DE4109236A1 - Cyclic carbonate ester prepn. - by transesterifying aliphatic hydroxy cpd. with di:aryl carbonate, tempering, and depolymerising prod. - Google Patents

Abstract

Esters of formula (I) (R1 = satd., opt. branched 3-18C hydrocarbon chain; n = 1 or 2) are prepd. by (1) reacting aliphatic hydroxy cpd. of formula HO-R1-OH (II) with diaryl carbonate of formula Ar1-OC(:O)-Ar2 (III) (Ar1, Ar2 = Ph, Ph substd. by alkyl, alkoxy, halogen or CN, or naphthyl) in presence of transesterification catalyst with splitting off of a phenol; (2) tempering; and (3) depolymerising. USE/ADVANTAGE - By insertion of tempering stage, (I) are obtd. in good yield and high purity, substantially free from cpds. with acidic H atoms, and can be used directly as monomers for anionic ring-opening polymerisation to form homo- and co-polymers with narrow mol.wt. distribution (DE3607627, 3700193, 3911557).

Description

The present invention relates to a method for Manufacture of cyclic carbonic acid esters by Implementation of the derived aliphatic hydroxyverbin with diaryl carbonates and subsequent depolyme risation, with an annealing phase before the depolymerization tion is inserted.

It is known cyclic carbonic acid esters from alipha table diols by condensation with various Carbonic acid derivatives, such as phosgene, dialkyl carbonates or to produce diaryl carbonates. Thereby fall next to considerable amounts of the desired ring carbonates open-chain oligomeric or polymeric carbonates, with the tendency to form rings in the five-membered Cyclocarbonates is still largest and towards larger rings decreases sharply (Houben-Weyl, Methods der Organic Chemistry, 4th ed., Vol. E4, pp. 83 ff., Thieme Verlag, Stuttgart, 1983).  

For better yields even with 6 and higher links Ring carbonates are obtained through a so-called De Polymerization process being the one in the primary step formed polymers or oligomers to a large Part converted into cyclic monomers or oligomers will. In J. Am. Chem. Soc. 52, 314 (1930); J. Am. Chem. Soc. 55, 5031 (1933) are for this purpose in essential basic catalysts, e.g. B. as metal added sodium called, while in DE-OS 31 03 135, 31 03 136, 31 03 139, 31 03 140 and 32 04 078 it becomes clear that yields and purity of the products can be increased if one before the depolymerization those necessary for the production of the primary condensates removed basic catalysts. The separation of the Catalysts and other foreign substances from the viscous However, polycarbonate precursors are technically related moderately complex and therefore not very economical. It was which is why procedures were developed in which before the De polymerization stage ent the basic catalysts neither neutralized (DE-OS 34 18 092) or from the front in amounts of less than 0.03% by weight based on the diol component can be used (DE-OS 34 18 091).

The depolymerization is neutral here with the help gating catalysts performed. You get that too 6- and higher-membered aliphatic ring carbonates in good yields and high purity, but not for all applications are sufficient. For example, for the anionic ring opening polymerization of 6- and higher-membered cyclocarbonates to homo-, and (block) co  polymers, as in DE-OS 36 07 625, DE-OS 36 07 627, DE-OS 37 00 193 and DE-OS 39 11 557 described, high pure, hydroxyl-free starting monomers are required, otherwise by deactivating the initiator either no or only a non-reproducible polymerization entry.

The one required for "anionic polymerizations" Purity of the cyclocarbonates can be known with the so far only by a special, subsequent procedure teten cleaning step, z. B. recrystallization achieved what is technically complex and expensive. target the present application was therefore a simple syn thesis process that the cyclic carbonic acid ester in as simply as possible directly in an "anio African polymerisation "deliver sufficient quality can.

It now became a multi-stage one-pot process position of aliphatic ring carbonates of the formula (I) found

wherein

R¹ for a saturated, straight-chain or branched hydrocarbon chain with 3 to 18 carbon atoms and
n represents 1 or 2,

by reaction of aliphatic hydroxy compounds Formula (II)

HO-R¹-OH (II)

wherein R 1 has the same meaning as in formula (I),

with diaryl carbonates of the formula (III)

wherein Ar¹ and Ar² are independently phenyl; Alkyl, Alkoxy, halogen or cyano substituted Is phenyl or naphthyl,

with the elimination of phenols and subsequent depoly merization, with transesterification catalysts such. B. from the Range of tin, titanium and zirconium compounds as well Alkali hydroxides in small amounts, as in DE-OS 34 18 092 described, used, thereby ge indicates that between the reaction of the alcohols Formula (II) with the diaryl carbonates of the formula (III) and the depolymerization stage an annealing phase (Intermediate treatment), preferably using a weak inert gas flow, is inserted.

In this way one obtains highly pure, for the "anio African ring opening polymerization "without further Products that can be used for cleaning in high yields. It is advantageous in the method according to the invention furthermore that there is no need to change the catalyst, d. H. Condensation and depolymerization can take place with the same catalyst.

Aliphatic ring carbonates that can be produced according to the invention of the formula (I) are, for example, 1,3-dioxan-2-one, as well as substituted 1,3-dioxan-2-ones such as 5-methyl-1,3- dioxan-2-one, 5-ethyl-1,3-dioxan-2-one, 5,5-dimethyl-1,3- dioxan-2-one, 5,5-diethyl-1,3-dioxan-2-one, 5-ethyl-5- methyl-1,3-dioxan-2-one, 5-methyl-5-propyl-1,3-dioxan-2- on and 5-butyl-5-methylpropan-1,3-dioxan-2-one, penta methylene carbonate, hexamethylene carbonate and bishexa methylene biscarbonate, the dimeric hexamethylene carbonate and Dodecamethylene carbonate.  

Aliphatic ring carbonates that can be produced are preferred those of formula (IV)

wherein R² and R³ are independently hydrogen or C₁-C₄ alkyl.

1,3-Dioxan-2-one, 5-methyl-1,3- dioxan-2-one, 5-ethyl-1,3-dioxan-2-one, 5,5-dimethyl-1,3- dioxan-2-one, 5,5-diethyl-1,3-dioxan-2-one, 5-methyl-5- propyl-1,3-dioxan-2-one and 5-butyl-5-methyl-1,3-dioxane Called 2-one.

Aliphatic ring car that can be produced with particular preference Bonat is 5,5-dimethyl-1,3-dioxan-2-one (neopentyl glycol carbonate).

Alcohols of the formula (II) which can be used according to the invention are, for example, propane-1,3-diol, and substituted Propane-1,3-diols such as 2-methylpropane-1,3-diol, 2-ethyl propane-1,3-diol, 2,2-dimethylpropane-1,3-diol, 2,2-di  ethylpropane-1,3-diol, 2-ethyl-2-methylpropane-1,3-diol, 2-methyl-2-propylpropane-1,3-diol and 2-methyl-2-butyl propane-1,3-diol, pentane-1,5-diol, hexane-1,6-diol, 2,2,5- Trimethylhexane-1,6-diol, octane-1,8-diol, decane-1,10- diol, and dodecane-1,12-diol.

Alcohols of the formula (II) which can preferably be used are Ver compounds of formula (V)

wherein R⁴ and R⁵ independently of one another are hydrogen or C₁-C₄- Are alkyl, for example 2,2-dimethylpropane 1,3-diol, 2,2-diethylpropane-1,3-diol, 2-methyl-2-propylpropane-1,3-diol and 2-butyl 2-methylpropane-1,3-diol.

Alcohol which can be used with particular preference is 2,2-di methylpropane-1,3-diol.

In formula (III) Ar ¹ and Ar ^{2 are} preferably independently phenyl; C ₁ -C ₄ alkyl, C ₁ -C ₄ alkoxy, halogen or cyano substituted phenyl or naphthyl.

Examples of diaryl carbonates of the formula (III) are to call wise; Diphenyl carbonate, the isomeric Di cresyl, bis (chlorophenyl) -, bis (bromophenyl) -, bis (cyano  phenyl) and bis (methoxyphenyl) carbonates, cresylphenyl carbonates, chlorophenylphenylcarbonates, bromophenyl phenyl carbonates, cyanophenyl phenyl carbonates, methoxy phenylphenyl carbonates, di-1-naphthyl and di-2-naphthyl carbonate. Diphenyl is particularly preferably used carbonate.

Catalysts which can be used according to the invention are at to name, for example, alkali and alkaline earth hydroxides, such as potassium, sodium and calcium hydroxide in amounts of less than 0.03% by weight, based on the diol component, also dialkyltin oxides, such as dibutyltin oxide and di octyltin oxide, dialkyltin dicarboxylates such as dibutyl tin dilaurate and dioctyl tin dilaurate, tin tetraalkoxides, Tin (II) compounds, such as tin (II) acetate, tin (II) laurate, elemental tin, preferably in finely divided form, Monoalkyltin compounds such as butylstannonic acid, octyl stannic acid, butyltin trimethanolate and butyltin triisooctylate, titanium esters, such as titanium tetraethylate, Titanium tetraisopropylate, titanium tetrabutylate, titanium tetra isobutylate and titanium tetradodecylate, zirconium esters, such as Zirconium tetraethylate and zirconium acetylacetonate, as well as lead (II) acetate.

Catalysts which can be used with preference are organotin tins compounds of formula (VI)

R _y ⁶Sn (OR⁷) _4-y (VI)

wherein

y represents an integer between 1 and 3,
R⁶ or R⁷ are each an alkyl group with 1-12 C atoms or an aryl radical with 6-14 C atoms or
R⁷ alone is to be a residue of an aliphatic carboxylic acid with 2-18 C atoms,

or tin compounds of the formulas (VII) - (IX)

(R) ₂SnO (VII)

(R) ₃SnOSn (R) ₃ (VIII)

RSn (O) OH (IX)

wherein R is an alkyl group with 1-12 carbon atoms to interpret. Examples include: butyl and oc tylstannonic acid, dibutyl and dioctyltin oxide, dibutyl and dioctyltin dilaurate, butyltin triisooctylate, butyl tin triisooctonoate, butyltin trimethylate and bistri butyltin oxide.

The quantities used for the transesterification catalysts mentioned gates are generally 2 to 0.001 wt .-%, and in the case of basic catalysts at 0.03 to 0.0005 % By weight based on the hydroxy component and preferred at 0.5 to 0.05% by weight, or with basic catalysts goals at 0.01 to 0.005 wt .-% based on the hydroxy component.  

The diaryl carbonates of formula (III) are preferred in amounts of 1.2 to 0.8 moles per mole of aliphatic Hy droxy compound of the formulas (II) used. Especially preference is given to using as equimolar men as possible gene on diaryl carbonate (III) and hydroxy compound (II).

In the synthetic process according to the invention, first of all the aliphatic hydroxy compounds of the formula (II) with the diaryl carbonates of the formula (III) under Abspal tion of the derived phenols implemented. The he for this required reaction temperatures are generally NEN in the range of 80 and 300 ° C and preferably between 100 and 250 ° C, depending on the volatile speed of the phenol to be separated expediently in a pressure range of 1 bar to 0.1 mbar and preferred at a pressure of 200 mbar to 1 mbar. It is advisable to use a column, the one clean separation of the reaction phenol from the starting materials enables. The diols remain in the reaction flask. Man receives almost quantitative yields of phenol, wel ches high purities of at least 98% and preferred <99.5% and directly for many applications can be used.

The first reaction stage is the one according to the invention annealing phase to be carried out. Doing so the remaining reaction mixture 0.5 to 20 h and be preferably for 1 to 10 hours at a temperature of 100 to 300 ° C and preferably from 150 to 250 ° C and a pressure from 1 bar to 20 mbar, preferably from 750 mbar to  50 mbar and particularly preferably from 500 mbar to Kept 100 mbar, with no cyclic carbonic acid ester is discharged from the reaction vessel. These Measure can preferably be carried out by passing a gas through be carried out through the reaction flask, wherein inert gases such as nitrogen, carbon dioxide and / or Noble gases are preferred. The reaction area conditions and in particular the temperature, the pressure and the amount of inert gas is coordinated so that if possible no cyclic carbonic acid formed ester passes during the tempering phase. It will be there at the specified temperatures and pressures, for example as inert gas flows from 0.05 to 5 l / h, preferably from 0.1 to 2 l / h and particularly preferably from 0.1 to 1 l / h based on mole of diol component used.

The subsequent depolymerization takes place with the The catalyst used either by another Increase the temperature or decrease the pressure. A suitable temperature range is between 120 and 300 ° C and particularly preferably between 150 and 250 ° C. You work depending on the volatility of yourself forming ring carbonates favorably at a pressure between 0.001 to 200 mbar, preferably 0.01 to 150 mbar, particularly preferably at a pressure between 0.01 and 80 mbar and very particularly preferably between 0.1 and 50 mbar. The removal of the ring carbonates the reaction vessel can of course also with With the help of an inert gas e.g. B. nitrogen, carbon dioxide and / or noble gases are carried out.  

The cyclic carbonic acid esters of the formula obtained (I) and (IV) are produced in high yields (<85% of the Theory) and are very pure and essentially free of Compounds with acidic hydrogen atoms so that they directly as monomers for without further cleaning measures the "anionic ring opening polymerization" for the manufacture development of homo- and copolymers with narrow molecular weights distribution (cf. DE-OS 36 07 625, DE-OS 36 07 627, DE-OS 37 00 193 and DE-OS 39 11 557) are used can.

Example 1

5,5-dimethyl-1,3-dioxan-2-one (neopentyl glycol carbonate) A mixture of 1.46 kg (14.0 mol) of 2,2-dimethyl-1,3- propanediol (neopentyl glycol), 3.00 kg (14.0 mol) di phenyl carbonate and 730 mg dibutyltin dilaurate (DBTL) is in a 6 l stirrer with column (1.2 m, ge fills with glass Raschig rings). In doing so at a bottom temperature of initially 110 ° C, the increased with reaction to 190 ° C, and a pressure of 30-20 mbar 2.62 kg (99.4% of theory) of phenol with a boiling point of 90-82 ° C and a purity of <99.9 (GC area% gas chromatography area percentages) distilled off. It was then at a swamp for 18 hours temperature of 195-210 ° C under a pressure of 300-450 mbar 3 l / h nitrogen through the bottom flask tet. After switching off the embroidery current and lowering the Pressures to 20-25 mbar went at an internal temperature from 175 to 206 ° C initially 111 g (7% of theory) Product with a boiling point of 151-156 ° C and a purity of 98.9 (GC area%), which in a subsequent approach can be used again, and then 1.53 kg (87% of theory) pure product with boiling point 157.5-158 ° C, a melting point of 110-111 ° C and a GC Purity of 99.5 (GC area%) over.  

Example 2

Analogously to Example 1, 937 g (9.00 mol) of 2,2-di methylpropane-1,3-diol (neopentyl glycol), 1.93 kg (9.00 mol) diphenyl carbonate and 470 mg dibutyltin oxide implemented and 1.69 kg (99.7% of theory) phenol distilled off with a purity of 98.5 (GC area%).

The subsequent tempering was 4 h at 200-205 ° C and a pressure of 500 to 400 mbar with transfer of 4 l / h of dry nitrogen. Subsequently was at a bottom temperature of 180-200 ° C and a Pressure of 20-25 mbar initially 59.5 g (5.7% of theory) per product with a boiling point of 105-158 ° C (GC purity 93.4 area%), which in a subsequent approach again and finally 999 g (86.0% d.Th). Pure product with a boiling point of 157-158 ° C, a melting point of 110-111 ° C and a purity of 99.9 (GC area%) distilled off.

Example 3

Analogously to Example 1, 937 g (9.00 mol) of 2,2- Dimethylpropane-1,3-diol (neopentyl glycol), 1.93 kg (9.00 mol) diphenyl carbonate and 470 mg butylstannon acid converted and 1.68 kg (99.2% of theory) phenol distilled off with a purity of 99.8 (GC area%). The subsequent annealing was at 4.5 hours 195-205 ° C and a pressure of 500 to 400 mbar under pressure conducted from 4 l / h of dry nitrogen. On were concluded at a bottom temperature of  180-220 ° C and a pressure of 20-25 mbar 1.02 kg (93% i.e.) pure product with a boiling point of 156-157 ° C, a melting point of 110-111 ° C and a purity of 99.5 (GC area%) distilled off.

Example 4 (for comparison) / without tempering phase

A mixture of 781 g (7.50 mol) of 2,2-dimethylpropane 1,3-diol, 1.61 kg (7.50 mol) diphenyl carbonate and 400 mg Dibutyltin dilaurate was converted analogously to Example 1 sets and thereby 1.35 kg (96% of theory) phenol with a Purity of 99.9 (GC area%) distilled off. The on closing depolymerization took place at 195-220 ° C and 25-30 mbar pressure and delivered 935.5 g (96% of theory) 5.5- Dimethyl-1,3-dioxan-2-one with a melting point of 93-104 ° C and a purity of 95 (GC area%).

Example 5 (for comparison) / without tempering phase

A mixture of 312 g (3.00 mol) of 2,2-dimethylpropane 1,3-diol, 643 g (3.00 mol) and 16 mg of powdered Ka Lithium hydroxide (0.005% by weight) was analogous to the example 1 reacted and 529 g (94% of theory) of phenol distilled. The subsequent depolymerization took place with the addition of 160 mg of titanium tetradodecylate 190-230 ° C and 20-25 mbar pressure and delivered 247 g (63% i.e.) 5,5-dimethyl-1,3-dioxan-2-one with a melt point of 87-91 ° C.  

Anionic polymerization of neopentyl glycol carbonates General rule

To a 12.5% by weight solution of crude neopentylgly Colcarbonates from Examples 1-5 in dry Toluene was in each case at 15 ° C under nitrogen Solution of sec-butyllithium in cyclohexane. The Reaction solution was 60 minutes in all cases Leave at 15 ° C and by adding a 50 percent methanolic phosphoric acid solution deactivated. The Working up was carried out by precipitation in methanol, fil tration and drying. Initiator amount, expected and obtained molecular weight and yields, see Table.  

table

Results of the "anionic" ring opening polymerization of neopentyl glycol carbonates

From the results of the experiments on "anionic ring opening polymerization "clearly shows that the neopentyl glycol not according to the invention carbonates are only undefined to oligomeric alipha table carbonate polymerize, d. H. open visible disturbing impurities the growing oil Abort the monomer chain prematurely.

Claims (8)

1. Process for the preparation of cyclic carbonic acid esters of the formula (I) wherein
R¹ for a saturated, straight-chain or branched hydrocarbon chain with 3 to 18 carbon atoms and
n represents 1 or 2,
by reaction of aliphatic hydroxy compounds of the formula (II) HO-R¹-OH (II) in which R¹ has the same meaning as in formula (I),
with diaryl carbonates of the formula (III) wherein Ar¹ and Ar² represent independently phenol, alkyl, alkoxy, halogen or cyano-substituted phenyl or naphthyl, wherein in the presence of transesterification catalysts with elimination of phenols and subsequent depolymerization, characterized in that between the reaction of the alcohols of formula (II ) with the diaryl carbonates of the formula (III) and the depolymerization stage, an annealing phase is inserted. 2. The method according to claim 1, characterized in that that the tempering phase at a temperature of 100 to 300 ° C and a pressure of 1 bar to 20 mbar is carried out. 3. The method according to claim 1, characterized in that the tempering phase at a temperature of 150 to 250 ° C is carried out. 4. The method according to claim 1, characterized in that the tempering phase at a pressure of 750 mbar up to 50 mbar. 5. The method according to claim 1, characterized in that the tempering phase at a pressure of 500 mbar up to 100 mbar.   6. The method according to claim 1, characterized in that that the tempering phase using a Inert gas flow is carried out. 7. The method according to claim 1, characterized in that that no cyclic during the tempering phase Carbonic acid esters discharged from the reaction vessel becomes. 8. Process for the preparation of cyclic carbonic acid esters of the formula (IV) wherein R² and R³ are independently hydrogen or C₁-C₄ alkyl,
by reaction of aliphatic hydroxy compounds of the formula wherein R⁴ and R⁵ are independently hydrogen or C₁-C₄-, according to claim 1.