DE2201897A1 - Production of o-chlorophenols - Google Patents

Description

IBCRLlNU SMONCHIHtT Dr.-lng. HANS RUSCHKE fiST / S? ' Dipl.-Ing. HEINZAGULAR _raMpmt «, gin · PATENT LAWYERS Tatar · «· -

The Quaker Oats Company, Barrington, Illinois, V.St.v.A.

Production of ^ -chlorophenols

The invention relates to the dehydrochlorination of 2,2,6-FRI chlorocyclohexanone and 2,2,6,6-Tetrachlorcyclohexanon in the presence of from amines, amides, ureas, and acid salts thereof selected catalyst.

Up to now, isoraereine o-chlorine-substituted phenols have not been easily accessible . E-ChlorophenoI is generally made by two processes : (1) chlorination of phenol or (2) hydrolysis of E-dichlorobenzene. 2,6-dichlorophenol can be produced by chlorinating o-chlorophenol.

2-chlorophenol was produced economically, for example by direct chlorination of molten phenol at temperatures between 50 ° and 150 ⁰ C. This process has two major disadvantages: (1) the ratio of chlorine must be carefully controlled to allow the formation of di- and tri-substituted products

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avoid; and (2) m- and ε -chlorophenol are also formed Considerable effort has been made to develop conditions that favor o-substitution; however, no easy way was found. The procedure of The technique for producing o-chlorophenol by the chlorination of phenol therefore has the disadvantage that it is poor in specificity the reaction is present, i.e. the chlorination also in m- and £ - Position takes place as in the o-position, and could lead to more highly chlorinated phenols.

Various processes have been proposed for the partial hydrolysis of ε-dichlorobenzene into ε -chlorophenol. The hydrolysis may be in the vapor phase with water vapor and finely divided silicates, bauxite and magnesite at 500-700 ⁰ C or carried out in aqueous methanol or ethanol at high pressures and remperaturen in the presence of alkali, alkaline earth or alkali metal carbonates. Both of these processes require precise control in order to avoid complete hydrolysis to ε-dihydroxybenzene. The hydrolysis can also require a comparatively long reaction time, for example 30 to 90 minutes.

Mixtures of 2,4- and 2,6-dichlorophenol are usually called Dichlorophenol product obtained in manufacturing processes designed to make the 2,6 isomer. For example if one tries to produce 2,6-dichlorophenol by chlorinating C) -chlorpbenol in a non-polar solvent medium Ilen, the phenolic product obtained is a mixture containing 2,6-dichlorophenol and 2,4-dichlorophenol and small amounts of Contains trichlorophenols and unreacted o-chlorophenol. The separation of isomerically pure 2,6-dichlorophenol from such a Mixing by conventional methods is difficult and troublesome. Effective separation of these isomers by distillation is usually inapplicable because of their close proximity Boiling points. Separation by fractional crystallization is also not applicable because of the similar properties of these compounds.

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22018 «*? ^ -

O. K. Hassel and Lunde describe in Acta Chemica Scandinavica 4, 200-204 (1950) the pyrolysis of 2,2,6,6-Tetrachlorcyclohexanon at 260-270 ⁰ C in the absence of a catalyst. Incumbent is probably the product of the process isomerically pure 2,6-dichlorophenol described above, the yield is low.

In view of the shortcomings of the above processes, there remains a need for an economical, simple process for the preparation of isomerically pure ci-chloro substituted phenols in high yields. Such a method has not previously been taught or suggested anywhere.

The invention relates to a process for the preparation of isomerically pure o-chloro-substituted phenols in high yields from masses of the general formula:

Eq

ci-Ί | ^s x

CH ₂

wherein X is a hydrogen or chlorine radical.

The present invention proposes a process for the preparation of an o-chlorinated phenol, which is characterized in that a chlorinated alicyclic ketone of the general formula: *

2 ⁰ ^ O y ι "* I. CH ₂ , GH Cl ^ c Cl H

Eq

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in which X is a hydrogen or chlorine radical, with a nitrogen-containing catalyst which is an amine, amide, urea or acid salt thereof, at a temperature between 100 and 250 ⁰ G in contact.

Chlorinated alicyclic ketones which can be used in the process according to the invention are 2,2,6-trichlorocyclohexanone and 2,2,6,6-tetrachlorocyclohexanone. 2,2, b, 6-ietrachl or cyclohexanone is produced by generally known processes. 2,2,6-Trichlorocyclohexanone is produced, for example, by adding 475 g of chlorine under essentially anhydrous conditions to 240 ml of carbon tetrachloride and T-> 6 g of cyclohexanone at 15 to JO ⁰ C. Under essentially anhydrous conditions, it is assumed that not more than 1% by weight of water, based on the weight of the cyclohexanone, is present in the reaction mixture and preferably not more than 0.5% by weight of water.

In detail, the amines, amides and ureas which can be used as catalysts have the following general formula:

K-

where η is the integer 1 or 2; K ^ is an alkyl, aryl, aeyl or aroyl group when η = 1 and R ,, is a carboxyl group when η * 2; and R ₀ and R ₃ , independently of one another, represent either a hydrogen group or an alkyl group, ether-aromatic amines can also be used as catalysts. Suitable aromatic amines are, for example, aniline and ia'thylaniliri. Suitable aliphatic amines are, for example, n-butylamine, t-butylamine, di-n-pro] \ ylamJn and; ri-n-tiut, vlamin. Geei.;: U> t ο heteroaromatic amine catalysts are, for example, collidine, pyridine, quinoline, lutidine, I'icoJine and l'yrazine. Suitable ai "ine are, for example!« 'Ormauiid, N, iN-Ui me thy Lacetauud, N, K-' diethylacetiimid, N, IJ-Dimothylpropa onaiin d and w , N-Di a thy 1 prep ι oii-

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amide. Suitable ureas are, for example, urea, tetramethylurea, Tetraethyl urea, dimethyl diethy urea, Konomethyltriethylurea, Trimethyläthylharnstolf and 2-lnidazolidone.

The dehydrochlorination is also carried out in the presence of oüure salts of the above nitrogen-containing catalyst carried out. Suitable Acids are both inorganic and organic acids such as hydrochloric acid and acetic acid.

The reaction can either be continuous or batch and under a given nitrogen or other gas atmosphere, which do not affect the reaction.

At room temperature, <L ', 2, fJ-'L'richlorocyclohexanone is a fluid. ^^, bjG-i'etrachlorcycJohexctnon must be heated above room temperature in order to bring it to the liquid state. The melting point of rej nem t., Ei , ^, 6-Te trachlorcyc lohexanone is b'd - öj C, but is lowered by the presence of a catalyst or impurities.

when executing dor · Lhjhyürocnlori erunr, hovor ;; u,; L, dar. liquid chlorinated cilicyc.liscne k>; tiin with ei non ;; t, ίοκι; liofL'lial ti ( ^ν υη catalyst or kjalz of the same to mi already and continuously passed through a reaction zone kept at a temperature between 100 ° C. and 300 ° C. It is not important that the catalyst is first mixed with a chlorinated alicyclic ketone and is then introduced into the keaklioruizone; the chlorinated alicyclic ketone can first be heated to a temperature between 100 ⁰ and G 2%) ⁰ G are heated and then contacted with a catalyst in the dom Roaktionszone in horiihrung.

UOi increase the yield of _o - '/ hlorpht; nol maxi-inal ^ u and restrict the NeLunroaktionspX'Odukte to oil η minimum if the chlorinated alicyclic ketone ,' ,. ',', - I'm ch i orc. yc I ohexauon is (JH prefers the contact, at a ¹ licaK ti 0: 1:.; Lei. temperature of

BAD ORK31NAL 209836 / 1U8 _Λ ^ ·.;> 0 W

2201 * 97

about 150 ° C to 200 ⁰ C to allow. In order to increase the yield of 2,6-dichlorophenol at a maximum when the chlorinated alicyclic '■ cyclic ketone 2,2,6,6-Tetrachlorcyclohexanon is, it is preferred that the contact at a temperature between about 180 ⁰ C and 225 ⁰ C to run.

The amount of catalyst is not critical. Although the amount of catalyst does not increase the yield of ^ -chlorinated phenol, it affects the rate of dehydrochlorination. It has been found that at least 0.1 wt .-% catalyst, based on the weight of the chlorinated alicyclic ketone, with should preferably be brought into contact with the ketone in the reaction zone. It is also preferred that no more than 10 wt .- ^ o catalyst are present. Although more than 10 wt .-> & Catalyst can be used, this is considered uneconomical to watch.

The contact or reaction time in the reaction zone will vary somewhat with temperature, chlorinated alicyclic ketone, catalyst, and the like. In detail, the necessary reaction time is reduced both by a higher temperature and a higher use of catalyst. Contact times of about 5 seconds to 10 hiriuteri in the presence of about c. Wt .- ^ j catalyst at about 150 ⁰ C to 225 ⁰ C have proven to be satisfactory. The preferred contact time when the chlorinated alicyclic ketone is 2,2,6-trichlorocyclohexanori varies from about 15 seconds to about 3 minutes when the temperature is about 175 ° C. The preferred contact time is about 5> 0 seconds to 5 minutes when 2,2,6,6-tetrachlorocyclohexanone is the chlorinated alicyclic ketone and the temperature is about 200G. It is preferred that the chlorinated alicyoiiyche ketone with the catalyst in the reaction zone not voids, as to bring about a substantial hydrochlorination. ;; necessary to stay in touch. Longer reaction times can lead to possible side reaction products. From the above it is understandable that, according to the invention, comparatively short reactions

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times are preferred.

It is preferred that the dehydrochlorination be carried out under substantially anhydrous conditions. Every 2-chlorophenol or 2,6-dichlorophenol which are formed in the dehydrochlorination reaction, two Ι · ιθ1 hydrogen chloride are formed. This by-product may cause side reactions in the presence of water or other solvolysis h. It is therefore preferred to carry out the reaction in a dry, inert atmosphere. Essentially anhydrous is to be understood as meaning that not more than 1% by weight, based on the weight of the chlorinated alicyclic ketone, is present in the reaction mixture, and preferably not more than 0.5% by weight; t? Water.

The product of the process described above contains catalyst, but no separation is required for many purposes. If necessary, the product can be prepared according to conventional procedures cleaned, preferably by recrystallization.

The following preferred embodiments of the invention serve for the purpose of explaining the invention and illustrating the best mode for carrying out the invention.

example 1

A series of dehydrochlorination reactions was carried out, in which the chlorinated alicyclic ketone is 2,2,6,6-tetrachlorocyclohexanone and the catalyst was selected from various amines, amides, ureas and salts thereof became. The type of catalyst used in each test is given in Table I.

The following procedure was followed in that tent: 25 g of 2,2,6,6-tetrechlorocyclohoxanone and 0.1 g of catalyst were broken into a small tea tube fitted with a condenser. Da3 reactionügemir, ch j η dem Kohr was Λ) I'.i utes

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200 ⁰ G heated, after which the heat source was removed and the tube was allowed to cool for 5 minutes. Then 5 ml of tetrahydrofuran was added to the reaction mixture, and the solution was analyzed by vapor phase chromatography. The relative percentages by weight of 2,6-dichlorophenol and 2,2,6,6-tetr.achlorocyclohexanone, as determined by vapor phase chromatography analysis, are given in Table I.

Table I.

Relative wt .- ^ - compound (vapor phase chromatography-Anal.yse)

2,6-dichloro-2,2,6,6-tetrachloro test catalyst phenol cyclohexanone

1 no 14 86

2 pyridine 100 0

5 Collidine hydrochloride 9 ^ 6

1 51

6 dimethylacetamide 100 0 7

9 Di-n-propylamine 83 17

10 tri-n-butylanine 100 0

11 diethylaniline 100 0

Example 2

25 S 2,2,6-trichlorocyclohexanone, the 0 _t ;; ρ containing collidine hydrochloride were placed in a dropping funnel right above. The dropping funnel was placed on a 100 ml three-volume flask, which was also equipped with a gas outlet and stirrer. The flask was kept at 200 ° C while the ketone I; uif; c; m was dripped into the flask over a period of .JC to 50 minutes.

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no 14th Pyridine 100 Collidine hydrochloride 94 Tetramethylurea 99 Formamide 49 Dimethylacetamide 100 n-butylamine 74 t; -butylamine 49 Di-n-propylamine 83 Tri-n-butylanine 100 Diethylaniline 100

The product of the above reaction was then reduced under reduced Pressure (40 mm) distilled and gave 14 g (8? Wt. Ifc) o-chlorophenol.

Example 3

Following the procedure from Example 2, 25 g of 2, ^, 6, o-tetrachlorocyclohexanone containing 0.5 g of collidine hydrochloride were used and gave 15.6 g (90% by weight / b) of 2,6-dichlorophenol which melted at 64 - 65 ^{° C.}

Example 4

The following procedure was followed: 281.8 g 2,2,6,6 ^r I'etrachlorcyclohexanon and 5 "6 g collidine hydrochloride were placed in a dropping funnel. The dropping funnel was heated by a heating lamp until the 2,2,6,6-tetrachlorocyclohexanone was liquid.

The 2,2,6,6-tetrachlorocyclohexanone containing the catalyst was purged with nitrogen and added dropwise to a 60.6 cm column (2.22 cm outer diameter; 1.4-3 cm inner diameter) filled with glass beads of 4 mm diameter was packed. ^{The packed column was heated to 200 °} C. along its entire length by means of an electric tube furnace.

The dehydrochlorination was continued for 1 1/2 hours, ge run until hurried 2,2,6,6-Tetrachlorcyclohexanon by the heating column, and was converted to product. The dehydrochlorinated gelatin was recovered and the mixture was ^{distilled under reduced pressure (1} K). The recovered product was distilled ε 177 (91 parts by weight ίΐί) of 2,6-dichlorophenol, having a melting point of 64 - 65 showed ⁰ C.

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- ίο -

Example 3

Following the procedure from Example 4, but omitting of the addition funnel heating step, 165.4 g 2,2,6-trichlorocyclohexanone instead of 2,2,6,6-tetrachlorocyclohexanone dehydrochlorinated in the presence of 2.5 g of collidine hydrochloride. The distilled product was 97 g (91 wt. #) 2-chlorophenol.

The above examples clearly demonstrate the practice of this invention. In Example 1 it is demonstrated that amines, amides, Urea and salts thereof, the dehydrochlorination of 2,2,6,6-1'etrachlorocyclohexanone to isomerically pure 2,6-dichlorophenol support financially. Test 1 is not within the scope of the invention, but has been used as an example of a method in which a catalyst is not used. It should be emphasized that no other dichlorophenol isomer is formed. example 1 is also an example of a batch approach.

Examples 2 and 3 further illustrate the invention. In Example 2, 2,2,6-trichlorocyclohexanone is converted to o-chlorophenol in 875% yield . Yield "dehydrochlorinated · In Example 3, the 2,2,6,6-Tetrachlorcyclohexanon to 2,6-Üichlorphenol is in 9O

Examples 4 and 5 are illustrations for continuous processes · In Example 4, a continuous method is described for the dehydrochlorination of 2,2,6,6-tetrachloro cyclohexanone. Example 5 describes a continuous process for the dehydrochlorination of 2,2,6-frichlorocyclohexaneQn .

Claims

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Claims (8)

- 11 - Claims A process for preparing a 2- ^cn l ° ^r i ^{he "t; en} phenol, as characterized by reacting a chlorinated alicyclischea ketone of the general formula Il Cl / \ Cl "c c ' he 'ι i ^ x CHp CH ₂ wherein X is a hydrogen or chlorine radical, with a nitrogen-containing catalyst which is an amine, amide, urea, or acid salt thereof, brings at a temperature between 100 and 250 ⁰ C in contact. 2. The method according to claim 1, characterized in that aass more than 0.1 wt .-%, based on the weight of the chlorinated alicyclic Ketones, from this nitrogenous catalyst are present. ' 3 · The method of claim 1, characterized in that 0.1 wt .- ^ 6 of the nitrogen-containing catalyst, based on the weight of the chlorinated alicyclic ketone to 10 wt -.% Are present of the catalyst. 4. The method of claim 1, 2 or 3, characterized in that the chlorinated alicyclic ketone Trichlorcyclo- 2,2,6-hexanone and the contact is carried out at a reaction temperature of about 0 to 200 ^ 1 ⁰ C. 209836/1 1 5. The method of claim 1, 2 or 3, characterized in that the chlorinated alicyclic ketone 2,2,6,6-Tetrachlorcyclohexanon is carried out and the contact at a temperature of about ⁰ C to 225 1ÖO. 6. The method according to any one of the preceding claims, characterized characterized in that the contact in a continuous introduction of the nitrogen-containing catalyst containing chlorinated alicyclic ketone in an inert atmosphere through a reaction zone based on said Reaction temperature is maintained. 7 · Method according to one of the preceding claims, characterized characterized in that the nitrogen-containing catalyst is a heteroarotnatic amine, aromatic amine, aliphatic Amine, N-alkyl-substituted amide, H-aryl-substituted amide, N-alkyl substituted urea, N-aryl substituted urea or acid salt thereof. 8. The method according to claim 7, characterized in that the heteroaromatic amine catalyst collidine and the acid salt of the same is gollidin hydrochloride. 9 · The method according to claim 7 »characterized in that the aliphatic amine is tri-n-butylamine. Dr.Pa/He 209836 / 11A8