| 摘要 |
<p>#CMT# #/CMT# Preparing a mixture from [1,4]dioxane-2,5-dione compounds (Ia)-(Ic), comprises reacting alpha -hydroxycarboxylic acid compounds (IIa) and/or (IIb), complete stereoisomerically pure compound of (Ia)-(Ic) or a mixture of two or three compounds of (Ia)-(Ic) or an oligomer or polymer of hydroxycarboxylic acid compound (III), with a catalyst or a mixture of at least two catalysts. #CMT# : #/CMT# Preparation of a mixture from [1,4]dioxane-2,5-dione compounds of formulae (Ia)-(Ic), comprises reacting alpha -hydroxycarboxylic acid compounds of formulae (IIa) and/or (IIb), complete stereoisomerically pure compound of (Ia)-(Ic) or a mixture of two or three compounds of (Ia)-(Ic), or an oligomer or polymer of hydroxycarboxylic acid compound of formula (III), with a catalyst or a mixture of at least two catalyst. R : 1-6C-alkyl; and n : 1-50. #CMT#[Image]#/CMT# #CMT#[Image]#/CMT# #CMT#USE : #/CMT# The mixture is useful for the preparation of amorphous polylactide, preferably for the preparation of stereocomplexes of polylactic acid and/or stereo-block-copolymers of lactic acid, which is dilactides of lactic acid, D,D-dilactide and L,L-dilactide (claimed). #CMT#ADVANTAGE : #/CMT# The mixture obtained from the process exhibits high thermal stability. #CMT#ORGANIC CHEMISTRY : #/CMT# Preferred Process: The process takes place at 80-300[deg] C, preferably 120-160[deg] C for 1 minute to 48 hours, preferably 0.5-4 hours. The process comprises at least purifying the mixture obtained by the reaction of (Ia)-(Ic), where the ratio of the sum of (Ia) and (Ib) to (Ic) is increased to at least 10:1, preferably 1000:1, and completely removing (Ic). The purification step is filtration, washing, distillation, crystallization and/or recrystallization of the mixture of (Ia)-(Ic). The crystallization and/or recrystallization are carried out from a melt or solvent, where the solvent is alcohol, ester, ketone or hydrocarbon, preferably acetone, isopropanol, ethyl acetate and/or toluene. The preparation of an equimolar mixture of both enantiomers of dilactides of lactic acid, D,D-dilactide and L, L-dilactide comprises reacting levorotatory L(-)-lactic acid with trioctylamine to obtain trioctyl ammonium lactate, distilling trioctyl ammonium lactate in the presence of a catalyst to obtain a fractional group, which is added to enantiomers containing dilactide of lactic acid, D,D-dilactide and L,L-dilactide, and not D,L-lactide, and recrystallizing the fractional group with acetone to obtain pale crystals with a melting point of 112-119[deg] C, which are added to equimolar D,D-dilactide and L,L-dilactide. Preferred Components: The catalyst is a metal component from: (a) 1-14 group elements, preferably metal salt and/or metal organic compounds, alkoxide, oxide, salts of organic acids, further preferably metal salt and/or metal organic compounds of sodium, potassium, magnesium, calcium, iron, titanium, zinc, tin, lead, or its oxide, hydroxide, carbonate, benzoate, lactate or octoate, preferably magnesium oxide, calcium oxide, potassium carbonate, sodium lactate, potassium benzoate, tin octoate, dibutyltin oxide, dibutyltin oxide of formula (BuSnOc 3) or tin oxide; and/or (b) nitrogen containing or phosphorus containing organic compounds, which are primary, secondary and/or tertiary amine and/or aliphatic, aromatic N-hetero-cyclic compounds with 5-7 ring atoms or phosphine, preferably triethylamine, ethyldiisopropylamine, dibutylamine, tributylamine, trioctylamine, dicyclohexylamine, 4-(N,N-dimethyl)-aminopyridine, 2,2,6,6-tetramethylpiperidine, 1,2,2,6,6-pentamethylpiperidine and/or tributylphosphine. The weight ratio of the catalyst with respect to (IIa) and/or (IIb), (Ia)-(Ic) or a mixture of two or three above compounds, or (III) is 1:1-1:10000, preferably 1:100-1:1000. The molar ratio between (Ia) and (Ib) is 1:2-2:1, preferably 1:1. The molar ratio of the sum of (Ia) and (Ib) to (Ic) is 10:1-1:1, preferably 10:1-2:1. (IIa) or (IIb) is enantiomerically pure. #CMT#EXAMPLE : #/CMT# Trioctylamine and L-lactic acid with an optical purity of 99% were heated to obtain trioctylammonium lactate. The obtained mixture was distilled. Further dibutyltin oxide (1 wt.%) was added and heated at 250[deg] C to obtain two fractional group at a distillation temperature of 140-165[deg] C. In the progress of the distillation, an aqueous clear yellow fluid was obtained. The obtained liquid was cooled and acetone was added to form pale crystal comprising 50 wt.% of D,D-dilactide and L,L-dilactide of lactic acid and with a melting point of 112-119[deg] C.</p> |
