JPH0655688B2 - Method for producing hydroxyaryl aldehyde - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing 2-hydroxyaryl aldehydes.

Such aldehydes and their derivatives are useful as intermediates in many applications, for example in the production of perfumes, pesticides, stabilizers and many compounds of industrial importance, such as oximes used in hydrometallurgical extraction. For this latter use, the 2-hydroxyaryl aldehydes are preferably prepared in pure form free of dialdehydes. British Patent No. 1530248 and J
From the paper CS (Perkin I, 1980 p. 1862 et seq.), By reacting an aldehyde with a phenolic compound in the presence of an amine and anhydrous tin chloride, -CHO
It is known that groups can be selectively introduced at the 2-position relative to the -OH group of phenolic compounds. In the latter document, it is postulated that tin chloride reacts with phenol to form tin phenoxide, which acts as a catalyst for introducing the formyl group adjacent to the OH group of the phenol ring. It is believed that the amine is required to absorb the HCl generated during the formation of the phenoxide, and lesser or greater amounts of amine than are needed for this purpose are associated with yield and selectivity. It has been shown to adversely affect both. It is also known that strongly basic amines capable of forming a stable complex with tin phenoxide are not very satisfactory for the above reaction. Support for this mechanism is found in the reaction of formaldehyde with phenolic compounds in the presence of soot phenoxide itself (the yield of this reaction is only reported to be satisfactory).

Another paper by some of the authors of the above document [JSC
(Perkin II), pp. 407 pp. 1980], dehydrogenation of 2-hydroxymethylphenol compounds to 2-formylphenol compounds using ketones or aldehydes as hydride acceptors and tin phenoxide as catalyst. The reactions that have been shown to be adversely affected by the presence of amines. Furthermore, if the aldehyde is aliphatic, dehydrogenation will not proceed.

The reaction method considered in the first article has a number of drawbacks, especially for commercial scale operations.
The presence of formaldehyde and HCl or amine hydrogen chloride salt and by-product methanol in the same reaction mixture is expected to result in the formation of chloromethyl ethers and methyl chloride, which are carcinogenic. The yields and selectivities of such reaction processes appear to depend on the use of about 10 mol% tin chloride and up to 40 mol% amine, based on the phenolic compound, which are of commercial operation for the reaction process. It adds significantly to the cost and presents a serious disposal issue for emissions.

The good selectivity of formylation at the 2-position of phenols is due to the absence of carcinogenic by-products by reacting formaldehyde with phenolic compounds in the presence of tertiary amines and relatively low concentrations of organotin compounds. It was found that the organooxytin compound had a pH of 6 to 10 when the aqueous medium was extracted with water.
Provided that it has a value).

According to the present invention, (1) a tertiary amine and (2) one or more compounds of the formula Sn (OR) ₄ (where R is an organic group) are used, and the aqueous solution obtained when extracted with water Medium is 6-10
Formaldehyde is reacted with a phenol compound having no substituent at the 2-position in an anhydrous (dry) medium in the presence of a catalyst consisting of a tin composition having a pH value of 2-. A method of making a hydroxyaryl aldehyde is provided.

The phenolic compound may be substituted at any or all positions with any group other than the 2-position that does not interfere with the reaction of the present invention and is preferably electron repulsive or weakly electrophilic. Examples of suitable phenol compounds include phenol itself, 4-alkylphenols (eg, 4-cresol and 4-t-butylphenol).
And an alkyl group containing 5 to 20, preferably 7 to 12 carbon atoms (such as 4-nonylphenol) 4-
There are alkylphenols.

The process of the present invention is particularly useful for the preparation of 2-hydroxy-5-alkylbenzaldehydes, which are intermediates in the preparation of metal extractants based on 2-hydroxy-5-alkylbenzaldoximes. For example, from 4-nonylphenol consisting of an isomer mixture containing linear and branched nonyl groups derived from phenol and propylene trimer, 2
A mixture of isomers of -hydroxy-5-nonylbenzaldoxime can be prepared.

Both free gaseous formaldehyde, formaldehyde solutions in anhydrous solvents, and polymeric forms (eg paraformaldehyde and other conventional formaldehyde-releasing reagents) can be used in the process of the invention. Paraformaldehyde has been found to be a particularly convenient source of formaldehyde. If a high conversion of the phenolic compound is required, the formaldehyde: phenolic molar ratio should be at least 2: 1 and preferably 2: 1 to 4: 1. Since one formyl group is introduced and one molecule is reduced to methanol, two molecules of formaldehyde are needed). However, when the method of the present invention is used to prepare 2-hydroxyaryl aldehydes that are further converted to oximes for use in hydrometallurgical extraction processes, the oximes can be used in admixture with free phenol. So not all phenol is consumed. For such end uses, the formaldehyde: phenol ratio is 0.5: 1.
However, it is preferably 0.8: 1 to 2: 1.
Is the range.

It has been found that the concentration of dialdehyde by-product is relatively low, even when using high formaldehyde: phenol molar ratios in the process of the present invention. This is important in the production of intermediates for metal extractants. This is because the presence of dialdehyde in the 2-hydroxyarylaldehyde intermediate gives harmful impurities in the final product.

The process of the invention is preferably carried out in a substantially non-polar anhydrous (dry) medium, preferably an aromatic medium. Suitable non-polar liquids are benzene, toluene, xylene, mesitylene, cumene, cymene, tetralin, anisole and chlorinated aromatic hydrocarbons (eg monochlorobenzene, orthodichlorobenzene). Toluene and xylene are particularly preferred solvents.

The group R in the formula Sn (OR) ₄ is preferably an aryl group or an alkyl group and is a residue of a phenol compound involved in the reaction of the present invention or a residue of methanol which is a by-product of the reaction of the present invention. Is preferred. Such tin compounds are conveniently obtained, for example, by reacting tin chlorides, oxides, hydroxides, acetylacetonates and nitrates with a phenol compound or methanol, preferably in the presence of anhydrous alkali. Can be manufactured. Tin tetrachloride (tin chloride) is a particularly preferred starting material. The reaction is conveniently carried out in the solvent which is to be used for the reaction of formaldehyde with the phenol compound. Suitably an excess of phenolic compound is used over that required to form the compound Sn (OR) ₄ . If desired, the phenol compound excess may correspond to that required for the reaction with formaldehyde according to the invention. Suitable alkalis are hydrides, hydroxides, oxides, alkoxides or phenoxides of alkali and alkaline earth metals.

The tin composition used in the method of the present invention has an aqueous medium of 6-10 when extracted with 1-10 volumes of water.
It is required to have such a pH value. This extraction with water does not form part of the invention,
It should be noted that it is a testing tool to characterize tin compositions. The pH of the resulting aqueous medium can be measured with a pH meter or other suitable device. When a tin compound is made by the reaction of a suitable tin starting material with a phenolic compound or methanol in the presence of an alkali, the mineral acid produced during the reaction is neutralized by the alkali. Therefore,
Adjusting the addition of tin compounds to obtain the desired pH value of the aqueous test solution after water extraction is a simple matter.

The pH of the aqueous medium obtained by water extraction is preferably approximately neutral, eg 6-7.5.

The proportion of tin composition is 100% (substituted) phenol compound.
It is preferably such that there is 1.5 to 5 moles of tin per mole. If desired, the proportion of the tin composition may be higher, but it is not of particular benefit. The proportion of tin composition is 1.
It has been found that below 5 mol tin, the selectivity of the reaction for the desired product may be reduced.
A proportion of the tin composition such that about 2 to about 3 moles of tin are present per 100 moles of (substituted) phenol is particularly preferred.

The tertiary amine can be represented by the general formula NR ₁ R ₂ R ₃ , where R ₁ , R ₂ and R ₃ can be the same or different and are preferably alkyl groups. Preferably,
The total number of carbon atoms contained in R ₁ , R ₂ and R ₃ is 30
It is the following. Suitably R ₁ , R ₂ and R ₃ are the same and are preferably lower alkyl groups containing 1 to 3 carbon atoms. For example, a tertiary amine containing such a lower alkyl group, as compared to a tertiary amine containing an n-octyl group,
It was found that a faster reaction was achieved with amines.
Tertiary amines, which also contain lower alkyl groups, are more easily removed from the reaction mixture by conventional means such as distillation.

It is preferred to use 1 to 20 moles of tertiary amine per mole of tin in the catalyst. It has been found that using more than about 3 moles of tertiary amine per mole of tin in the catalyst results in improved selectivity to the desired product (reduction of tar content). There is no particular benefit to using more than about 8 moles of tertiary amine per mole of tin in the catalyst.

The acceleration of the reaction of the process according to the invention with amines is expected in contrast to the above-mentioned report in which the formylation of phenols and the dehydrogenation of hydroxymethylphenols with tin phenoxide as catalyst are hindered and suppressed by free amines. It's outside.

The invention is further described by the following examples ("parts" and "%" are by weight unless otherwise indicated).

Example 1 (a) Invention 4-Nonylphenol (22 g, 100 mmol) and potassium hydroxide (10 mmol) were added to toluene (175 m).
Azeotroped in l) until dry (overnight). When cooled to room temperature, stannous chloride (2.5 mmol) was added and a portion of the product had a pH of 6.5 when extracted with water.
I tried to become. Commercially available tri-n-octylamine (10 mmol) was added. The volume of the reaction mixture was brought to 250 ml with dry toluene and the mixture was stirred under nitrogen for 30 minutes. Paraformaldehyde (9 g, 300 mmol) was then added, the temperature was raised to 100 ° C. and kept at this temperature for 22 hours. IR analysis of the reaction mixture at the end of this time revealed that the mixture was 67.5 mmol 5-nonylsalicylaldehyde and 35 mmol unreacted 4-.
It was shown to contain nonylphenol. The amount of dialdehyde was too low to be accurately determined by GLC analysis and was therefore less than 2% of the product.

Conventional IR techniques have limitations in determining absolute concentrations, such as those needed to calculate selectivity to desired products. The main reaction by-product that determines the selectivity is tar. Therefore, the tar formation concentration was measured by differential thermal analysis (DTA). 33% (5-nonylsalicylaldehyde, 4-nonylphenol and tar) of the solvent-free reaction residue was non-volatile.

(b) Comparative experiment The procedure of (a) above was repeated without using potassium hydroxide, and the general experimental conditions used in the experiment shown in JCS (Perkin I, 1980, page 1862, Table 1) were repeated. Simulated. When a portion of the tin composition is extracted with water, its pH
The value was 7.5. An IR analysis of the reaction mixture at the end of the 22 hour reaction showed only 17.5 mmol of 5-nonylsalicylaldehyde and 47.5 mmol of unreacted 4-.
The presence of nonylphenol was indicated. DTA analysis showed that 47.3% of the solvent-free reaction residue was non-volatile.

These results show that much higher yields and selectivities are obtained with the process of the invention as compared to the prior art process when using an acceptable low concentration of tin catalyst.

(c) Comparative experiment The procedure of (a) above was repeated, but without using tri-n-octylamine. IR of reaction mixture at the end of reaction time
Analysis showed that the reaction mixture contained 24.5 mmol of 5-nonylsalicylaldehyde and 31.5 mmol of unreacted 4-nonylphenol. It is clear that the yield of the desired product is low.

Example 2 4-Nonylphenol (1100 g, 5 mol) and potassium hydroxide (112.2 g, 2 mol) were added to toluene (300 g) and azeotroped under nitrogen until dry. When cooled to 124 ° C, stannic chloride (125.1 g, 0.48 mol) was added over 44 minutes. 15 minutes after the completion of the addition of stannic chloride, remove a 10 ml sample of the solution,
It was extracted by shaking with 50 ml of deionized water. The pH of the aqueous medium after separating the phases was 6.9 as measured by a pH meter. 60 minutes after the addition of stannic chloride, another sample of the solution was taken out and extracted with water, the pH of the aqueous medium was 7.
It was 0. This indicated that the formation of the tin composition was complete.

After cooling to 80 ° C., triethylamine (303 g, 3.0 mol) was added over 6 minutes. The clear reddish brown liquid product was cooled and dried with toluene to give 2 kg of catalyst solution.

A continuous 5-nonylsalicylaldehyde preparation experiment was conducted using a portion of the catalyst solution prepared as described above. 8
To 0 g of catalyst solution was added an additional amount of nonylphenol (132 g) and the solution was made up to 1 with an additional amount of dry toluene (681.2 g). Paraformaldehyde (7
2 g) was added and the mixture was heated to 98-101 ° C. with partial top removal using a water cooled condenser, at which time nitrogen was passed through the reaction mixture at a flow rate of about 80 ml / min. After 6 hours, a sample of the reaction mixture was analyzed by high pressure liquid chromatography (HPLC),
It contained 1.4% unreacted nonylphenol and 14.6% 5-nonylsalicylaldehyde.

Claims (8)

[Claims] 1. A method comprising (i) a tertiary amine and (ii) one or more compounds of the formula Sn (OR) ₄ (where R is an organic group) and extracted with 1 to 10 volumes of water. A tin compound in which the aqueous medium obtained thereby has a pH value of 6 to 10, in the presence of a catalyst consisting of formaldehyde in an anhydrous medium without a substituent at the 2-position. A method for producing a hydroxyaryl aldehyde, which comprises reacting with 2. The method according to claim 1, wherein the group R is an aryl group which is a residue of a phenol compound participating in the reaction or an alkyl group which is a residue of methanol. 3. The phenol compound has an alkyl group of 5 to 2
A process according to claim 1 which is a 4-alkylphenol containing 0 carbon atoms. 4. The method according to claim 1, wherein the formaldehyde is in the form of a polymer. 5. The method according to claim 1, wherein the formaldehyde is paraformaldehyde. 6. The method of claim 1 wherein the tertiary amine is tri-n-octylamine. 7. A tin composition prepared from tin tetrachloride and an excess of a phenolic compound in a solvent, the solvent being used for the reaction of formaldehyde with an excess of the phenolic compound. The method described in. 8. The method according to claim 1, wherein the solvent is toluene or xylene.