3,8 - dimethyl - decadien - (3,7) - yne - 5 - dione - (2,9); (e) 2,9 - dibromo - 3,8 - dimethyl-decadien-(3,7)-yne-(5) is added to the mixture obtained by mixing potassium hydroxide with isopropanol and 2-nitro-propane to give the same product as in (d); (f) the mixture obtained by mixing 2-nitropropane with potassium hydroxide and dimethyl formamide is reacted with 2,9 - dibromo - 3,8 - dimethyl - decadien - (3,7)-yne-(5) to give the same product as in (d); and (g) the mixture obtained by mixing 2-nitropropane with potassium hydroxide and dimethyl formamide is reacted with 2,9-dichloro-3,8-dimethyl-decadien-(3,7) -yne-(5) to give the same product as in (d).  The dihalogenated hydrocarbons used as starting materials may be obtained, for example, by halogenating the corresponding diols with a phosphorus trihalide or a hydrohalic acid in an inert solvent.  They may also be obtained from isomeric diols by halogenation and allyl rearrangement.  Thus 1,8 - dihalogeno - 2,7 - dimethyl - octadien - (2,6) - yne - (4) may be obtained from 1,8-dihydroxy-2,7-dimethyl-octadien - (2,6) - yne - (4) as well as from 2,7 - dimethyl - 3,6 - dihydroxy - octadien - (1,7) - yne - 4. The starting material in (d) above is prepared by condensing 2 mols. of tiglic aldehyde with one mol. of acetylene-di(magnesium bromide) and brominating the resulting 3,8-dimethyl - 4,7 - dihydroxy - decadien - (2,8) - yne - (5) with phosphorus tribromide.  The corresponding dichloro compound is prepared by treating 2 mols. of tiglic aldehyde with one mol. of acetylene di(magnesium bromide) and treating the 3,8-dimethyl-4,7-dihydroxy-decadien-(2,8)-yne-(5) with dilute sulphuric acid to give 3,8 - dimethyl - 2,9 - dihydroxy - decadien - (3,7)-yne-(5) which is chlorinated with phosphorus trichloride.