Trialkylsilyloxy-1,1-disphenyl-ethylenes and polymers prepared therewith.

The invention relates to trialkylsilyloxy-1,1-diphenylethylenes of the general formula I and new polymers produced therewith with aryl trialkylsilyl ether or phenolic hydroxyl end groups and a process for the preparation of these polymers by anionic polymerization.<chemistry id="chem0001" num="0001"><img file="EP0348744A2_D0001.tif" /></chemistry> wherein R¹, R² = H, C₁-C₄-alkyl, OCH₃ R³ = H, C₁-C₄-alkyl, O-C₁-C₄-alkyl, R⁴ = H, C₁-C₄ alkyl, R⁵ = C₁-C₄ alkyl, R⁶ = C₁-C₄ alkyl.

DE-OS P 37 25 848 describes the preparation of polymeric dihydroxy compounds by anionic polymerization of suitable compounds, possibly reducing the reactivity of the polyanion by 1,1-diphenylethylene, reaction with 2,5-dimethoxybenzyl bromide and removal of the protective group by subsequent ether cleavage with trimethyliodosilane, Trimethylchlorosilane and sodium iodide or acids.

The compounds are suitable as stabilizers for polymers, in particular those with unsaturated bonds in the polymer chain, against thermal, radiation-induced and oxidative degradation.

The reaction of so-called "living" polymers (such as polystyryllithium) with halogen compounds containing further functional groups provides functional polymers, but is accompanied by a number of side reactions (cf. J. Polym. Sci. <u style="single">A 3</u>, 4131 (1965); polymer<u style="single">17</u>, 1976, 1020; J. Polym. Sci.<u style="single">B 14</u>, 471 (1976; Adv. Polym. Sci. <u style="single">56</u>, 72 (1984)). The yield of functional polymer is therefore often unsatisfactory. This reaction is therefore unsuitable for technical purposes.

The invention relates to trialkylsilyloxy-1,1-diphenylethylenes of the formula (I), polymers prepared therefrom with aryl trialkylsilyl ether end groups or phenolic hydroxyl end groups of the formulas (II) and (III) and corresponding preparation processes.<chemistry id="chem0002" num="0002"><img file="EP0348744A2_D0002.tif" /></chemistry> in which A = polymer of anionically polymerizable vinyl compounds, R¹, R² = H, C₁-C₄-alkyl, OCH₃, R³ = H, C₁-C₄-alkyl, O-C₁-C₄-alkyl, R⁴ = H, C₁-C₄ alkyl, R⁵ = C₁-C₄ alkyl, R⁶ = H, C₁-C₄ alkyl R⁷ = H, Si (R⁵) ₃.

The trialkylsilyloxy-1,1-diphenylethylenes of the formula I according to the invention can be prepared by processes known per se. Alkali-catalyzed thermal cleavage of 1-alkyl-1-phenyl-bis (hydroxyphenyl) methane of the formula (IV) gives hydroxy-1,1-diphenylethylenes of the formula (V) (DE-AS 1 235 894):<chemistry id="chem0003" num="0003"><img file="EP0348744A2_D0003.tif" /></chemistry> where in formula IV and V R¹, R², R³, R⁴, R⁶ have the meaning given above.

The trialkylsilyloxy-1,1-diphenylethylenes (I) are formed by reacting the hydroxydiphenylethylenes of the formula (V) with halosilanes of the formula (VI) in the presence of acid scavengers.<chemistry id="chem0004" num="0004"><img file="EP0348744A2_D0004.tif" /></chemistry> Hal = Cl, Br.

The starting product for the preparation of the compounds of the formula (I) according to the invention are 1-alkyl-1-phenyl-bis (hydroxyphenyl) methanes of the formula (IV), in which the substituents R¹ to R⁶ have the meaning given above.

Examples of compounds of the formula IV are: 1-methyl-1-phenyl-bis (4-hydroxyphenyl) methane, 1-ethyl-1-phenyl-bis (4-hydroxyphenyl) methane, 1-propyl-1-phenyl-bis (4-hydroxyphenyl) methane, 1-pentyl-1-phenyl-bis (4-hydroxyphenyl) methane, 1-methyl-1- (4-methylphenyl) bis (4-hydroxyphenyl) methane, 1-methyl-1- (4-methoxyphenyl) bis (4-hydroxyphenyl) methane, 1-methyl-1- (3,5-dimethylphenyl) bis (4-hydroxyphenyl) methane, 1-methyl-1-phenyl-bis (2-hydroxy-phenyl) methane, 1-methyl-1-phenyl - [(4-hydroxyphenyl) - (2′-hydroxyphenyl)] methane, 1-methyl-1-phenyl-bis (3-methyl-4-hydroxyphenyl) methane, 1-methyl-1-phenyl-bis (3-methoxy-4-hydroxyphenyl) methane, 1-methyl-1-phenyl-bis (3,5-dimethyl-4-hydroxyphenyl) methane, 1-methyl-1-phenyl-bis (3,5-dimethyl-2-hydroxyphenyl) methane.

Preferred compounds of formula (IV) are those with the substituents R¹ = H, R² = H, CH₃, OCH₃, R³ = H, CH₃, OCH₃, R⁴ = H, CH₃, R⁶ = H, CH₃. R¹, R², R³, R⁴, R⁶ is particularly preferably hydrogen.

The compounds of the formula (IV) can be cleaved under the conditions specified in DE-AS 1 235 894. Suitable halosilanes for the reaction of the compounds of the formula (V) to the trialkylsilyloxy-1,1-diphenylethylenes of the formula (I) according to the invention correspond to the formula (VI).

Examples of halosilanes of the formula VI are: Trimethylchlorosilane, triethylbromosilane, tripropylchlorosilane, diethylmethylchlorosilane. Trimethylchlorosilane and triethylchlorosilane are preferred, and trimethylchlorosilane is particularly preferred.

Compounds of the formula (V) and compounds of the formula (VI) can generally be used in a molar ratio of 1: 1 (or with a slight excess of (VI)) in inert solvents, such as hydrocarbons (petrol, ligroin, heptane, pentane, cyclohexane, benzene, Toluene, xylene), halogenated hydrocarbons (chloroform, methylene chloride, dichloroethane, chlorobenzene) or ethers (diethyl ether, diisopropyl ether, dibutyl ether); hydrocarbons and the presence of a base such as ammonia, triethylamine, tributylamine, pyridine, N-methylimidazole, quinoline are preferred. But you can also convert the compound of formula (V) into a salt and implement this in dry form with the halosilane. In addition to the amine salts mentioned above, suitable salts are also those of lithium, sodium and potassium.

The reaction temperature is 0 to 120 ° C, preferably 10 to 100 ° C.

The base must be used in a slight excess in at least a stoichiometric amount based on (V).

After the salts formed in the reaction have been separated off, for example by filtration, the compounds of the formula (I) can be used directly. Additional purification is possible by distillation.

Suitable compounds of the formula I for the preparation of the new polymers are, for example: 4-methyl-4'-trimethylsilyloxy-1,1-diphenylethylene, 4-ethyl-4'-triethylsilyloxy-1,1-diphenylethylene, 3-methoxy-4'-trimethylsilyloxy-1,1-diphenylethylene, 4-isopropyl-4'-triethylsilyloxy-1,1-diphenylethylene, 4-methyl-2'-trimethylsilyloxy-5'-methyl-1,1-diphenylethylene, 3-methyl-4'-trimethylsilyloxy-1,1-diphenylethylene, 4-methoxy-2′-trimethylsilyloxy-3 ′, 5′-dimethyl-1,1-diphenylethylene, 3-methoxy-4-trimethylsilyloxy-1,1-diphenylethylene, 4-trimethylsilyloxy-β-methyl-1,1-diphenylethylene, 4-trimethylsilyloxy-β-propyl-1,1-diphenylethylene, particularly preferred 4-trimethylsilyloxy-1,1-diphenylethylene.

The process according to the invention for the preparation of the polymeric compounds having aryl trimethylsilyl ether end groups or the polymeric compounds having phenolic hydroxyl end groups according to formulas (II) and (III) requires the following steps:<ul id="ul0001" list-style="none"><li>1. Preparation of a polyanion by anionic polymerization of a suitable vinyl compound.</li><li>2nd Reaction of the polyanion with a compound of the formula (I)<chemistry id="chem0005" num="0005"><img file="EP0348744A2_D0005.tif" /></chemistry> where R¹ to R⁶ have the meaning given above.</li><li>3rd Neutralization of the reaction products (which are themselves polyanions) with protic compounds to form the polymeric compounds with aryltrisilyloxy ether end groups according to formulas (II) and (III) with R⁷ = Si (R⁵) ₃ and optionally</li><li>4th Silyl ether cleavage for the preparation of the polymeric compounds with phenolic hydroxyl end groups according to formula (II) and (III) with R mit = H.</li></ul>

In step 1, anionically polymerizable vinyl compounds are polymerized in aromatic or aliphatic hydrocarbons or an ether with an alkylalkali metal, arylalkali metal compound or an oligomeric α-methylstyrene-alkali metal compound to form a "living" polyanion or polydianion until the monomer is completely converted. In step 2, this is reacted with compounds of the formula (I), a new polyanion or dianion being formed. In step 3, the polyanion or dianion is neutralized with protic compounds and the polymer (II) or (III) isolated with aryltrisilyloxy ether end groups (R⁷ = Si (R⁵) ₃).

To prepare the polymers (II) or (III) with phenolic hydroxyl end groups (R⁷ = H), the polyanion or dianion is neutralized in step 3 after steps 1 and 2, the product is isolated if necessary and the silyl ether is cleaved.

Suitable anionically polymerizable compounds for the purposes of the invention are, for example, styrene, p-methylstyrene, vinylpyridine, vinylnaphthalene, isopropenylnaphthalene, 1,3-butadiene, isoprene or mixtures thereof. Styrene, 1,3-butadiene, isoprene or mixtures of styrene / 1,3-butadiene and styrene / isoprene are preferred.

Suitable aromatic and aliphatic hydrocarbons for the purposes of the invention are, for example, toluene, benzene, xylene, pentane, hexane, cyclohexane. Ethers in the sense of the invention are, for example, tetrahydrofuran and dioxane. A mixture of aromatic or aliphatic hydrocarbons and ethers can also be used to set certain reaction rates.

For the preparation of the polymers according to formula (II), alkyl alkali metal compounds, in particular n-butyl or sec-butyllithium, are preferably used as initiators.

Arylalkali metal compounds, in particular naphthalene sodium, naphthalene potassium, oligo-α-methylstyryl sodium or oligo-α-methylstyryl potassium or 1,3-phenylene-bis (3-methyl-1-phenylpentylidene) bis are preferably used to prepare the polymer of the formula (III) (lithium) used as initiators.

The anionically polymerizable compounds can be polymerized at -100 ° C to + 80 ° C, preferably -78 ° C to + 50 ° C.

The "living" polymer anions can be reacted with the compound (I) at -78 ° C to + 100 ° C, preferably at 0 ° C to + 50 ° C. Compound (I) is preferably used in excess, based on the initiator.

Suitable neutralizing agents for the "living" polymer anions are, for example, weak inorganic or organic acids, in particular methanol or acetic acid.

Since the process according to the invention works with "living" carbanions, conditions must of course be observed under which "living" carbanions are stable, eg inert atmosphere, exclusion of atmospheric oxygen and moisture.

The silyl ethers of the formulas (II) and (III) (R⁷ = Si (R⁵) ₃ can preferably be cleaved by acidifying their solutions with inorganic acids (for example hydrochloric acid) or organic acids (for example p-toluenesulfonic acid). The cleavage is carried out in the temperature range from room temperature to the boiling point of the solvent.

The polymers of the formulas (II) and (III) (R⁷ = H) according to the invention can be isolated by precipitation of the polymer from the solution, preferably using methanol, or by evaporation of the polymer solution in known evaporation units.

The polymers according to formulas (II) and (III) according to the invention have (particularly controllable via the ratio of monomer concentration to initiator concentration) molecular weights of 500 g / mol to 500,000 g / mol, preferably 1,000 g / mol to 250,000 g / mol 1,000 g / mol to 100,000 g / mol.

The polymers of the formulas (II) and (III) according to the invention are suitable as stabilizers and / or lubricants for synthetic polymers. They can also be used (R⁷ = H) to build up polycondensates.

Examples

1.1 Preparation of 1-methyl-1-phenyl-bis (4-hydroxyphenyl) methane

HCl gas is passed into a mixture of 240 g (2 mol) acetophenone, 940 g (10 mol) phenol and 30 g mercaptopropionic acid until saturation is reached, slowly warming to 50 ° C. The mixture is left under these conditions for 5 hours, left to stand overnight and first HCl and water are distilled off under water pump vacuum and then the excess phenol is removed to a bottom temperature of 120 ° C. The remaining residue of 510 g is redissolved from 1250 ml of toluene under reflux, suction filtered after drying and dried: 412 g mp 185-7 ° C ds 72% of theory (MG 580).

1.2 Preparation of 4-hydroxy-1,1-diphenylethylene

400 g of the triphenylmethane derivative obtained by the above process are brought to 180-220 ° C. with 4 g of NaOH. At 130 - 160 ° C and about 15 mbar, the fission products pass over. A total of 340 g of distillate and about 56 g of a brown resinous residue are obtained.

A fraction of 120 g which corresponds to the title compound (45% of theory; MW 196) is isolated from this distillate by redistillation.

1.3 Preparation of 4-trimethylsilyloxy-1,1-diphenylethylene

100 g (0.51 M) of the 4-hydroxy-1,1-diphenylethylene obtained by cleavage are dissolved in 200 ml of cyclohexane, 56 g (0.56 M) of triethylamine are added and 56 g at RT to 50 ° C. for this purpose (0.56 M) trimethylchlorosilane was added dropwise in about 1 h. After a further 2 h at 50 ° C., the salt which has precipitated is pressed off, the filter cake is washed well with cyclohexane and the entire filtrate is distilled. After redistillation, the main fraction K is obtained_p1.5 143-8 ° C 110 g colorless liquid (n<maths id="math0001" num=""><math display="inline"><mrow><mfrac linethickness="0"><mrow><mtext>20</mtext></mrow><mrow><mtext>D</mtext></mrow></mfrac></mrow></math><img file="EP0348744A2_D0006.tif" /></maths> = 1.5558), which corresponds to the title compound by NMR and is at least 95% (67% of theory).

1.4 Reaction of a "living" polystyrene anion with 4-trimethylsilyloxy-1,1-diphenylethylene (preparation of the polymer according to formula (II) with R⁷ = Si (R⁵)

6.5 ml of a 2.5 molar n-butyllithium solution (in hexane) were added to a mixture of 800 ml of toluene and 100.2 g of styrene under an N₂ atmosphere by means of a syringe with rapid stirring at room temperature, during which the solution colored orange-red. The temperature was then raised to 40 ° C. After a polymerization time of 3 h, the solution was brought to room temperature and 45 ml of a solution of 10 g of 4-trimethylsilyloxy-1,1-diphenylethylene and 60 g of toluene were added by means of a syringe, the color of the solution changing to dark red. The reaction time was 1 h at room temperature. The polymer was then neutralized with 2 ml of methanol (N₂-saturated) and isolated by precipitation in methanol.

1.5 Cleavage of the silyl ether

(Preparation of a polymer according to formula (II) (R⁷ = H)

20 ml of a 10% aqueous hydrochloric acid were added at 40 ° C. to a solution of 100 g of the polymer described in the above example in 800 ml of tetrahydrofuran. The reaction time was 1 hour. The polymer was then precipitated in methanol, washed neutral and dried.

GPC analysis (polystyrene calibration): M_n = 6,500 g / mol, M_w = 7,900 g / mol.

2.1 Implementation of a "living" polystyrene di-anion with 4-trimethylsilyloxy-1,1-diphenylethylene (preparation of the polymer according to formula (III) with R⁷ = Si (R⁵) ₃)

4 g (0.031 mol) of naphthalene are added to 0.55 g (0.024 mol) of sodium in 250 ml of tetrahydrofuran under an N₂ atmosphere, the solution turning an intense green color. After about 2 hours at room temperature, the sodium had completely converted to naphthalene sodium. Then 50 g of styrene were added dropwise with a syringe over 2 hours, the color changing to red. After a further 30 min, a solution of 8 g (0.03 mol) of 4-trimethylsilyloxy-1,1-diphenylethylene and 15 ml of toluene was added using a syringe. After a reaction time of 2 h at room temperature, the polymer was neutralized with methanol (N₂ saturated) and isolated by precipitation in methanol.

2.2 Cleavage of the silyl ether (preparation of the polymer according to formula (III) with R⁷ = H)

35 ml of 10% strength aqueous hydrochloric acid were added to a solution of 45 g of the polymer described in the above example in 350 ml of tetrahydrofuran at 40 ° C. After a reaction time of one hour, the polymer was precipitated in methanol, isolated, washed neutral and dried.