JPH036128B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for oxidizing m- or -p cresyl acetate. More particularly, the present invention relates to a new process for the oxidation of m- or -p cresyl acetate to ultimately produce equimolar amounts of hydroquinone or resorcinol and formaldehyde or paraformaldehyde. [Prior art] Grozhan et al. Doklady Akad.
From NaukSSSR No. 204 No. 4872 and USSR Patents Nos. 329167 (1972) and 321518 (1971), it is known that when toluene is oxidized in the presence of acetic anhydride and acetic acid and then all reaction products are saponified, substantial It is known that amounts of phenol and with it smaller amounts of benzaldehyde, benzyl acetate and other related substances are produced. Corresponding British Patent No. 1244080, also based on the Soviet Union, teaches a similar process and further describes the mechanism by which phenols and aliphatic aldehydes or ketones are co-formed through the formation and rearrangement of hydroperoxide intermediates. is suggesting. Importantly, the formation of methylene diacetate is neither mentioned nor suggested, and thus clearly there is no teaching of converting said methylene diacetate to formaldehyde. Furthermore,
This Soviet study does not say anything about using any promoters or other auxiliaries besides the acid catalyst that would serve to increase the rate, yield, or selectivity of this oxidation reaction. . [Means for Solving the Problems] A novel method for ultimately producing equimolar amounts of hydroquinone or resorcinol and formaldehyde or paraformaldehyde according to the present invention.
A method of oxidizing p-cresyl acetate is provided. Generally, this is achieved in a manner consisting of the following steps. m- or -p cresyl acetate is oxidized with air or oxygen at selected pressures and temperatures in the liquid phase in the presence of acetic anhydride and a strong acid catalyst to form resorcinol or hydroquinone diacetate and methylene diacetate. Acetate is produced in equal amounts with acetic acid. Methylene diacetate and resorcinol or hydroquinone diacetate are separated by distillation of the reaction products. Resorcinol or hydroquinone diacetate is saponified to produce resorcinol or hydroquinone and acetic acid, and methylene diacetate is pyrolyzed to produce formaldehyde and acetic anhydride. The oxidation stage is further characterized according to the invention by the use of persulfates in order to suppress the unwanted formation of _CO2 . Optionally, these additives may be used simultaneously. Finally, the method increases the yield of the desired product by using certain selected temperatures and pressures. As previously mentioned, the first step of the process is the liquid phase oxidation of m- or -p cresyl acetate using a strong acid catalyst to produce resorcinol or hydroquinone diacetate and methylene diacetate. This reaction is shown as follows. CH ₃ COOPhCH ₃ +O ₂ +2Ac ₂ O ^H ₂ ^SO ₄ →AcOPhOAc
+ CH ₂ (OAc) ₂ + HOAc Here, the weight ratio of toluene to acetic anhydride is approximately
50:1 to 1:10 preferably 10:1 to 2:1
while the use of H ₂ SO ₄ m- or -
The ratio to p-cresyl acetate is approximately 5×10 ⁻⁴
to 1×10 ⁻² and preferably from 1×10 ⁻³ to 5×
It is up to 10 ^-3 . Reactions using oxygen or a significant amount of air are carried out at temperatures ranging from about 140° to 300°C and preferably from about 150° to 250°C, and from about 50 to 450 psig (3.52 to 450 psig).
It should be carried out at an initial pressure of 31.64 Kg/cm ² ). Pressure is preferably created by charging the autoclave with air or an oxygen/nitrogen mixture having an oxygen/nitrogen ratio of 10:1 to 1:20 psig. The reaction mixture is then heated, thereby increasing the reaction pressure. The reaction may be carried out in an excess of m- or -p cresyl acetate as solvent or in an organic solvent such as benzene, chlorobenzene, or acetic acid. Although carrying out the reaction in an inert solvent such as benzene or chlorobenzene has no appreciable effect on yield or selectivity, a significant increase in selectivity is observed when acetic acid is used. To speed up the reaction in acetic acid, a promoter such as dry caroic acid should be used. The reaction product, which contains products such as resorcinol or hydroquinone diacetate and methylene diacetate and smaller amounts of benzyl acetate and benzylidene acetate, is then treated in a routine manner to remove the acid catalyst therefrom. The resorcinol or hydroquinone diacetate and methylene diacetate are then separated by distillation under vacuum. Pyrolysis of methylene diacetate produces formaldehyde and acetic anhydride. This thermal decomposition is conveniently carried out in one step by a homogeneous gas phase reaction at about 450 DEG -550 DEG C. and under reduced pressure. Air may be used in place of _O2 , but in this case the amount is increased proportionately to provide an equivalent amount of _O2 . The acid catalyst is preferably sulfuric acid, but other similar acids such as peroxymonosulfuric acid, Caro acid dry reagent or mixtures thereof can be used instead. If desired, small amounts of initiators such as azobisisobutyronitrile, dibenzoylperoxy, etc. may be added to aid in starting the reaction. Generally 0.2 weight percent is sufficient for this purpose. REFERENCE EXAMPLE The following reference example regarding the conversion of toluene is provided to illustrate the embodiments of the invention described thereafter. Reference Example 1 The following ingredients were charged into a 300 ml rocking autoclave reactor. Toluene 240 mmol Acetic anhydride 120 mmol H ₂ SO ₄ 1 mmol N ₂ 230 psi (16.17 Kg/cm ² ) O ₂ 60 psi (4.218 Kg/cm ² ) Rapidly raise the temperature to 230°C and reduce the temperature to 1
It kept time. At the end of this time rapid cooling was achieved by immersion first in air and then in cold water.
Both gas and liquid phases were then analyzed. Gas phase mass spectrometry and pressure drop measurements were consumed
The ratio of the number of moles of CO ₂ produced to the number of moles of O ₂ is
It was shown that it is 0.21. Standardized gas chromatography analysis of the liquid phase showed that the toluene conversion was 9% and more than 60% of the acetic acid was consumed. Product selectivity (mol%) converted toluene
Based on 100: Phenyl acetate 52 Methylene diacetate 52 O-methylphenylacetate 4 Benzyl acetate 16 Phenoxymethylene acetate 6 Benzylidene diacetate 6 Tar and others 16 (100 moles of toluene yields 52 moles each of phenyl acetate and methylene diacetate) Reference Example 2 The following ingredients were charged into a 300ml rocking autoclave reactor. Toluene 240 mmol Acetic anhydride 120 mmol H ₂ SO ₄ 1 mmol MoO ₃ 0.1 g N ₂ 230 psi (16.17 Kg/cm ² ) O ₂ 60 psi (4.22 Kg/cm ² ) The temperature was rapidly increased to 201°C where 1 It kept time. At the end of this time the product was worked up according to the procedure of Comparative Example 1. The ratio of moles of CO ₂ produced to moles of O ₂ consumed was 0.08. Standardized gas chromatographic analysis of the liquid phase showed toluene conversion to be 10%. Product selectivity (%) converted toluene 100
Based on the following: Phenyl acetate 54 Methylene diacetate 54 O-methyl phenyl acetate 4 Benzyl acetate 15 Phenoxymethylene acetate 6 Benzylidene diacetate 6 Tar and others 15 Reference example 3 The following components were charged into a 300 ml rocking autoclave reactor. . Toluene 240 mmol Acetic anhydride 120 mmol H ₂ SO ₄ 1 mmol MoO ₃ 0.1 g Ni dithiosemicbentyl 0.15 mmol N ₂ 230 psi (16.17 Kg/cm ² ) O ₂ 60 psi (4.22 Kg/cm ² ) Temperature rapidly increased to 203°C and held there for 1 hour. At the end of this time the product was worked up according to the procedure of Comparative Example 1. The ratio of the number of moles of CO ₂ produced to the number of moles of O ₂ consumed was 0.10. Standardized gas chromatography analysis of the liquid phase showed toluene conversion to be 16%. Product selectivity (%) converted toluene 100
Based on this, it was as follows. Phenyl acetate 50 Methylene diacetate 51 O-methylphenylacetate 4 Benzyl acetate 18 Phenoxymethylene acetate 8 Benzylidene diacetate 6 Tar and others 14 The CO ₂ /O ₂ ratio of Reference Example 1 was compared with that of Examples 1 and 2. In comparison, in suppressing CO ₂ production
The effectiveness of MoO ₃ has been clearly demonstrated. Reference Example 4 The following ingredients were charged into a 300 ml rocking autoclave reactor. Toluene 240 mmol Acetic anhydride 120 mmol H ₂ SO ₄ 1 mmol CrO ₂ 0.1g N ₂ 230psi (16.17Kg/cm ² ) O ₂ 60psi (4.22Kg/cm ² ) Rapidly raise the temperature to 202℃ and keep at that temperature for 1 hour I kept it. At the end of this time the product was worked up according to the procedure of Comparative Example 1. The ratio of moles of CO ₂ produced to moles of O ₂ consumed was greater than 0.3. Standardized gas chromatography analysis of the liquid phase showed toluene conversion to be 11%. Product selectivity (%) converted toluene 100
Based on this, it was as follows. Phenyl acetate 20 Methylene diacetate 19 O-methyl phenyl acetate 5 Benzyl acetate 36 Phenoxymethylene acetate 12 Benzylidene diacetate 16 Tar and others 11 Reference example 5 The following components were placed in a 300 ml rocking autoclave reactor. . Toluene 240 mmol Acetic anhydride 120 mmol H ₂ SO ₄ 1 mmol WO ₃ 0.1 g N ₂ 230 psi (16.17 Kg/cm ² ) O ₂ 60 psi (4.22 Kg/cm ² ) The temperature was rapidly raised to 203°C and held there for 1 hour. . At the end of this time the product was worked up according to the procedure of Comparative Example 1. The ratio of moles of CO ₂ produced to moles of O ₂ consumed was 0.25. Standardized gas chromatography analysis of the liquid phase showed a toluene conversion of 8%. Selectivity mole% of product converted toluene
Based on 100%: Phenyl acetate 35 Methylene diacetate 50 O-methylphenylacetate 2 Benzyl acetate 35 Phenoxymethylene acetate 3 Benzylidene diacetate 4 Tar and others 21 Selectivity and reference of Reference Example 2 and Reference Example 3 in which MoO ₃ was used Comparing the results obtained with CrO ₃ and WO ₃ in Examples 4 and 5, for the purpose of obtaining the desired phenyl acetate and methylene diacetate,
It becomes clear that MoO ₃ is significantly superior to these other metals. Furthermore, while MoO ₃ provides a smoothly catalyzed reaction with little combustion to CO ₂ ,
2.5-4.0 times more _CO2 was produced in the case of _CrO3 and _WO3 . Reference Example 6 The following ingredients were charged into a 300 ml rocking autoclave reactor. Toluene 240 mmol Acetic anhydride 120 mmol H ₂ SO ₄ 1 mmol K ₂ S ₂ O ₈ 0.1 g N ₂ 230 psi (16.17 Kg/cm ² ) O ₂ 60 psi (4.22 Kg/cm ² ) The temperature was rapidly raised to 201℃, and here I kept it there for an hour. At the end of this time the product was worked up according to the procedure of Reference Example 1. Standardized gas chromatography analysis of the liquid phase showed toluene conversion to be 16%. Product selectivity (mol%) converted toluene
Based on 100, it was as follows. Phenyl acetate 54 Methylene diacetate 51 O-methyl phenyl acetate 4 Benzyl acetate 15 Phenoxymethylene acetate 6 Benzylidene diacetate 6 Tar and others 15 Reference example 7 The following components were charged into a 300 ml rocking autoclave reactor. . Toluene 240 mmol Acetic anhydride 120 mmol H ₂ SO ₄ 1 mmol Dry Caroic acid 0.5 g N ₂ 230 psi (16.17 Kg/cm ² ) O ₂ 60 psi (4.22 Kg/cm ² ) The temperature was rapidly raised to 203°C and kept for 1 hour. I kept it. At the end of this time the product was worked up according to the procedure of Comparative Example 1. Standardized gas chromatography analysis of the liquid phase showed toluene conversion to be 18%. Product selectivity (%) was as follows based on toluene converted: Phenyl acetate 55 Methylene diacetate 54 O-methyl phenyl acetate 4 Benzyl acetate 13 Phenoxymethylene acetate 6 Benzylidene diacetate 6 Tar and others 16 100 Reference example 8 The following components were charged into a 300 ml rocking autoclave reactor. Ta. Toluene 160 mmol Acetic acid 80 mmol Acetic anhydride 120 mmol Dry Caroic acid 0.5 g N ₂ 230 psi (16.17 Kg/cm ² ) O ₂ 60 psi (4.22 Kg/cm ² ) The temperature was rapidly raised to 203°C and held there for 1.5 hours. At the end of this time the product was worked up according to the procedure of Example 1. Toluene conversion was 8%. The mole percent selectivity of the product based on toluene 100 was: Phenyl acetate 56% Methylene diacetate 58% Benzyl acetate 9% Others 35% Thermal decomposition of methylene diacetate to paraformaldehyde and acetic anhydride In each reference example, the thermal decomposition of methylene diacetate to paraformaldehyde and acetic anhydride is a homogeneous gas. A phase reaction was achieved by heating at approximately 500°C. Alternatively, catalytic pyrolysis of methylene diacetate was carried out in the presence of a catalyst consisting of 5% sodium chloride mixed with silica gel that had been dried and combusted at about 300°C. n
- Methylene diacetate dissolved in hexane is passed through a tubular reactor filled with catalyst.
Passage was carried out at a temperature of 300° C. with a space velocity of 900 hr ⁻¹ . Paraformaldehyde and acetic anhydride were condensed in a downward stream and separated. Selectivity was 93% for acetic anhydride in each example for both methods.
For paraformaldehyde, it exceeds 95%. Thermal decomposition of phenyl acetate into hydroquinone or resorcinol and ketene In Reference Examples 1 to 4, the thermal decomposition of phenyl acetate into phenol and ketene was carried out at 625°C by passing it through a well-controlled tubular reactor. Achieved feverishly. The effluent from each reference case was condensed and 84
% yield of hydroquinone or resorcinol and 89%
gave a yield of ketene. Thermal decomposition was also successful when the reaction was carried out at somewhat lower temperatures at space velocities between 900 hr ^-1 and 100 hr ^-1 in the presence of triethyl phosphate catalyst. This method provided yields of both products in excess of 90% in each example. Reference Example 9 Gaseous ketene obtained from phenyl acetate pyrolysis reacts exothermically with acetic acid (distilled from the oxidation reaction product) in a scrubber reactor with sufficient heat removal capacity. The heat of reaction is 15 Kcal/mol. The reaction is carried out in two stages at 30-40°C and a pressure of 50-150 mm Hg. The conversion rates of acetic acid and ketene to acetic anhydride are 90% and 98%, respectively. Selectivity to acetic anhydride is over 95%. In the present invention, it has been found that hydroquinone or resorcinol and formaldehyde can be produced together in several steps from para-xylene or meta-xylene, respectively, in a manner similar to that of the reference examples above.
For example, para-xylene can be oxidized in known manner to paracresyl acetate, which can be further oxidized to hydroquinone diacetate according to the method of the invention. Oxidation of each methyl group liberates one mole of methylene diacetate. Hydroquinone diacetate is saponified to give hydroquinone and acetic acid. Effects of the Invention In this context, persulfate promoters enhance the oxidation of complex methyl aromatics such as p-cresyl diacetate much more dramatically than they enhance the oxidation of toluene. was found to increase the speed and selectivity of For example, para-cresyl diacetate was found to be oxidized very poorly at 200 DEG C. in the presence of a strong acid and acetic anhydride in the absence of a persulfate promoter. Baskirov (British patent 1244080)
found that to achieve the oxidation of paracresyl acetate in the presence of acetic anhydride, it was necessary to raise the reaction temperature to 230°C and the selectivity (20%) was extremely low. Using a persulfate promoter, the process of the present invention now achieves selectivity to the hydroquinone precursor of greater than 60% at temperatures not higher than 200°C and further isolates methylene diacetate as a co-product in equimolar amounts. Probably. The ability to recover methylene diacetate in equimolar quantities in all of these cases is of considerable practical value. This is because it does not lose or waste the methyl group (as ^CO2 ) and converts it into a valuable chemical product, while simultaneously producing the desired phenol precursor. The persulfate promoter described above is obtained in one form by mixing potassium persulfate with sodium bisulfate. EXAMPLES The following examples are given to illustrate but not to limit the scope of the invention described herein. The following examples are given solely for the purpose of illustrating the novel method of the present invention and are not intended to be limiting. Example 1 25 ml of para-cresyl acetate; 25 ml of benzene
ml of sulfuric acid; 0.20 g of sodium bisulfate; 0.20 g of potassium persulfate; Ta. The cylinder was rocked at 200°C for 90 minutes, cooled,
The product was released and analyzed by GLPC (Gas Liquid Partition Chromatography). Paracresyl acetate was converted (10%) to methylene diacetate (40% selectivity) and hydroquinone diacetate (63% selectivity) and other oxidation byproducts. Selectivity is based on converted para-cresyl acetate. Example 2 25 ml of para-cresyl acetate; 25 ml of benzene
ml; 0.06 g of sulfuric acid; 0.10 g of sodium bisulfate; 0.10 g of potassium persulfate; Ta. The cylinder was rocked at 200 °C for 90 min, cooled,
It was opened and the product was analyzed by GLPC. Paracresyl acetate was converted (6%) to methylene diacetate (33% selectivity) and hydroquinone diacetate (59% selectivity) and other products. Example 3 Meta-cresyl acetate was oxidized in the manner of Reference Example 1 to give methylene diacetate and resorcinol diacetate along with other oxidation by-products. Reference examples 10-12 Sulfuric acid (0.11
g); Acetic anhydride (11.4ml) and benzylidene diacetate (4g) under pressure (145psi (10.19Kg/
The following reactions were carried out in a rocking autoclave at 20% O ₂ in N ₂ cm ² ). Analysis was done by gas chromatography.

[Table] Phenyl acetate and methylene diacetate can be recovered and separated using conventional methods such as distillation.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the overall aspects of the reaction from m- or p-cresyl acetate to the final product. 1...air, 2...m- or p-cresyl acetate, 3...catalyst, 4...m- that did not react
or p-cresyl acetate, Ac ₂ O and intermediates,
5...Supplementary acetic anhydride, 6...Ac ₂ O, 8...methylene diacetate, 9...acetic acid, 10...hydroquinone or resorcinol diacetate, 11...
... Acetic acid, 12 ... Reactor, 13 ... Extraction of H ₂ SO ₄ , 14 ... Distillation, 15 ... Thermal decomposition, 16 ... Saponification, 18 ... Formaldehyde, 19 ... Hydroquinone or resorcinol.

Claims (1)

Claims: 1 (a) oxidation of paracresyl acetate with air or oxygen in the presence of a strong acid catalyst, acetic anhydride, and a persulfate promoter under elevated temperature and pressure in the liquid phase;
producing approximately equimolar amounts of hydroquinone diacetate and methylene diacetate together with acetic acid; (b) separating and recovering the hydroquinone diacetate and methylene diacetate; (c) saponifying the hydroquinone diacetate to produce hydroquinone and acetic acid. and (d) oxidizing paracresyl acetate to produce hydroquinone and formaldehyde or paraformaldehyde, which comprises thermally decomposing the methylene diacetate to recover formaldehyde or paraformaldehyde and acetic anhydride. 2. The method of claim 1, wherein the persulfate promoter is produced from a combination of potassium persulfate and sodium bisulfate. 3 (a) Oxidation of metacresyl acetate with air or oxygen to resorcinol diacetate and methylene diacetate in the presence of a strong acid catalyst, acetic anhydride, and a persulfate promoter under elevated temperature and pressure in the liquid phase. (b) separating and recovering the resorcinol diacetate and methylene diacetate; (c) saponifying the resorcinol diacetate to recover resorcinol and acetic acid; (d) A method for oxidizing metacresyl acetate to produce resorcinol and formaldehyde or paraformaldehyde, which comprises thermally decomposing methylene diacetate to recover formaldehyde or paraformaldehyde and acetic anhydride. 4. The method of claim 3, wherein the persulfate promoter is formed from a combination of potassium persulfate and sodium bisulfate.