DE2648051A1 - POLYHYDROXIPHENOLS AND THE PROCESS FOR THEIR PRODUCTION - Google Patents

Description

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A 41 972 b k - 163

October 18, 1976

SOCIETA 'ITALIANA RESINE SIRSpA 33 , Via Grazioli
Milan, Italy

Polyhydroxy phenols and processes for their preparation

The invention relates to polyhydroxy phenols with the following structural formula:

Q—

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where R is an alkyl radical having 1 to 10 carbon atoms, the methylene bridges with respect to the Hydroxy1 group on the central phenol ring in the ortho position and attached to the other phenol rings in the ortho or para position.

The invention also relates to a method for producing such polyhydroxiphenols, the production takes place in such a way that formaldehyde is reacted with phenol, which is in the para position with an alkyl group is substituted by 1 to 10 carbon atoms to the dimethylol derivative to be obtained by substituting with two methylol groups, in the ortho positions with respect to the Hydroxy1 group of the substituted phenol, which one then the dimethylol derivative reacts with phenol to form a Obtain polyhydroxyphenol with the structural formula (I).

In the description below:

the term "para-substituted phenol" is a phenol which, with respect to its hydroxyl group in the para position, has a Alkyl group is substituted by between 1 and 10 carbon atoms;

the term "dimethylol derivative" or "dimethylol intermediate" the para-substituted phenol in which there are two methylol groups in the ortho positions with respect to the hydroxy1 group are substituted;

the term "polyhydroxiphenol" means a compound with the structural formula (I).

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The process for producing the polyhydroxyphenol according to the invention is characterized by the following process steps:

(a) One leaves formaldehyde and a substituted phenol with the following structural formula

react with one another, where R is an alkyl radical with 1 to 10 carbon atoms, namely with a molar one Ratio of formaldehyde to phenol of at least 2: 1 and in the presence of an inorganic base and at a temperature of at least 40 ° C, so as to obtain a dimethylol derivative of phenol;

(b) the reaction products of the process step are used

(a) an acid in an amount at least equivalent to that of the inorganic base, namely in the presence of water, and separating the aqueous Phase from the methylol derivative phase thus obtained;

(c) the dimethylol derivative phase is an organic one Solvent, which can dissolve the derivative, normally immiscible or only slightly miscible with water is and forms an azeotropic mixture with the latter, bringing the resulting solution in the presence of one acidic catalyst and at a temperature of at least 100 ° C in contact with phenol, namely with a

-A-

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molar ratio of phenol to derivative of at least 2: 1 and the mixture obtained is kept at the boiling point until the reaction between the derivative and the phenol is essentially complete is, while the water formed is distilled off as an azeotrope with the organic solvent and

(d) the polyhydroxyphenol is recovered from the reaction products of process step (c).

Process step (a)

According to the process according to the invention, formaldehyde is reacted with a para-substituted phenol, the latter preferably being one of the following substances: para-tert-butylphenol, para-cresol, para-octylphenol, para-amylphenol or para-nonylphenol. The formaldehyde can do that
Reaction medium are supplied in the form of an aqueous solution, in particular in the form of a commercially available aqueous solution
Solution., The formaldehyde content of which is between 37 and 38 percent by weight. Lower polymers of formaldehyde, such as, for example, paraformaldehyde or any other substance which releases formaldehyde under the reaction conditions, can also be used according to the invention.

An inorganic base, and preferably an alkali metal hydroxide, such as sodium, potassium or Lithium hydroxide as a catalyst.

The molar ratio of formaldehyde to para-substituted

- 5+) p-tert-butylohenol

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Phenol is generally between 2: 1 and 3: 1, while the molar ratio of inorganic base to para-substituted Phenol is generally between 0.3: 1 and 1: 1.

The reaction is also preferably carried out at a temperature between 40 and 80 C, for a period of time within this it is ensured that the para-substituted phenol reacts completely or at least to the extent that its Concentration in the reaction medium is reduced to values below 0.5 percent by weight.

The reaction time is generally between 1 and 4 Hours.

The way in which the reactants are brought into contact with one another is not critical. Preferably, however an aqueous solution of the inorganic base to the reaction medium, which contains formaldehyde and para-substituted phenol, gradually added, the reaction mixture after completion of the addition of the inorganic base still for a certain amount of time Time is kept at the reaction temperature.

The reaction is generally carried out in the presence of water. Preferably the reaction mixture should not contain more than 50 percent water by weight.

According to a preferred embodiment, the molar The ratio of alkali metal hydroxide to para-substituted phenol at about 0.5: 1 and that of formaldehyde to para-substituted Phenol held at about 2.5: 1. Will continue

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the reaction is carried out at a temperature of the order of 6O ° C, wherein
hydroxide is added.

60 C carried out, the reaction medium being aqueous sodium

The para-substituted reacts under the given conditions Phenol almost completely with the formaldehyde within a period of about 2.5 hours.

Process step (b)

The reaction product according to process step (a) becomes acid added in an amount which is at least the amount of the inorganic base added during process step (a) is equivalent.

Organic acids can be used for the stated purpose. However, mineral acids are preferably used, such as hydrochloric acid, sulfuric acid or phosphoric acid. Of these, phosphoric acid is again the most advantageous because of corrosion.

In general, such an amount of acid is added that a pH value between 6.5 and 2 results in the reaction medium.

Following the treatment with acid, the dimethylol intermediate becomes insoluble in water so that it can be separated from the aqueous phase, which contains the formaldehyde, which did not take part in the reaction and the neutralization products of the inorganic base. At this point it should be noted that if during the procedure

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Step (a) no water was present, the water is added during process step (b).

In a preferred embodiment, the reaction products the first process step is cooled to about 50 C, whereupon the phosphoric acid is gradually added until an equivalent ratio of sodium hydroxide to phosphoric acid in the order of magnitude of 0.5: 1 is reached. The mixture is then decanted at 40 to 50 C, the aqueous layer (which is poured away) from the organic Layer is separated, which consists essentially of the dimethylol intermediate consists.

Process step (c)

The dimethylol intermediate which is obtained in process step (b) becomes an organic solvent added, which can dissolve the intermediate product, which is normally not or only slightly miscible with water and which forms an azeotropic mixture with the latter.

For this purpose, aromatic hydrocarbons such as toluene, xylene, cumene or other alkylbenzenes are advantageous, welcl
tet.

which boil at a temperature that does not exceed 160 C

The solution obtained in this way is generally added in such an amount that a molar ratio of para-substituted phenol (which is added during process step (a)) to the phenol between 1: 2 and

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1: 3.5 is guaranteed.

The reaction is carried out at the boiling point, in general at a temperature between 100 and 160 ° C., the water being formed continuously in the form of an azeotrope is distilled off with the selected organic solvent.

The reaction of the intermediate dimethylol with the phenol is carried out in the presence of an acidic catalyst, preferably an organic acid.

Said acid should preferably have an acid dissociation constant or (in the case of a polybasic acid) have a first acid dissociation constant which is greater than 1.10. Examples of organic acids which are suitable for this purpose are: oxalic acid, benzoic acid, para-tert-butybenzoic acid, Salicylic acid and isophthalic acid.

The amount of the acidic catalyst is usually between 0.1 and 5 parts by weight per every 100 parts by weight of the Phenol.

The reaction times are those which are required for a practically complete reaction of the dimethylol derivative and are generally between 2 and 4 hours.

In a preferred embodiment, this is selected in the Solvent dissolved dimethylol intermediate added to the phenol and the catalyst, the reaction

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mixture is kept at the boiling point. The evolving Vapors are condensed, whereby an aqueous phase is separated, which is discharged and an organic one Phase which is fed back to the reaction medium.

Process step d

The acid catalyst, the organic solvent and optionally Excess phenol is separated from the reaction products obtained in process step (c).

In the event that oxalic acid is used, this acid is in the order of magnitude in the reaction medium at temperatures insoluble between 30 and 40 ° C. The acid can thus precipitated by cooling the reaction mass and then filtered off.

In other cases it may be necessary to use the acid catalyst to neutralize and filter off the salt which then results as a precipitate.

The organic solvent and the excess phenol can be removed by distillation, namely the former at or near atmospheric pressure and the latter at a negative pressure, preferably working according to the thin-film process will. It goes without saying that the organic solvent and the phenol are then fed back into the process can be used to produce the polyhydroxy phenol. The latter remains in any case as a distillation residue.

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In the process described, the polyhydroxyphenol is in

,obtain

its isomeric forms / which are useful for the same purposes for which polyhydroxy phenols are commonly used will. It will be understood that, if desired, the various isomers can be identified by using conventional methods, for example by fractional crystallization, can be separated from each other.

The polyhydroxy phenols according to the invention are particularly useful as anti-oxidants for elastomeric and plastic materials suitable, as well as polymerization inhibitors for unsaturated monomers such as styrene and the alkyl esters of the acrylic or Methacrylic acid, and as stabilizers for unsaturated polyester resins, i.e. for polycondensation products of unsaturated polybasic acids and polyhydroxy alcohols, which are in styrene or another unsaturated monomer are dissolved.

The polyhydroxy phenols according to the invention are also suitable for the production of epoxy resins if they are used with Brings epichlorohydrin to reaction in an alkaline medium, the epoxy resins mentioned being particularly suitable for paints are to improve their temperature resistance, dimensional stability and resistance to chemical substances.

Novolak phenolic resins with higher molecular weights than that usual can be prepared by using the polyhydroxy phenols with the structural formula (I) in an acidic medium to react with formaldehyde, preferably in the presence of phenol or, more generally, of phenolic compounds.

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Resole phenolic resins can also be prepared, namely from the same starting products, but with different mixing ratios of the same and in a basic one Medium.

The novolaks are particularly "useful" when used in conjunction with hexamine as a binder for mineral aggregates (e.g. molding sand or abrasive particles) or vegetable Fillers, such as wood flour or the like, or as Reinforcement material or used as an adhesive for rubber.

The named resoles are particularly useful for impregnating papers and fabrics for making laminates as well after suitable modification with vegetable oils to produce hard and chemically resistant shiny ones Stoving enamels.

example

In the test data given below, the parts and percentages are unless expressly stated otherwise is, parts by weight or percentages by weight.

In a reaction system with an agitator, with a steam heating system, with a hypsometer, with a container for feeding the reagents, with a condenser, with a separator, with a return line for the condensate and a collecting tank for the distillate are 426.7 parts of the Para-tert-butylphenol and 604 parts of a 36% strength aqueous

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Entered formaldehyde solution. The molar ratio of formaldehyde to para-tert-butylphenol is therefore 2.5: 1.

The temperature is set to 60 ° C. and 190 parts of a 30% aqueous solution are added to the reaction mass with stirring Solution of sodium hydroxide added.

After adding the sodium hydroxide, the molar ratio of para-tert-butylphenol to sodium hydroxide is the same 2: 1. The temperature is then kept at 60 ° C. until the amount of free formaldehyde in the reaction medium is reduced to 4 to 4.5%.

Then 119 parts of a 75% aqueous phosphoric acid solution are then added added. Stirring is continued until neutralization is complete. The agitator will then shut down, and there are an aqueous phase, which contains sodium phosphates and the formaldehyde, which is not on the Reaction has participated, and an organic phase, which contains the dimethylol derivative of P-tert-butylphenol, from each other separated.

The aqueous phase is poured away and 360 parts of toluene are added to the organic phase (720 parts), so that a Toluene solution is obtained with the following values:

Dry matter: 52%

Viscosity at 25 ° C: 25 c ¹
No free para-tert-butylphenol!

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The last-mentioned values were obtained with the aid of a gas chromatography analysis determined.

A mixture of 737 parts of phenol and 32 parts of oxalic acid is heated to 100 ° C. and the heated mixture is then The toluene solution of the dimethylol intermediate was gradually added over a period of 3 hours. During the said period, the mass is kept at its boiling point, the water being distilled off by azeotropic distillation and is continuously discharged via a separator.

The toluene distilled off is returned to the reaction medium.

During the addition of the toluene solution, the temperature of the mass rises rapidly to 120 to 125 ° C. and maintains this Temperature at until the mixing process has ended. The molar ratio between the phenol and the (originally supplied) Para-tert-butylphenol in the reaction medium is then 2.7: 1.

After adding the toluene solution, the temperature mentioned is maintained for 30 minutes and the mass is then cooled to 30 to 40 ° C. At this temperature, the oxalic acid dispersed in the solution is removed by filtering.

The solution obtained in the manner described above had the following values:

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Dry matter: 64%

Viscosity at 40 ° C 900 Free phenol: 16%

The last-mentioned values were obtained with the aid of gas chromatography determined. .

The solution was then distilled at atmospheric pressure / with 253 parts of toluene, which contained small amounts of phenol, were distilled off.

The residue was then removed by the thin film method at a Distilled pressure of 3 mm Hg to remove residual toluene and free phenol.

Approximately 1000 parts by weight of a polyhydroxyphenol were obtained at the bottom of the evaporator, which had the following values:

Appearance: solid

Melting point (in capillary): 74 C Viscosity at 25 ° C in 50% ethanol solution: 33 cP pH value in 50% ethanol solution:

Gardner enamel color: 6 Free phenol (gas chromatography): ^ 0.5% Free para-tert-butylphenol (gas chromatography): absent

The product is soluble in most organic solvents.

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94

An analysis of the NMR spectrum (. Nuclear resonance spectrum) led to the following results:

Mn (OM) = number average molecular weight: 36

η = average number of OH groups per molecule: 3.0

R = average number of aromatic protons per ring: 3.0

= average number of methylene bridges per benzene ring: 0.6

Isomers: Ortho-Ortho ¹ : 5% Ortho-Para: 95% Molar ratio of para-tert-butylphenol to phenol: 1: 2

The end product obtained is therefore a polyhydroxyphenol of structural formula (I) in its two isomeric forms.

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Claims (4)

Patent claims: 2 ί J 2 ^ v / obei R is an alkyl radical with 1 to 10 carbon atoms, the methylene bridge ^ with respect to the HydroxyI group on the central phenolic ring in the ortho position and on the other phenolic rings in the ortho or Para position bound bind. 2. Process for producing a polyhydroxyphenol according to Claim 1, characterized by the following process steps : (a) One leaves formaldehyde and a substituted phenol with the following structural formula react with one another, where R is an alkyl radical having 1 to 10 carbon atoms, namely at a molar ratio of formaldehyde to phenol of at least 2: 1 and in the presence an / organic base and at a temperature - 17 - 709820 / 10A6 k - 163 October 18, 1976 - from-at least 40 C to this way one To obtain dimethylol derivative of phenol; (b) an acid is added to the reaction products of process step (a) in an amount which that of the inorganic base is at least equivalent, in the presence of Water and the aqueous phase is separated from the methylol derivative phase obtained in this way; (c) the dimethylol derivative phase is added to an organic solvent which can dissolve the derivative, is normally not miscible or only slightly miscible with water and forms an azeotropic mixture with the latter, the resulting solution is brought in the presence of an acidic catalyst and at a temperature of at least 100 ^° C. in contact with phenol, specifically at a molar ratio of phenol to derivative of at least 2: 1, and the mixture obtained is kept at the boiling point until the reaction between the derivative and the phenol is essentially is completely complete, while the water that forms is distilled off as an azeotrope with the organic solvent and (d) the polyhydroxyphenol is obtained from the reaction products of process step (c). - 18 - 09820/1048 k - 163 October 18, 1976 - 3. The method according to claim 2, characterized in that the substituted phenol is one of the following substances: Para-tert-butylphenol, para-cresol, para-octylphenol, Para-amylphenol, para-nonylphenol. 4. The method according to claim 2 or 3, characterized in that the formaldehyde in the reaction medium of process step (a) in the form of an aqueous solution or in The form of a compound is added which releases the formaldehyde under the reaction conditions. 5. The method according to any one of claims 2 to 4, characterized in that the molar ratio of formaldehyde to phenol is between 2: 1 and 3: 1. 6. The method according to any one of claims 2 to 5, characterized in that the inorganic base is an alkali metal hydroxide where is the molar ratio between the inorganic base and the substituted phenol is between 0.3: 1 and 1: 1. 7. The method according to any one of claims 2 to 6, characterized characterized in that process step (a) is carried out at temperatures between 40 and 80 ° C. 8. The method according to any one of claims 2 to 7, characterized characterized in that process step (a) is carried out for a period of 1 to 4 hours. - 19 - 709820/1046 k - 163 October 18, 1976 - 9. The method according to any one of claims 2 to 8, characterized in that the reaction mixture in the process step (a) contains no more than 50 percent water by weight. 10. The method according to any one of claims 2 to 9, characterized characterized in that the acid of process step (b) is an inorganic acid. 11. The method according to any one of claims 2 to 10, characterized characterized in that one of the following acids is used in process step (b): hydrochloric acid, sulfuric acid, phosphoric acid. 12. The method according to any one of claims 2 to 11, characterized in that during the process step (b) the acid is added in such an amount that a pH value between 2 and 6.5 results. 13. The method according to any one of claims 2 to 12, characterized characterized in that the organic solvent used is an aromatic hydrocarbon with a boiling point v / s, which is not above 160 ° C. 1.4. The method according to any one of claims 2 to 13, characterized in that the phenol during the process step (c) in an amount of 2 to 3.5 moles per mole of that added during process step (a) substituted phenol added. - 20 - 709820/1046 A 41 972 b 26A8051 k - 163 October 18, 19 76 - 15. The method according to any one of claims 2 to 14, characterized in that in the process step (C) the mixture obtained boils at a temperature between 100 and 16O ^{0 C.} 16. The method according to any one of claims 2 to 15, characterized characterized in that an organic acid is used as the acidic catalyst. 17. The method according to any one of claims 2 to 16, characterized in that the acidic catalyst is a Acid used, which has an acid dissociation constant or (in the case of a polybasic acid) a first ι sits. first acid dissociation constant of over 1.10 18. The method according to any one of claims 2 to 17, characterized in that one of the following substances is selected as the acidic catalyst; Oxalic acid, benzoic acid,
Para-tert-butylbenzoic acid, salicylic acid, isophthalic acid. 19. The method according to any one of claims 2 to 18, characterized in that the acidic catalyst in
in an amount between 0.1 and 5 parts by weight per 100 parts of the phenol. 20. The method according to any one of claims 2 to 19, characterized in that process step (c)
performs for a period of 2 to 4 hours, - 21 - 709820/1046 k - 163 October 18, 19 76 - «Ί-- 21. The method according to any one of claims 2 to 20, characterized in that the Polyhydroxipheno1 wins, by precipitating the acid catalyst and removing the precipitate thus obtained and then by the organic solvents and the free phenol are distilled off from the reaction products of process step (c). 909,820 / 104e