Patent GB-471914-A (GB)
Title: Improvements in or relating to the manufacture of cyclic esters
Filed: 1936-03-12
Abstract: <PICT:0471914/IV/1> Cyclic esters having rings of more than seven atoms are manufactured by depolymerizing the corresponding non-cyclic polyesters derived from dihydric alcohols and dibasic acids or lactone polymers derived from hydroxy acids, by heating them at a temperature within the range of about 150 DEG  C. up to the temperature at which substantial thermal decomposition will take place (about 375 DEG  C.), preferably at 250--275 DEG  C., under reduced pressure, below 10 mm., preferably below 1 mm., in the presence of a catalyst selected from the chlorides, nitrates, carbonates and oxides of magnesium, manganese, iron, cobalt, and tin, the said elements being in the divalent state, or in the presence of magnesium powder, the reaction being carried out in an apparatus designed to permit the volatile reaction products to distil continuously from the reaction mass and be collected, after condensation, in a suitable receiver.  A suitable apparatus consists of a vessel A fitted with a dephlegmator E and a receiver D (the latter being connected to a vacuum pump), and heated by the vapours of a liquid of suitable boiling point boiled in a vessel B.  The linear polyesters, which may be treated without purification, may be prepared by heating glycols, preferably in slight excess, with dibasic acids or with esters thereof, preferably in the presence of a small amount of sodium or other ester interchange catalyst.  Many of the cyclic esters, particularly those having rings of 15, 16 or 17 members, e.g. tetradecamethylene carbonate, monomethylene adipate, hexamethylene azelate, decamethylene succinate, ethylene brassylate and o -hydroxypentadecanoic lactone, may be employed as perfume ingredients.  In examples: (1) crude hexamethylene succinate polymer (obtained by heating hexamethylene glycol and succinic acid) is heated at 268 DEG  C. under 1 mm. pressure with hydrated stannous chloride, yielding a mixture of monomer and dimer; (2) decamethylene carbonate polymer (prepared by heating decamethylene glycol with butyl carbonate in the presence of stannous chloride) is similarly treated to produce the monomeric p  ester; (3) hexamethylene sebacate polymer is heated at 270 DEG  C. under 1mm. pressure with cobalt nitrate or chloride, stannous chloride, manganous chloride, ferrous chloride, magnesium chloride, oxide or carbonate, manganese carbonate or magnesium powder, producing the monomeric ester; (4) o -hydroxydecanoic acid lactone polymer is heated at 270 DEG  C. under 1 mm. or less pressure with magnesium chloride, yielding dimer and a little monomer; (5) the linear polyester obtained from o -hydroxytetradecanoic acid is heated at 270 DEG  C. under 1 mm. pressure with stannous chloride, producing monomer and a little dimer; the polymer of o -hydroxypentadecanoic acid lactone may be similarly treated.  A table gives the properties of the following additional products; monomeric and dimeric trimethylene, tetramethylene, pentamethylene, heptamethylene, and octamethylene succinates and ethylene azelate, dimeric ethylene succinate and phthalate, and monomeric nonamethylene, decamethylene, dodecamethylene, tridecamethylene and octadecamethylene succinates, decamethylene glutarate, hexamethylene adipate, triethylene glycol adipate, monomethylene adipate, heptamethylene suberate, tetramethylene and hexamethylene azelate, trimethylene, tetramethylene and pentamethylene sebacate, diethylene glycol sebacate, ethylene decamethylenedicarboxylate, ethylene brassylate and decamethylene octadecanedioate.  Additional starting materials for the preparation of the polyesters are oxalic, methylmalonic, dimethylsuccinic, cyclohexanedicarboxylic, phenylenediacetic, resorcinoldiacetic and hydroquinonediacetic acids, and b -b -dimethyltrimethylene glycol.  In examples of perfumes, ethylene brassylate, nonamethylene adipate, or hexamethylene azelate is added to: (a) an ambre perfume comprising labdanum, bergamot and rose; (b) a jasmin perfume comprising benzyl acetate, linalol, linalyl acetate and hydroxycitronellal; (c) a rose perfume comprising geraniol, citronellal and phenylethyl alcohol.ALSO:<PICT:0471914/III/1> Distillation apparatus consists of a vessel A, heated by the vapours of a liquid boiled in a vessel B, and fitted with a dephegmator E and a receiver D, the latter being connected to a vacuum pump.ALSO:Cyclic esters having rings of more than seven atoms, particularly those having rings of 15, 16 or 17 members, may be employed as perfume ingredients.  In examples, ethylene brassylate, nonamethylene adipate or hexamethylene azelate is added to (1) an ambre perfume comprising labdanum, bergamot and rose; (2) a jasmin perfume comprising benzyl acetate, linalol, linalyl acetate and hydroxycitronellal; (3) a rose perfume comprising geraniol, citronellal, and phenylethyl alcohol. Other cyclic esters specified are tetradecamethylene carbonate, decamethylene succinate and w-hydroxypentadecanoic lactone.