FR2585016A1 - LIQUID PHASE DEHYDRATION PROCESS OF AROMATIC ALCOHOL - Google Patents

Abstract

A PROCESS FOR DEHYDRATION IN THE LIQUID PHASE OF AN AROMATIC ALCOHOL REPRESENTED BY FORMULA I: (CF DRAWING IN BOPI) IN WHICH AR REPRESENTS A PHENYL, 1-NAPHTYL OR 2-NAPHTYL GROUP AND R REPRESENTS A HYDROGENE ATTRIBUTES OR A METHYL GROUP, THE PROCESS INCLUDING THE HEATING OF THE AROMATIC ALCOHOL REPRESENTED BY FORMULA I IN THE PRESENCE OF A SOLID ACID CATALYST, THUS CONVERTING THE AROMATIC ALCOHOL INTO THE CORRESPONDING AROMATIC VINYL COMPOUND.

Description

Process for the dehydration in the liquid phase of an aromatic alcohol La

  The present invention relates to a process

  dehydration in the liquid phase of an aromatic alcohol

  tick represented by formula (I): CH3

I

Ar-C-OH (I) I R

  wherein Ar is phenyl, 1-naphthyl

  tyl or 2-naphthyl and R represents a hydrogen atom

or a methyl group.

  The synthesis of an olefin by dehydration of an alcohol is well known, and in the dehydration carried out in the liquid phase, sulfuric acid, phosphoric acid and a mixture of zinc chloride and hydrochloric acid are used as catalysts while that in the dehydration carried out in the gas phase, a

  solid acid like alumina is used as a catalyst

  lyst. In the case where an aromatic alcohol represented by the formula (I): CH 3 Ar-C-OH (I)

I

  In which Ar and R are as defined above, respectively, must be dehydrated to be converted to the aromatic vinyl compound represented by the formula (II): ## STR1 ## wherein Ar and R are respectively as defined above, in the liquid phase in the presence of sulfuric acid, phosphoric acid or zinc chloride hydrochloric acid, such as the cyclized dimer by-product of the formula (III):

R CH3

  Ar 't (III) R Ar in which Ar and R are as defined above and Ar' represents a divalent aromatic residual group derived from Ar, is produced in a notable manner, the compound can not be obtained with a favorable yield. aromatic vinyl represented by

formula (II).

  The aromatic vinyl compound represented by the formula (II) is useful as a monomer for producing high polymers and therefore it is necessary to produce the compound on an industrial scale from the alcohol.

  aromatic represented by the formula (I). In particular

  like the high-boiling vinyl compound

  such as 2-isopropenylnaphthalene

Formula (IV): CH3

3H2 (IV)

  It is capable of improving the heat resistance of an ABS resin, as described in Japanese Unexamined Patent Application Publication (KOKAI) No. 58-108244 (1983), the process being in accordance with to the present invention is

  particularly useful for producing on an industrial scale

  such high-boiling vinyl compounds

  lition. In this connection, the aromatic alcohol represented by the formula (I) can be produced by oxidation of

  the corresponding hydrocarbon by molecular oxygen

  or air in the presence of an aqueous alkaline solution. Given the situation mentioned above, the applicant has sought to develop a process for dehydrating the aromatic alcohol represented by the formula (I) with an interesting selectivity, for the

  convert to an aromatic vinyl compound

  Formula (II), and following its studies, the applicant has found that the aromatic compound represented by formula (II) (hereinafter referred to as compound (II)) can be obtained with a yield

  favorable by submission of the aromatic alcohol represented

  characterized by the formula (I) (hereinafter referred to as the compound (I)) being dehydrated in the liquid phase using no solvent or in a solvent in the presence of a solid acid retaining the catalyst, and from this discovery , the plaintiff realized this

invention.

  It is therefore an object of the present invention to provide a process for dehydrating the compound (I) in the liquid phase, wherein the compound (I) is heated in the presence of a solid acid catalyst to convert the

compound (I) to compound (II).

  According to one aspect of the present invention, there is provided a method of liquid-phase dehydration of an aromatic alcohol, comprising heating an aromatic alcohol represented by the formula (I): CH3 I ArC-OH (I)

R

  wherein Ar is phenyl, 1-naphthyl

  tyl or 2-naphthyl and R represents a hydrogen atom or a methyl group, in the presence of an acid catalyst

  solid, thereby converting the aromatic alcohol represented

  characterized by the formula (I) to an aromatic vinyl compound represented by the formula (II): ## STR1 ## wherein Ar and R are respectively such that

defined above.

  In the process according to the present invention,

  The compound (I) is reacted without the use of a solvent or in a solvent using a solid acid.

as a catalyst.

  In fact, in the process according to the present

  invention, the use of a solvent is not necessary.

  however, it is preferable to use a solvent to control the reaction temperature. It is possible to use, for example, hexane, heptane, benzene, toluene or

  xylene, preferably toluene or xylene.

  In addition, an aromatic hydrocarbon can be used.

  which is a raw material for the production of the compound (I), as a solvent for the dehydration reaction. For example, 2isopropylnaphthalene can be used as a solvent in dehydration

2- (2-naphthyl) -2-propanol.

  In addition, in the case where a solvent having a boiling point higher than that of the dehydration product is chosen, the use of such a solvent is advantageous because the reaction product can be separated by distillation of the solvent. For example, in the

  case of the production of α-methylstyrene, the 2-iso-

  propylnaphthalene is suitable as a solvent in the reaction

  and in the case of the production of 2-isopropenylnaphthalene

  lene, 2,6-diisopropylnaphthalene, 2,7-diisopropyl-

  naphthalene or a mixture of 2,6- and 2,7-diisopropyl naphthalene

  talene are suitable as the solvent in the reaction.

  When carrying out the process according to

  In the present invention, the solvent is used in a

  from 0.5 to 20 times by volume, preferably from 1 to 10 times by volume, relative to the weight of the raw material. In carrying out the process according to the present invention, a solid acid composed mainly of a mixed oxide of silicon and aluminum is used as the catalyst. Although a solid acid catalyst such as aluminum silicate, diatomite, active terra alba, synthetic zeolite type H and the like are suitable for the process of the present invention,

  in accordance with the plaintiff's discovery, the

  relative increase in dehydration and dimeri-

  is determined by the density of what is called Broensted acid on the surface of the catalyst

solid acid.

  In fact, in the case where the catalyst having a high density of Broensted acid is used, the dehydration takes place mainly and on the other hand, in the case where the catalyst having a low

  Broensted acid density is used, the dimerization

  tion takes place mainly. An aluminum silicate and an H type synthetic zeolite whose density

  Broensted acid is particularly suitable

  primarily as a catalyst used in the process of

present invention.

  When carrying out the process according to the present invention, the amount of catalyst is 0.1 to 20% by weight, preferably 0.5 to 10% by weight, of the amount of raw material. To carry out the process according to the present invention, the compound (I) is mixed with the solid acid catalyst, the solvent is also mixed if necessary and the mixture is heated with stirring at 50.degree.-300.degree. at 100-200 ° C, for one minute to 2 hours, preferably for 2 minutes to one hour. When the reaction is complete, the catalyst can be removed from the reaction mixture simply by filtration. The process of the present invention has an important feature that removal of the catalyst from the reaction mixture is extremely easy. The present invention is further explained in detail with reference to non-limiting examples and

following comparison examples.

Example 1

  1.072 g (7.87 mmol) of 2-phenylpropionic acid was

  2-propanol in 10.7 ml of xylene and, while stirring and heating the solution to 140 ° C, was introduced into the solution 10.7 g of aluminum silicate (manufactured by SOEKAWA RIKAGAKU Co., Ltd., Al203.3SiO2) and reacts

  the mixture such as for 20 minutes.

  By examining the reaction mixture by chroma-

  thin film (on a silica gel made

  by Merck, HPTLC 5628, with an eluent comprising a hexane / ethyl acetate solvent mixture = 200/1),

  found that the starting material, 2-phenyl-2-

  propanol, had completely disappeared and only amethylstyrene was formed and not at all dimer -7

  cyclized. Analysis of the reaction product by chromato-

  Gas phase graphing with 2-acetonaphthon as an internal reference indicated that the amount of α-methylstyrene thus formed was 0.879 g (7.44 mmol, 94.5% yield).

Comparative Example 1

  1,041 g (7.64 mmol) of 2-phenyl

  2-propanol in 10.4 ml of xylene and, with stirring and heating the solution to 140 ° C, was added to the solution 0.1 ml of concentrated sulfuric acid, then

  allowed to react the mixture such that for 10 minutes.

  By studying the reaction mixture by

  thin film, it has been found that the

  raw material, 2-phenyl-2-propanol, had

  disappeared, that a compound with a polarity slightly higher than that of α-methylstyrene had been formed, and that t-methylstyrene

hardly trained.

  It has been assumed that part of the main product

  isolated from the reaction mixture by chromato-

  Column scan was the next cyclized dimer, based on the results from its nuclear magnetic resonance spectrum and mass spectrum:

CH3 CH3

  3O Value 6 on NMR (250 MHz, in CDCl3) 1.36 (3H, s) 1.40 (3H, s) 2.02 (3H, s) 2.24 (1H, d) 2.36 (1H, d) 7.0 to 7.4 (9H, m) Mass Spectrum Data (DI, 70 eV) m / e: 236 and 221.

Example 2

  A mixture of 253.4 mg (1.36 mmol) of 2- (2-naphthyl) -2-propanol and 2.5 ml of xylene was heated to 140 ° C with stirring and 2.5 mg of sodium silicate added. aluminum (the same as in Example 1) to the mixture in which a portion of the raw material was not dissolved, then reacting any mixture for 15 minutes. After cooling the reaction mixture, the aluminum silicate was removed by filtration and the solvent was distilled off the filtrate. The residue was subjected to purification by column chromatography (the column being a Merck LOBAR-B column (Trade Mark) and the eluent being a 200: 1 mixture of hexane and ethyl acetate) to obtain 213 , 6 mg (1.27 mmol) of 2-isopropenylnaphthalene

pure with a yield of 93.3%.

Comparative Example 2

  A mixture of 113.4 mg (0.609 mmol) of 2- (2-naphthyl) -2-propanol and 1 ml of xylene was heated to 140 ° C with stirring and while stirring the mixture was added to it. 0.02 ml of concentrated sulfuric acid and reacts the whole mixture such that for 10 minutes. Following the examination of the reaction product

  by thin layer chromatography, the

  complete appearance of the raw material, 2- (2-naphthalene)

  tyl) -2-propanol of the reaction mixture, it was found that 2isopropenylnaphthalene was barely detected in this mixture and that the cyclized dimer was the main product. Purifying the reaction product by the same column chromatography as used in Example 2 gave 93.5 mg -A

  (0.278 mmol) of the following cyclized dimer with a

91.3%.

CH3 CH3

  Value 6 on NMR (250 MHz, in CDCl3) 1.38 (3H, s) 1.42 (3H, s) 2.05 (3H, s) 2.32 (1H, d) 2.44 (1H, d) ) 7.0 to 7.9 (13H, m) Mass Spectrum Data (DI, 70 eV) m / e: 336 and 321.

Example 3

  A mixture of 112.7 mg (0.605 mmol) of 2- (2-naphthyl) -2-propanol and 1 ml of xylene was heated at 110 ° C. with stirring and 11.2 mg of H-type zeolite was added thereto ( manufactured by TOYO Soda Co., Ltd., Brand: TSZ-33OHSA). The entire mixture was reacted for 10 minutes. Studying the reaction mixture

  by gas chromatography, with 2,6-di-

  isopropylnahthalene as internal reference, it was found that 92.3 mg (0.549 mmol) of 2-isopropenylnaphthalene was formed in a yield of 90.7%. It was also found by studying the reaction mixture

  by thin layer chromatography and chromatography

  gas phase, that the raw material had

  completely disappeared from the reaction mixture.

Comparative Example 3

  A mixture of 99.0 mg (0.532 mmol) was heated

2 585016

  2- (2-naphthyl) -2-propanol and 1 ml of OC toluene with stirring and added thereto 8.0 mg of another type H zeolite (prepared by TOYO Soda Co., Ltd .; ., mark: TSZ-330 HUA). The entire mixture was allowed to react for 10 minutes.

  By examining the reaction mixture by chroma-

  gas chromatography with 2,6-diisopropyl-

  naphthalene as an internal reference, it has been found that

  43.2 mg (0.257 mmol) of 2-isopropenyl

  naphthalene with a yield of 45.1%. Thin layer chromatographic and gas chromatographic analysis of the reaction mixture showed that the raw material had completely disappeared from the reaction mixture and the result of thin layer chromatography of the reaction mixture indicated that the dimer cyclized was another product of the reaction. In this regard, the difference in activity between the two type H zeolites, TSZ-33OHSA and TSZ-33OHUA, depends on the difference between their amounts of Broensted acid and their specific surface of the type H zeolite TSZ-33OHSA is the same as that of zeolite type H TSZ-33OHUA. In fact, as TSZ-330HSA is known to have twice as many Broensted acid points as TSZ-33OHUA zeolite, this confirmed that Broensted acid is the source of the selectivity

  vinyl compounds of the present invention.

Example 4

  After mixing 27.6 mg of the same aluminum silicate as used in Example 1 and 2.8 ml of xylene and then heating the mixture to 140C with stirring, 276 was added dropwise to the mixture. 3 mg (2.26 mmol) of 1-phenylethanol and reacted

  all the mixture such as for 30 minutes.

  By studying the reaction mixture by

  gas chromatography with a-methyl-

  styrene as internal reference and by thin layer chromatography, it was found that the raw material had completely disappeared from the reaction mixture and 217 mg (2.8 mmol) of styrene had formed.

  a yield of 92.1% and not at all cyclized dimer.

Example 5

  In a three-necked flask having a capacity of 300 ml, equipped with a stirrer, a gas inlet tube and a reflux condenser, 10.0 g (58.7 mmol) of 2-isopropylnaphthalene were introduced. and 100 g of a 30% aqueous solution of sodium hydroxide and, while heating the substances thus introduced to 85C, molecular oxygen was sent into the flask at a rate of 4.0 liters / hour while vigorously shaking the contents of the container at 500 rpm. The reaction was stopped after 8 hours and, after cooling, the contents of the flask were removed and extracted three times with 10 ml portions of ethyl acetate. The ethyl acetate layers were collected, washed with a 5% aqueous solution of hydrochloric acid and then with saturated aqueous sodium chloride solution and finally dried with anhydrous sodium sulfate. While ethyl acetate was distilled off from the product thus dried, 10.5 g of a pale yellow oil were collected. By studying the composition of the oil thus obtained by gas chromatography with hexamethylbenzene as internal reference, it was found that the oil contained 5.2 g (30.5 mmol with a reaction rate of 48.0%). %) of 2isopropylnaphthalene, 4.5 g (24.2 mmol with a yield of 41.1% and a selectivity of 85.6%) of 2- (2-naphthyl) -2-propanol and 0.33 g (1 , 94 mmol with a yield of 3.3% and a

  selectivity of 6.9%) of 2-acetonaphthon.

  While heating all the oil

  At 140 ° C., a portion of 100 mg of the same aluminum silicate as was described in Example 1 was added three times to the oil. After heating and stirring the oily mixture for 30 minutes and then cooling it, the catalyst (aluminum silicate) was filtered off and the filtrate was analyzed by gas chromatography to find that it had formed

  3.71 g (22.1 mmol) of 2-isopropenylnaphthalene.

  Moreover, in a separate experiment, we were able to

  easily isolate crystals of 2-isopropenylnaphthalate

  from a mixture of 2-isopropylnaphthalene and 2isopropenylnaphthalene, by recrystallization from

  mixture of hexane or methanol.

  In addition, according to the actual measurement, 2-isopropyl-

  naphthalene boils at 118, 129 and 143 ° C respectively at a reduced pressure of 5, 10 and 20 mm Hg, and 2-isopropenylnaphthalene boils at 129, 138 and 154 ° C, respectively, at a reduced pressure of 5, 10 and 20 mm.

  As a consequence, the separation of 2-isopropenylnaph-

  talene can be easily performed by distillation

under reduced pressure.

Claims (12)

  A method of liquid phase dehydration of an aromatic alcohol, comprising heating said aromatic alcohol represented by the formula (I): ## STR2 ##   wherein Ar is phenyl, 1-naphthyl   tyl or 2-naphthyl and R represents a hydrogen atom or a methyl group, in the presence of an acid catalyst   solid, thereby converting the aromatic alcohol represented   compound of the formula (I) into an aromatic vinyl compound   represented by the formula (II): R I Ar - C = CH 2 (I) wherein Ar and R are respectively defined above.   2. The process of claim 1 wherein the solid acid catalyst is aluminum. I) such as 1, in silicate 3. A process according to claim 1, wherein the solid acid catalyst is a type H synthetic zeolite. 4. A process according to claim 1, wherein the amount of solid acid catalyst used in said dehydration is from 0.1 to 20% by weight of the amount of aromatic alcohol.   The process of claim 4 wherein the amount of solid acid catalyst is 0.5.   10% by weight of the amount of aromatic alcohol.   The process of claim 1, wherein the step of heating the aromatic alcohol is carried out in the presence of the solid acid catalyst and a solvent. The process of claim 6 wherein the solvent is at least one kind of solvent selected from the group consisting of hexane, heptane,   benzene, toluene and xylene.   The process according to claim 6, wherein the solvent used is an aromatic hydrocarbon which is the starting material for the production of aromatic alcohol ..   9. The method of claim 8, wherein   wherein the solvent is 2-isopropylnaphthalene.   The process according to claim 6, wherein the solvent used is a solvent which has a boiling point higher than that of the vinyl compound.   aromatic represented by formula (II).   11. The process of claim 10 wherein the solvent is 2isopropylnaphthalene; 2,6-diisopropylnaphthalene; 2,7-diisopropylnaphthalene or a mixture of 2,6-diisopropylnaphthalene and 2,7-diisopropylnaphthalene. The process according to claim 6, wherein the amount of solvent used in this process is 0.5 to 20 times by volume the weight of the alcohol. aromatic.   The process according to claim 12, wherein the amount of solvent used in this process is 1 to 10 times by volume the weight of the aromatic alcohol. The process of claim 1, wherein the heating temperature is in the range of at 300 ° C.   The method of claim 14, wherein the heating temperature is in the range of 100 to 200 ° C.   16. The process of claim 1 wherein the aromatic alcohol is. heated for 1 minute at 2 o'clock.   17. The process of claim 16 wherein the aromatic alcohol is heated for 2 minutes at 1 o'clock.