CS237293B1 - Processing of poly-functional initiators of polymerization - Google Patents

Description

The invention relates. a process for the preparation of lithium-containing polyfunctional polymerization initiators by reacting a divinylbenzene with an alkylaluminum lithium compound in hydrocarbon solvents.

It is known from DE-A-2 427 955 that polyfunctional polymerization initiators can be prepared by reacting o-, o- or p-divinylbenzene with moonoithium alkyls, in particular butyl alcohol in inert organic solvents.

Multifunctional soluble alkaloorganometallic initiators are required for the synthesis of star-branched polymers and for the preparation of end-functional polymers with a functionality greater than 2. According to the above DOS, the reaction of divinylbenzene with the organoalkalometallic compound must be carried out in large dilutions. The polyfunctional organoalkalocol compounds thus formed are more or less strongly branched or crosslinked to form microgels. Partially or completely intermolecularly crosslinked products may also be formed. These molecules are insoluble and therefore only conditionally useful as initiators for anionic polymorphs.

Soluble microgel crosslinked products can only be obtained according to NSR-DOS 2 427 955 if the concentration of divioylbenzene in the reaction mixture is below 2.5 wt. Even at this concentration range, the solubility of the initiators is a function of the ratio of divinylbenzene to molithium compound to be 0.5-1: 20: 1.

Sím. the greater the molar β-restriction of divinylbenzene to the low molecular weight organoalkal metal compound, the lower the divinylbenzene concentration in the reaction mixture must be, or? as the o-ratio increases, the number of bonds between the alkali

237 293 metal and carbon per molecule of reaction product whose molecular weight and degree of crosslinking increase.

PrcFo represents the molar ratio of divinylbenzene to the monoalkalometallic compound of 0.5: 1 lower limit. The upper limit is determined by the concentration of divinylbenzene in the reaction mixture. Above a certain cut-off ratio, at certain concentrations, some or all of the intermolecular cross-linking results in the formation of insoluble macrogels. For example, the upper limit of the molar ratio is for a 2.5% solution at 2: 1 and a 1.25% solution at 6.7: 1 ·

The prior art process has the following disadvantages, for which it is not suitable for the synthesis of initiators of anionic polymerization of monomers to low molecular weight telechelic polymers:

- since a low concentration of divinylbenzene is required, only low-concentration initiator solutions are also obtained,

- in order to synthesize polyfunctional organo-alkali metal initiators, an excess of divinylbenzene to the mono-alkali metal compound is in any case required so that all initiators are more or less cross-linked, which severely limits their solubility in hydrocarbon solvents,

the initiators themselves have a relatively high molecular weight, e.g. 2800, 265000 and 320000, so that they cannot be used for the synthesis of low molecular weight polymers.

These disadvantages are overcome by a process for preparing lithium-containing polyfunctional polymerization initiators by reacting a divinylbenzene with an alkyl monolithium compound in hydrocarbon solvents by reacting a solution of the divinylbenzene technical mixture consisting of 10 to 70 wt. 80 to 30 wt. 10% by weight of ethylstyrene and about 10% by weight of diethylbenzene, with an alkyl monolithium compound, in hydrocarbon solvents, over a period of 15 to 60 minutes at a temperature of 268 K to 303 K, optionally in the presence of a tertiary amine; , 1: 1 to 2: 1 and the molar ratio of lithium to tertiary amine is 1: 1 to 1: 1.5 ·

- 3 237 293

Preferably, secondary, iso- or n-butyllithium can be used as the alkyl lithium compound. Benzene or toluene can preferably be used as the hydrocarbon solvent. As the target amine, triethylamine, dimethylaniline or mixtures thereof can be advantageously used.

According to the process of the invention, soluble low molecular weight polyfunctional organolithium compounds are obtained at both low and high concentrations of divinylbenzene. The degree of metalation of the initiators is, depending on the molar ratio of the vinyl groups to the alkyllithium compound 2. The initiators of the invention are linear non-crosslinked and molecular organolithium compounds.

This eliminates the costly separation of divinylbenzene isomers from divinylbenzene technical mixtures and can be used directly to synthesize anionic soluble polyfunctional lithium initiators, wherein the solubility of the initiators is not a function of the divinylbenzene concentration.

Mixtures of divinylbenzenes, which are formed in the alkylation of benzenes and contain about 50 to 70 wt. % divinylbenzene, 20 to 40 wt. % ethylstyrene and about 10 wt. % diethylbenzene.

Example 1

In a 750 ml sulfonation flask equipped with a stirrer, thermometer, dropping funnel and argon inlet was placed 40 mmol of secondary butyllithium in 80 ml of benzene and 6 ml of triethylamine. 7.03 g of divinylbenzene technical mixture, which consisted of 57.2 wt. 7 divinylbenzene, 33 wt. % Of ethylstyrene and 9.8 wt. % diethylbenzene dissolved in 40 ml benzene. This mixture was added dropwise from the dropping funnel over 15 minutes. Thereafter, the mixture was stirred in the flask at 278 K for a further 2 hours.

237,293 functionalized with 44 mmol of ethylene oxide. After hydrolysis with water, removal of the aqueous phase and solvent removal on a vacuum rotary evaporator, the functionalized initiator was analytically investigated. It had an Eight-weighted average molecular weight of 920 and a hydroxyl group content of 7.8%, from which a functionality of 4.22 could be calculated.

Example 2

To 63 mmol of isobutyllithium dissolved in 100 ml of toluene was added dropwise 7.03 g of technical mixture of divinylbenzene from Example 1, dissolved in 40 ml of toluene. The reaction time was 30 minutes, the temperature was 298 K. After completion of the reaction, 76 mmol of ethylene oxide were functionalized and the product was worked up as in Example 1. The molar ratio of vinyl groups to butyllithium was 1.25 * -1, the average molecular weight of the functionalized initiator was 450. hydroxyl groups 8.5 wt. resulting in 2.25 functionality ·

Example 3

Example 1 was repeated with the difference that a technical mixture of divinylbenzene of 51.8 wt. % of divinylbenzene, 30.7 wt.% of ethylstyrene and 17.5 wt. % diethylbenzene. 40 mmol of n-butyllithium were used, and the average molecular weight of the functionalized initiator 850 was determined with 7.71 g of this technique in the vapor phase. The hydroxyl content was 884 wt. % and functionality 4.42.

Claims (4)

Object of the invention 237 293 A process for the preparation of polyfunctional polymerization initiators containing lithium by reacting a divinylbenzene with an alkylmmonium compound in hydrocarbon solvents, characterized in that a solution of a technical mixture of divinylbenzenes consisting of 10 to 70% by weight of divinylbenzene is reacted, 80 to 30% by weight of ethylstyrene and about 10% by weight of diethylbenzene, with the alkyl mono-lithium compound in hydrocarbon solvents over a period of 15 to 60 minutes at a temperature of 268 K to 303 K, optionally in the presence of a tertiary amine; alkyl lithium is 1.1: 1 to 2: 1 and the molar ratio of lithium to tertiary amine is 1: 1 to 1: 1.5 · 2. The process according to claim 1, wherein the compound used is secondary, iso- or o-butyllithium. 3. The process according to claim 1 or 2, wherein the hydrocarbon solvent is benzene or toluene. 0 * 4. A process according to any one of claims 1 to 3, wherein the target, amine, is triethylamine, dimethylamine or mixtures thereof.