DE2653767A1 - Oligomeric brominated aromatic phosphite derivs. - for flame-proofing polyester, prepd. from tri:aryl phosphite and bromine-substd. bisphenol - Google Patents

Abstract

New oligomeric aromatic phosphites are of formula (I): (where R is opt. substd. aryl; R1 is R or (ii); X is -O-, -S-, -SO2-, a covalent bond or a 1-6C alkylidene, esp. -CMe2-; and n is integer 1-10). (I) having mol. wt. 1800 was prepd. by reacting tetrabromobisphenol A and triphenyl phosphite. (I) are heat-stable up to 350 degrees and are used for flame-proofing high-melting synthetic resins, esp. polyesters, e.g., polyethylene- or polybutylene terephthalate. When worked into polyesters, (I) cause no crosslinking via the phosphite gps.

Description

Oligomeric Aromatic Phosphites and a Process

for their preparation It is known to use triaryl phosphites in the presence of dialkyl, diaryl phosphites and bases as catalysts, such as alcoholate, to transesterify with aliphatic alcohols or phenols with elimination of phenol. Here all three aryl groups of the triaryl phosphite are exchanged one after the other. Examples for such reactions can be found in "Houben-Weyl", Methods of Organic Chemistry, Vol. 12/2, pp. 59 ff. And in US Pat. No. 3,375,304. In the implementation of triaryl phosphites with diols or bisphenols you have to use the phosphite in a clear excess, so that no crosslinked polymer is formed during the transesterification.

The use of a diol or bisphenol excess is less favorable, since networking is always to be expected under such conditions. In the US patent 3,375,304 therefore exclusively describes polyphosphites with phosphite end groups.

These phosphite end groups in polymers are, however, for some areas of application undesirable, especially when such compounds contain OH groups in the presence Substances should be used. The terminal aryl phosphite groups are very sensitive to transesterification or saponification. This is how it becomes such Polymers already at room temperature with aliphatic alcohols trialkyl phosphite or split off phosphorous acid with water.

This disadvantage is particularly noticeable when such polyphosphites to be incorporated into polyester resins or into polyurethanes. When incorporating in polyester these phosphites can cross-link with elimination of phenol Cause phosphite groups, as there are always OH end groups in polyesters. In the case of polyurethanes, the reaction with the polyol component results in the OH / NCO ratio changed, in addition, such polyurethanes are due to their alkyl phosphite content generally malodorous, which of course greatly affects their use.

An alternative synthesis for monomeric or polymeric triaryl phosphites consists in the reaction of phosphorus trihalide with phenols and / or bisphenols, as described for example in BE-PS 770 107, US-PS 3,159,533 and US-PS 3,492,373. This reaction is possible with phenols or bisphenols which are ortho-halogen-substituted on all sides but very difficult to do. This is how, for example, the implementation of 2,4,6-trichlorophenol with phosphorus trichloride in 280 hours at reflux temperature only with an 11% yield of triaryl phosphite, whereas the 2,4,5-trichlorophenol settles under the same conditions to 90% in 10 to 20 hours, see "Houben-Heyl", Methods of Organic Chemistry, Vol. 12/2, page 16.

It has been found that you can aromatic polyphosphites without the described can produce undesirable properties in smooth reaction when used as a diol component Bisphenols are used, all of which are ortho to the OH group by bromine are substituted. With these connections it is possible without crosslinking phenomena Triaryl phosphite and bisphenol even when using an excess of bisphenol to transesterify with each other.

The invention thus relates to polyphosphites of the general formula in which R is an optionally substituted aryl radical, R 'R or preferably X 0, S, SO2, a single bond or an alkylidene radical with up to 6 carbon atoms and n is an integer from 1 to 10.

The invention also relates to a process for the preparation of these compounds, which is characterized in that an aryl phosphite of the general formula with a bisphenol of the general formula in which X and R have the abovementioned meaning, are reacted with one another at temperatures from 100 to 3000C, preferably from 120 to 250C, with base catalysis in vacuo, with the phenol formed being distilled off.

The molar ratio of bisphenol to phosphite is preferably 1.5 to 0.9, very particularly preferably 1.3 to 0.98.

The smooth and crosslink-free course of the reaction is surprising, because in the transesterification of unsubstituted or

completely o-methyl- or o-chloro-substituted bisphenols with Triaryl phosphite in the stated molar ratios is obtained from weakly to strongly crosslinked, infusible polymers. When using the brominated bisphenols against it two aryloxy groups of the phosphite are smoothly substituted, while the third in the above Temperature range is not exchanged.

Non-volatile bases are preferably used as the catalyst for the transesterification however, the alkali phenolates corresponding to the aryl radical in the phosphite. You are preferred in Amounts up to 15 mol%, based on phosphite, are used.

It is particularly favorable to carry out the transesterification initially without a catalyst to begin and then with decreasing phenol cleavage the phenolate in Add small portions of 1 to 2 mol% until the expected amount of phenol is distilled off.

Because of the volatility of the triaryl phosphites, it is advantageous to use the To start transesterification at the beginning at about 120 to 1500C at a pressure above 15 mbar; only with progressive splitting off of phenol does the temperature slowly rise to 200 bis Raised 2500C and reduced the pressure as much as possible.

In a preferred form of the method according to the invention Triaryl phosphite and tetrabromobisphenol mixed and at a pressure of 15 to 30 mbar heated to 120 to 1500C. Phenol is slowly split off. if the distillation becomes slower, 1 to 2 mol% of alkali metal phenolate is added, whereupon the transesterification proceeds faster again. After about half of the phenol is split off the temperature is increased slowly and the catalyst is occasionally replaced. Depending on the type of bisphenol and the desired degree of condensation, the temperature is raised to 200 up to 2500C, due to the discoloration that often occurs at higher temperatures Temperatures above 2500C less favorable.

The total amount of catalyst required is about 5 mol% however, the catalyst is added in one portion right at the beginning of the transesterification, thus higher amounts of up to about 15 mol% may also be necessary.

In a second preferred form of the method according to the invention one puts the triaryl phosphite in the reaction vessel from phosphorus trichloride and the phenol concerned without intermediate isolation. The tetrabromobisphenol can also be used already be present. The molar ratio of phenol to phosphorus trichloride should be at least 1, but preferably 2 to 3.5. The phenol is added at room temperature, Possibly.

in a mixture with the tetrabromobisphenol, with phosphorus trichloride, stirred for a while at room temperature and then slowly heated to 180 ° C while stirring, whereby HCl is released. Then add tetrabromobisphenol to the calculated amount and draws the rest of the HCl and excess and that which is released by transesterification Phenol in vacuo and condenses after the addition of 5 to 15 mol% sodium phenolate the end. Tetrabromobisphenols alone only react under the conditions described very slowly with phosphorus trichloride. In this reaction variant, however, is the achievable degree of condensation not as high as with the transesterification of pure triaryl phosphite. When the transesterification has ended, the melt is allowed to solidify and comminute.

Further purification is achieved by dissolving in an inert solvent such as methylene chloride, chloroform, carbon tetrachloride, chlorobenzene, Dimethylformamide or N-methylpyrrolidone and precipitation with a suitable nonsolvent such as methanol, ethanol, acetone, ethyl acetate, gasoline, -Ligroin or Petroleum ether. Products reprecipitated in this way generally have a higher degree of condensation and softening point. Sometimes the polyphosphite is purified of adhesive Residual phenol by stirring in methanol or acetone at -10 to + 30 ° C. The polyphosphites obtained in this way are colorless to yellow powders or light brown glassy masses in the solidified state. The achievable molecular weights are between 1000 and 7000 depending on the equivalence during transesterification.

All triaryl phosphites can be obtained by the process according to the invention use which, during transesterification, release a phenol with a boiling point below 2300C, the preferred phosphite is triphenyl phosphite.

Examples of tetrabrominated bisphenols are: bis- (3, 5-dibromo-4-hydroxyphenyl) ether; Bis (3,5-dibromo-4-hydroxyphenyl) sulfide; Bis (3,5-dibromo-4-hydroxyphenyl) sulfone; Bis (3,5-dibromo-4-hydroxyphenyl) methane; 1,1-bis (3,5-dibromo-4-hydroxyphenyl) ethane; 1,1-bis (3,5-dibromo-4-hydroxyphenyl) cyclohexane; Bis (3,5-dibromo-4-hydroxyphenyl) ketone, 2,2-bis- (3,5-dibromo-4-hydroxyphenyl) propane (tetrabromobisphenol-A) are preferred and 3.5; 3 ', 5'-tetrabromo-4,4'-dihydroxydiphenyl.

The new connections take place because of their thermal stability up to 3500C preferably used as a flame retardant for high-melting synthetic resins, in particular for polyester such as polyethylene or polybutylene terephthalate.

In the following examples the parts given are parts by weight.

Comparative Examples a) 456 parts of 2,2-bis (4-hydroxyphenyl) methane are together with 620 parts of triphenyl phosphite and 25 parts (12.5 mol%) of sodium phenolate slowly heated to 150 ° C. in vacuo at 10 to 15 mbar with stirring. Distilled in the process Phenol, the mixture crosslinks and is insoluble in all common solvents, the softening point is above 3000C.

b> Comparative example a) is repeated, but used 568 parts of 2,2-bis (3,5-dimethyl-4-hydroxyphenyl) propane. You get a networked Polyphosphite.

c) A mixture of 620 parts of triphenyl phosphite, 736 parts of 2,2-bis- (3, 5-dichloro-4-hydroxyphenyl) propane and 25 parts of sodium phenolate is used initially heated to 150 ° C. at approx. 15 mbar with stirring, phenol is split off in the process.

After 2 hours, the mixture is heated to 2000C at 1 mbar pressure and distilled continue phenol. The transesterification is broken after 350 parts of phenol have been obtained (87.5% of theory) and receives an almost uncrosslinked polyphosphite, softening point 100-102 ° C. If this product is 10% of a polyethylene terephthalate melt at approx.

270 to 2900C, crosslinking occurs, the melt is not can be spun into fibers. Even when trying to split off the phenol by lengthening it to complete the transesterification time at 2000C or by post-reaction at 2400C, crosslinking of the polyphosphite occurs.

d) (comparison analogous to US Pat. No. 3,375,304) 1224 parts of 2,2-bis- (3,5-dibromo-4-hydroxyphenyl) methane (tetrabromobisphenol-A, TBBA), 930 parts triphenyl phosphite (molar ratio Bisphenol / phosphite = 0.75) and 20 parts of sodium phenolate are used at 150 to 2100C reacted with one another at 1 mbar pressure, thereby distilling 535 parts of phenol containing 0.0 8% P, from, a total of twice 10 parts of sodium phenolate are added each time. 1620 parts of a glass-like solidifying melt at the softening point are obtained 72 to 76 ° C. Forms in a methanolic suspension of the ground mass Trimethyl phosphite, the presence of which in methanol can be demonstrated by gas chromatography leaves. If 10% of the product is added to a polyethylene terephthalate melt, so the viscosity of the polyester rises sharply and the mass can no longer be stirred and cannot be spun into fibers.

analysis CHP ~ Br calculated 42.1% 2.6% 5.4% 41.6% found 41.0% 2.3% 5.2% 41.8% Example 1 A mixture of 1088 parts of tetrabromobisphenol A and 620 parts of triphenyl phosphite are slowly brought to approx.

Heated at 1500C at 1 mbar pressure until the elimination of phenol subsides. Then 5 parts of sodium phenolate are added and the mixture is again distilled over a small one Phenol column. After approx.

The temperature is increased to 2000C / 1 mbar for 2 hours. It will two more 5 parts of sodium phenolate each time.

Stirring is continued until the splitting off of phenol has ended, in total 351 parts of distillate with 1.15% P content are obtained, corresponding to 40 parts of triphenyl phosphite, this corresponds to a corrected bisphenol / phosphite molar ratio = 1.07.

1360 parts of a light red-brown melt remain in the reaction vessel, which solidifies to a glassy mass. M.p .: 84 to 900C.

Analysis of the raw product CHP Br calculated 37.8 2.3 4.7 48.0 found 39.8 2.4 4.5 47.3 a) 100 parts of the crude product are ground and stirred up in 250 parts of methanol at 0 ° C. for 1 hour. After drying, 99.5 parts are obtained back.

M.p .: 88 to 94 ° C; #rel = 1.04 (1% in CH2Cl2) / 20 ° C molar weight: 1800 (osmometric in CHCl3) analysis 1 CHP Br found 39.5 2.3 4.6 45.4 0.2% trimethyl phosphite and 0.01% phenol can be detected in the methanol filtrate by gas chromatography.

b) 100 parts of the crude product are ground and dissolved in 200 parts of methylene chloride dissolved, stirred with activated charcoal, filtered and the filtrate in excess methanol pleases.

Yield: 61.5 parts, melting point: 98 to 1040 ° C. Molecular weight: 1950 (osmometric in CHC13) analysis CHP Br found 38.3 1.8 5.4 47.8 0.2% trimethyl phosphite and 0.1% phenol can be detected in the precipitant filtrate by gas chromatography.

Example 2 Example 1 is repeated, but it is at 2200C / 0.8 mbar condensed out.

Crude yield: 1340 parts phenol distillate: 355 parts m.p .: 86 to 890C That The crude product is obtained as in Example 1 b) by reprecipitation from methylene chloride / methanol cleaned, you get 911 parts.

M.p .: 123 to 1260C; Molecular weight: 4400 (osmometric in CHC13) analysis CHP Br calculated 37.8 2.3 4.7 48.0 found 38.3 2.5 4.8 50.2 Gas chromatography shows less than 0.01% trimethyl phosphite and 0.03% phenol in the precipitant filtrate.

Example 3 Example 1 is repeated, but it is at 2400C / 0.5 mbar condensed out.

Crude yield: 1230 parts, melting point: 105 to 1100C Xrel = 1.12 (1% in CH2Cl2) / 20 ° C analysis CHP Br calculated 37.8 2.3 4.7 48.0 found 37.2 2.0 5.5 47.7 a) 100 parts of the crude product are stirred in 200 parts of methanol at OOC for 1 hour.

Yield: 95 parts, melting point: 119 to 1250 ° C.% real = 1.1 (1% strength in CH2Cl2) / 20 ° C. analysis C f HP Br found 37.4 2.4 5.4 47.3 In the methanol filtrate, trimethyl phosphite is only detectable in traces by gas chromatography, phenol is found to be 0.5%.

b) 100 parts of crude product are worked up as in Example 1 b).

Yield: 72 parts melting point: 129 to 1330 ° C. Molecular weight: 6300 (osmometrically in CHCl3) analysis CHP Br found 37.6 2.2 5.2 47.3 Example 4 1415 parts of bis (3,5-dibromo-4-hydroxyphenyl) sulfone, 775 parts of triphenyl phosphite and 80 parts of sodium phenolate are heated to 2000 ° C./0.8 mbar with stirring. 460 parts of phenol are distilled off. The crude product is dissolved in methylene chloride, stirred with activated charcoal, filtered and isolated by concentration.

Yield: 1550 parts, melting point: 51 to 530C%, real = 1.08 (1% in CH2Cl2) / 20 ° C Example 5 1255 parts of 3,3 ', 5,5'-tetrabromo-4,4'-dihydroxy-diphenyl, 775 parts of triphenyl phosphite and 50 parts of sodium phenolate are at 150 to 2000C stirred at 0.5 mbar, 430 parts of phenol distilling off.

Crude yield: 150 g m.p .: 41-460C analysis CHP! Br calculated 34.6 1.5 5.0 1 51.3 found 35.7 1.9 5.4 | 49.9 Example 6 1360 parts of tetrabromobisphenol-A, 620 parts of triphenyl phosphite and 20 parts of sodium phenolate are condensed first at 1500 ° C. and later at 200 ° C. at a pressure of 0.5 mbar, giving 370 parts of phenol (# 98.4%). The yield of crude product is 1580 parts (5 98.5%). It is comminuted and stirred in 3000 parts of methanol for 60 minutes, filtered off with suction and dried at 50 ° C. in vacuo.

Fp .: 76 to 81 ° C. Molecular weight: 1220 (osmometric in CHCl3) analysis CHP Br calculated 37.8 2.3 4.7 48.1 found 38.2 2.2 5.0 47.4

Claims (8)

Claims 1) Compounds of the general formula (I) in which R is an optionally substituted aryl radical R 'R or X 0, S, S02, a single bond or an alkylidene radical with up to 6 carbon atoms and n is an integer from 1 to 10. 2) Compounds according to claim 1, characterized in that in the general formula (I) X represents the isopropylidene radical CH3-C-CH3. 3) compounds according to claim 1, characterized in that in the general formula (I) X represents a single bond. 4) Process for the preparation of compounds of the general formula (I) in which R, R ', X and n have the meaning given in claim 1, characterized in that a triaryl phosphite of the general formula P- (OR) 3 with a bisphenol the general formula at temperatures of 100 to 3000C with base catalysis in vacuo while distilling off the phenol formed with one another. 5) Method according to claim 4, characterized in that the molar ratio from bisphenol to triaryl phosphite is from 1.5 to 0.9. 6) Method according to claim 4, characterized in that the Triaryl phosphite as an intermediate from PCl3 and the corresponding phenol and continues to implement without intermediate insulation. 7) Method according to claims 4 to 6, characterized in that that the bisphenol used is 2,2-bis (), 5-dibromo-4-hydroxyphenyl) propane. 8) Method according to claims 4 to 6, characterized in that that as bisphenol 3,3 '; 5,5'-tetrabromo-4,4'-dihydroxydiphenyl is used.