CA1146966A

CA1146966A - Catalytic process for the conversion of toluene to equimolar amounts of phenol and formaldehyde

Info

Publication number: CA1146966A
Application number: CA000323630A
Authority: CA
Inventors: James E. Lyons; Robert W. Shinn; George Suld
Original assignee: Sun Tech Inc
Current assignee: Sun Tech Inc
Priority date: 1978-03-27
Filing date: 1979-03-15
Publication date: 1983-05-24
Also published as: DE2912098C2; GB2017098A; IT1113044B; JPS6445323A; GB2017098B; NL7902258A; FR2421162A1; JPS54130510A; JPH036128B2; JPS6445339A; FR2421162B1; JPH0260655B2; DE2912098A1; IT7921301A0

Abstract

ABSTRACT OF THE DISCLOSURE

Equimolar amounts of phenol and formaldehyde may be prepared from oxygen and toluene. The catalytic oxidation of toluene, when carried out in the presence of acetic anhydride, forms phenyl acetate and methylene diacetate. Pyrolysis of these two intermediates yields phenol and fomaldehyde.
Significant improvements in this process are achieved when the first stage of the reaction is carried out in the presence of MoO3.
In a further embodiment of this invention it has been found that Group VIII dithiosemibenzil compounds, part-icularly nickel dithiosemibenzil, serves as a superior pro-moter for the toluene oxidation reaction.
In still a further embodiment of this invention it ? found: ????
pr?f?, ? c-d, c ????
cularly effective promoters for the ?luen? x? ??
In a like manner, hydroquinone ? ? may be obtained from cresyl acetates.
In a furhter embodiment of this invention is has been found that benzylidene acetate may be converted to phenyl acetate and methylene diacetate by acid-catalyzed reaction in the presence of oxygen and acetic anhydride.

Description

Significantly, there is no mention or suggestion of the formation of methylene diacetate, and therefore obviously no teaching of converting said methylene diacetate to form-aldehyde. Moreover, the Russian work is silent as to the use of any promoters or other adjuvants in addition to acid catalysts which would serve to enhance the rate, yield, or selectivity of this oxidation reaction.

- Summary of the Invention In accordance with the present invention there is provid~d a novel process for the oxidation of toluene to ultimately yield equimolar amounts of phenol and formaldehyde or paraformaldehyde. In general, this is achieved by oxidiz-ing toluene with air or oxygen at selected pressures and temperatures in the liquid phase in the presence of acetic anhydride and a strong acid cataly~t to form phenyl acetate and methylene diacetate in equal amounts together with acetic acid. The methylene diacetate and phenyl acetate are separated hy distillation of the reaction product. The phenyl acetate is then pyrolyzed to form phenol and ketene, while the methylene diacetate is pyrolyzed tc form formaldehyde and acetic anhydride. The acetic acid and ketene may then be con-verted to acetic anhydride by known methods and recycled to the oxidation step.

The oxidation step is further characterized, in accordance with this invention, by the use of molybdenum trioxide for purposes of suppressing the formation of un-wanted CO2, or by the use of Group VII~ dithiosemibenzil com-pounds or persulfates as promoters for the oxidation reaction.
Op-tionally, these additives may be employed simultaneously.

Finally this process is also characterized by the use of certain select temperatures and pressures which further enhance the yi.eld of the desired products~

Desc~ription_of the Drawing Figure 1 is a block flow diagram which shows each aspect of the overall reaction from toluene to final products~

~escri~tion of the React on As aforementioned, the ~irst step o~ this process is the liquid phase oxidation of toluene using a strong acid catalyst to form phenyl acetate and methylene diacetate.
This reaction may be illustrated as follows:

PhC~3 + 2 ~ 2Ac2O 2~ 4 ~ PhOAc + CH2(OAc~2 + HOAc wherein the weight ratio of toluene to acetic anhydride is in the range of from about 50:1 to 1:10~ and preferably 10:1 to

2:1, while the ratio o~ H2SO4 to toluene employed is from about 5 x 10 4 to 1 x 10 2, and preferably 1 x 10 3 to 5 x 10 3.

The reaction, which employs oxygen or equivalent amounts of air, should be carried out at temperatures in the range of from about 140 to 300C, and preferably about 150 to 250C, and at initial pressures of from about 50 to 450 psig. The pressure is desirably generated by charging to an autoclave air or mixtures of oxygen and nitrogen having an oxygen/nitrogen ratio of from 10:1 to 1020 psig. The reaction mixture is then heated and the reactor pressure rises accord-ingly.

The reaction may be run in ex~ess toluene as a ' : -4-.. . . -~6~166 solvent or in organic solvents such as benzene, chlorobenzene, or acetic acid. Carrying out the reaction in inert solvents such as benzene or chlorobenzene does not appreciably affect yield or selectivity but when acetic acid is employed, sig-nificantly increased selectivities may be observed. In order for rapid reactions in acetic acid, promoters such as Caro's dry acid should be employed.

It has been discovered that for purposes of pro-viding a smoothly catlayzed reaction without the forma-tion of considerable quantities of unwanted CO~ by-product, there should desirably be employed in the course of this reaction MoO3. This oxide is preferably added in amounts of 19 3 to 10 2g per gram of toluene~

In a urther embodiment of this inventian it has also been found that when a Group VIII dithiosemibenzil complex, such as nickel dithiosemibenzil is added to the reaction it serves as a promoter for the oxidation, thereby increasing the extent of reaction. This promoter is desirably used in amounts of from about 10 3 to 10 ~g per gram of toluene.

If desired, both the MoO3 catalyst and the promoters may be used jointly, although this is not essential. However, enhanced results are generally obtained thexeby.

The reaction product containing phenyl acetate and methylene diacetate, as well as lesser amounts of such pro ducts as benzyl acetate and benzylidene diacetate is then routinely treated to remove the acid catalyst therefrom. The phenyl acetate and methylens diacetate are then separated by distillation under vacuum.

The recovered phenyl acetate is then converted to phenol and ketene by pyrolysis. This is conventionally achieved by heating the phenyl acetate at temperatures oE
from about 500 to 1000C, preferably at about 625C, pre-ferably in the presence o a catalyst such as triethylphos~
phate, and separating the effluent phenol and ketene by con-ventional means.

In a like manner, the pyrolysis of methylene diacetate yields formaldehyde and acetic anhydrideO This pyxo-lysis is conventionally carried out in one step in a homo-geneous gas phase reaction, at about 450-550C under reduced pressure. The ketene recovered from the phenyl acetate pyro-lysis, together with the acetic acid reco~ered from the oxida-tion of the toluene, may then be converted to acetic anhydride for recycling tQ the initial oxidation step. This is readily achieved by contacting the gaseous ketene with acetic acid at room temperature in the liquid phase.

I~ has been discovered that one of the by-products of the toluene o~idation, benzylidene diacetate, can be con-verted to phenyL acetate and methylene diacetate and there-fore may be recycled to enhance overall product yields. This reaction is novel and proceeds by a route which does not have precedent in the literature.

The reaction of benzylidene diacetate to give methylene diacetate and phenyl acetate may be carried out under elevated temperatures of ~rom about 150 to 250C, pre-ferably 200 to 220C~ and initial pressures at room temperature, ~6~

of from about lO0 to 300 psig, of an O2 containing gas~ pre-ferably l90 to ~20 psig, in an augoclave for period~ ranging from about 15 minutes to 4 hours, depending upon the pressures and temperatures employed.

The benzylidene diacetate, (5~25 wt.~) should desirably be reacted in a solv~nt such as benzene. The acetic anhydride should desirably be present in amounts of 2-3 times by weight of the amount of banzylidene diacetate used. The amount of acid catalyst employed should be in con-centrations ranging from about 10 1 to lO 2, preferably 2 x 10 2 to 4 x 13 2, moles/liter.

Air may be used in place of O~, in which case the amounts are increased proportionatly to provide an equivalent amount of O~.

The acid catalyst is desirably suluric acid, but other like acids such as peroxymonosulfuric acid, Caro's dry reagent, or mixtures thereof, may be used instead.

If desired, small amounts of initiators such as azobisi~obutyronitrile, dibenzoylperoxide and the like may be added to help initiate the reaction. Generally, 0.2 wt.%, is suficient for this purpose.

The following examples are provided to illustrate, but not to limit, the scope of the invention described here-ir~.

~7--The following examples are provided solely forpurposes of illustrating but not limiting the novel process of this invention.

The following ingredients were charged to a 300 ml rocking autoclave reactor:

toluene240 m mole acetic anhydride120 m mole H2S0~ l m mole N2 230 psi 2 6a psi The temperature was rapidly raised to 203C where 'it was maintained for one hour. At the end of this time rapid cooling was accomplished first by air, then by cold water immersion. This was followed by analysis of both the gas and liquid phases. Mass spectrometric analysis of the gas phase together with measurement of pressure decrease showed that the ratio of moles of C02 produced to moles of 2 consumed was 0.21.

Standardized gas chromatographic analysis of the liquid phase showed that toluene conversion was 9%, and ~60%
of the acetic anhydride had been consumed.

: Product selectivities (%) based on toleune conver-ted were:

Phenyl acetate 52 Methylene diacetate 52 o-methyl phenyl acetate 4 oenzyl acetate 16 phenoxymethylene acetate 6 benzylidene diacetate 6 tars and others 16 The following ingredients were charged to a 300 ml roc~ing .
:

. .

autoclave reactor:

toluene240 m mole acetic anhydride120 m mole H~S04 1 m mole MoO3 0.1 g N2 230 psi 2 60 psi The tempexature was rapidly raised to 201C where it was maintained for one hour. At the end of this tlme~
the product was worked up in accordance with the procedures of Example 1. The ratio of moles of C02 produced to moles of 2 consumed was 0.08.

.

Standardi~ed gas chromatographic analysis of the liquid phase showed that toleune conversion was 10%.

Product selectivities (%) based on toleune converted were:

phenyl acetate 54methylene diacetate 54 o-methyl phenyl acetate 4 benzyl acetate 15 pheno~ymethylene acetate 6 benzylidene diacetate 6 tars and othexs 15 10~

: EX~PLE 3 ~ The following ingredients were:charged to a 300 ml rocking autoclave reactor:

toluene 240 m mole acetic anhydride120 m mole H2S0~ 1 m mole : MoO3 0.1 g Ni dithiosem.ibenzil 0.15 m mole N2 : 230 psi 2 60 psi : 9 ~. , The temperature was rapidly raised to 203C where it was maintained for one hour. At the end of this time, the product was worked up in accordance with the procedures of Example 1. The ratio of moles of CO2 produced to the moles of 2 consumed was 0.10.

Standardized gas chromatographic analysis of the liquid phase showed that toluene conv~rsion was 16%.

Product selectivities (~) based on toluene con-verted were:

phenyl acetate 50methylene diacetate 51 o-methyl phenyl acetate 4 benzyl acetate 18 phenoxymethylene acetate 8 benzylidene diacetate6 tars and ot~ers 14 A comparison of the CO2/O~ ratio of Example 1 with that of Examples 2 and 3 clearly demonstrates the effective-ness of MoO3 in suppressing CO2 formation.

The following ingredients were charged to a 300 ml rocking autoclave reactor:

toluene 240 m mole acetic anhydride 120 m mole H2SO4 1 m mole CrO3 0.1 g N2 230 psi 2 60 psi The temperature was rapidly raised to 202C where it was maintained for one hour. At the end of this time, the product was worked up in accordance with the procedures of Example 1. The ratio of moles of CO2 produced to the moles ' 10 6~

of 2 consumed was ~0.3.

Standardized gas chromatographic analysis of the liquid phase showed that toluene conversion was 11%.

Product selectivities (~) based on toluene converted were:

phenyl acetate 20methylene diacetate 19 o-methyl phenyl acetate 5 benzyl acetate 36 phenox~nethylene acetate 12 benzylidene diacetate 16 tars and others 11 ~ .

The following ingredients were charged to a 300 ml rocking autoclave reactor:

toluene 240 m mole acetic anhydride 1~0 m mole H2SO4 1 m mole ~3 0~1 N2 230 psi 2 60 psi The temperature was rapidly raised to 203C where it was maintained for one hour. At the end of this time the product was worked up in accordance with the procedures of Example 1. The ratio of moles of CO2 produced to the moles of 2 consumed was 0.25.

Standardized gas chromati.graphic analysis of the liquid phase showed that toluene conversion was 8%.

Product selectivities (%) based on toluene converted were:

phenyl acetate' 35 methylene diacetate 50 o-me~hyl phenyl acetate 2 benzyl acetate 35 phenoxymethylene acetate 3 benxyldene diacetate 4 tars and others 21 A comparison of the selectivities of Examples 2 and 3, where MoO3 was employed, with the results obtained ~rom CrO3 and WO3 in Examples 4 and 5, will reveal that MoO3 is far superior to these other metals for purpos~s of obtain-ing the desired phenyl acetate and methylene diacetate. In addition the MoO3 provided a smoothly catalyzed reaction with little burn to CO2 whereas in the cases of CrO3 and WO
2.5 to 4~0 times as much CO~ was produced.

The ollowing ingredients were chaxged to a 300 ml rocking autoclave reactor:

toluene240 m mole acetic anhydride120 m mole H2SO4 1 m mole K2S28 Ool g N2 230 psi 2 60 psi The temperature was rapidly raised to 201C where it was maintained for one hour. At the end of this time, the product was worked up in accordance with the procedures of Example 1.

Standardized gas chromatographic analysis of the liquid phase showed that toluene conversion was 16%.

Product selectivities (%) based on toluene converted were:

, . -.

phenyl acetate54 methylene diacetate 51 o-methyl phenyl acetate4 benzyl acetate 15 phenoxymethylene acetate 6 benzylidene diacetate 6 tars and others 15 EXAMPLE_7 The following ingredients were charged to a 300 ml rocking autoclave reactor:

toluene240 m mole acetic anhydride 120 m mole H2SO41 m mole Dry Caro's acid0.5 g N2 230 psi 2 60 p5i .

The temperature ~as rapidly raised to 203C wher~
it was maintained fox one hour. At the end o this time, the product was worked up in accordance with the procedures o~
Example 1.

Standardized gas chromotographic analysls of the liquid phase showed that toluene conversion was 18~.

Product selectivities (%) based on toluene converted were:

phenyl acetate55 methylene diacetate 54 o-methyl phenyl acetate4 benzyl acetate 13 phenoxymethylene acetate 6 benxylidene diacetate 6 tars and others 16 ob ~XAMPLE 8 The following ingredients were charged to a 300 ml rocking autocla~e reactor: -, toluene160 m mole acetic acid80 m mole acetic anhydride 120-m mole Dry Caro's Acid0.5 g N2 230 psi 2 60 psi The temperature was rapidly ralsed to 203C where it was maintained for 1.5 hours. At the end of this ~ime the product was worked up in accordance with the procedures of Example 1. Toluene convexsion was 8%. Proauct selectivities % based on toluene were:

phenyl acetate 56%
methylene diacetate 58%
benzyl acetate 9~
others 35%
EX~MPLE 9 Pyrolysis of methylene diacetate to paraformalde-hyde and acetic anhydride is accomplished thermally at about 500C in a known manner.

Alternatively, the catalytic pyrolysis of methylene diacetate is carried out at about 300C in the presence of a catalyst composed o~ 5% sodium chloride ~ixed with silica gel dried and calcined. The methylene diacetate, dissolved in n-hexane, is passed through a passified tubular reactor packed with the catalyst at a space velocity of 900 hr 1 a.nd a temperature of 300C. Paraformaldehyde and acetic anhydride condense downstream and are separated routinely. Selectivi-ties exceed 93% for acetic anhydxide and 95% for methylene diacetate.

Pyrolysis o~ phenyl acetate ~o phenol and ketene is .

~ ~ -lg-.. . ,. , ~ . .
.

accomplished thermally at 625C by passing it through a well-conditioned tubular reactor. The effluent is condensed to give 84~ yield of phenol and 89~ yield of ketene.

The reaction may be carrled ou~ at a somewhat lower temperature in the presence of triethyl phosphate catalyst at space velocities of between 900 and 1000 hr 1. Yields in excess of 90% are ohtained.

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. ~eat of reaction is 15 kcal/mole. The reaction is carried out in two stag~s at

3~-40~C and pressures of 50-150 mm Hg. Conversions of acetic acid and ketene to acetic anhydride are 90% and 98% respect-ively. Selectivlty to acetic anhydride exceeds 95%.

In a urther embodiment of this invention lt has been found that in a manner similar ~o the above-described process, hydroquinone or resorcinol, and formaldehyde can be co-produced in several steps from p-xylene or m-xylene respectively. For example, p-xylene can be oxidized to p-cresyl acetate in a known manner which can be oxidized further to hydroquinone diacetate in accordance with the process of this invention. The oxidation of each methyl qroup liberates one molecule of methylene diacetate. Hydro~uinone diacetate can be saponified to give hydroquinone and acetic acid.

In this context, it has been found that persulfate promoters enhance the rate and selectivity of oxidation of more complex methyl aromatics such as p-cresyl a~eta~e far more dramatically than they enhance toluene oxidation. For example, it has been found that p-cresyl acetate is oxidized very poorly at 200C in the presence of strong acid and acetic anhydride in the absence o~ persulfate promoters.
Bashkirov (British Patent 1,244,080) found that it was necessary to elevate the reaction temperature to 230C to ; achieve oxidation of p-cresyl acetate in the presence of acetic anhydride and selectivity (20%) was very low. The instant process now achiPves selectivities to hydroquinone precursors of greater than 60% at temperatures no higher than 200C using persulfate promoters, and in addition will isolate methylene diacetate as a co-product in equimolar amounts. The ability to recover methylene diacetate in equimolar amounts in all of these cases is of considerable practical value since one does not lose or waste ~he methyl group (as CO2) but converts it to a valuable chemical product while at the same time producinq the desired phenolic precursor.

The aforementioned persulfate promoter, in one form, can be obtained by admixing potassium persulfate with sodium bisulfate.

Para-cresyl acetate, 25 ml, benzene, 25 ml, sulfuric acid, 0.12 gram, sodium bisulfate, 0.20 gram, potassium persulfate, 0.20 gram and acetic anhydride, 6.0 ml, were charged to a rocking autoclave and then 290 pounds of a 20/80 oxygen/nitrogen mixture was admitted. The bomb was rocked ., ' ' ~ ~ ~ 6~

for 90 minutes at 200~C, cooled, opened and the products analyzed by glpc. P _ -cresyl acetate was converted 110%) to methylene diacetate (40~ selectivity) hydro~uinone diacetate (63~ selectivity) and other by-products of oxidation. Select-ivities were based on p-cresyl acetate converted.

Para-cresyl acetate, 25 ml, benzene, 25 ml, sulfuric acid, 0.06 gram, sodium bisulfate, 0.10 gram, potassium persulfate, 0.10 gram and acetic anhydride 6.0 ml were charged to a rocking autoclave and then 290 pounds of a 20/80 oxygen~nitrogen mixture was admitted. The bomb was rocked or 90 minutes at 200C, cooled, opened and the products analyzed by glpc. Para-cresyl acetate was con~erted (6%) to methylene diacetate (33~ selectivity), hydroquinone diacetate ~59% selectivity) and other products~

~XP~PL~ 14 Meta-cresyl acetate was oxidized in the manner of Example 1 to give methylene diacetate and resorcinol diacetate together with other by-products of oxidation.

The ~ollowing reactions were run in a rocking auto-clave under pressure (145 psi of 20% 2 in N2) using sulfuric acid (0.11 gms) as the catalyst, acetic anhydride (11.4 ml) amd benzylidene diacetate (4 gms) in benzene (50 ml) for the time indicated at the temperature shown in the table.
The analyses were carried out by gas chromatography.

.

.

6~

TaB~E I
% CH2(OAc)2 % PhOAc In In Reaction Reaction Conversion Reaction Reaction Example Time,Ers~ Temp.,C of PHC~(OAc)~ Mixture Mixture 0.5 200 99 21~ 25%
16 1~0 200 99 22% ~3%
17 1.0 170 78 ~% ~%
The phenyl acetate and methylene diacetate may be recovered and separated by routine methods, as for example by distillation.

:~ -18_ .

Claims

THE INVENTION CLAIMED IS:

1. A process for the oxidation of toluene to form phenol and formaldehyde or paraformaldehyde which comprises:

(a) oxidizing toluene with air or oxygen in the liquid phase under elevated temperatures and pressures in the presence of a strong acid catalyst, acetic anhydride, and molybdenum trioxide to form phenyl acetate and methylene diacetate in approximately equimolar amounts, together with acetic acid;

(b) separating and recovering said phenyl acetate and methylene diacetate;

(c) pyrolyzing said phenyl acetate to recover phenol and ketene; and (d) pyrolyzing said methylene diacetate to recover formaldehyde or paraformaldehyde and acetic anhydride.

2. The process of Claim 1 wherein the acetic acid and ketene are converted to acetic anhydride and recycled to the oxidation step.

3. A process for the oxidation of toluene to form phenol and formaldehyde or paraformaldehyde which comprises:

(a) oxidizing toluene with air or oxygen in the liquid phase under elevated temperatures and pressures in the presence of a strong acid catalyst, acetic anhydride, and a Group VIII metal dithiosemibenzil compound to form phenyl acetate and methylene diacetate in approximately equimolar amounts, together with acetic acid;

(b) separating and recovering said phenyl acetate and methylene diacetate;

(c) pyrolyzing said phenyl acetate to recover phenol and ketene; and (d) pyrolyzing said methylene diacetate to recover formaldehyde or paraformaldehyde and acetic anhydride.

4. The process of Claim 3 wherein the acetic acid and ketene are converted to acetic anhydride and recycled to the oxidation step.

5. The process of Claim 3 wherein the Group VIII
metal dithiosemibenzil is nickel dithiosemibenzil.

6. A process for the oxidation of toluene to form phenol and formaldehyde or paraformaldehyde which comprises:

(a) oxidizing toluene with air or oxygen in the liquid phase under elevated temperatures and pressures in the presence of a strong acid catalyst, acetic anhydride, molyb-denum trioxide, and a Group VIII metal dithiosemibenzil compound to form phenyl acetate and methylene diacetate in approximately equimolar amounts, together with acetic acid;

(b) separating and recovering said phenyl acetate and methylene diacetate;

(c) pyrolyzing said phenyl acetate to recover phenol and ketene; and (d) pyrolyzing said methylene diacetate to recovex formaldehyde or paraformaldehyde.and acetic anhydride.

7. The process of Claim 6 wherein the acetic acid and ketene are converted to acetic anhydride and recycled to the oxidation step.

8. The process of Claim 6 wherein the dithio-semibenzil compound is nickel dithiosemibenzil.

9. A process for the oxidation of toluene to form equimolar amounts of phenol and formaldehyde or paraformalde-hyde which comprises:

(a) oxidizing toluene with air or oxygen in the liquid phase under elevated temperatures and pressures in the presence of a strong acid catalyst, acetic anhydride and a persulfate selected from the group consisting of sodium persulfate, potassium persulfate, persulfuric acid and Caro's dry acid to form phenyl acetate and methylene diacetate in approximately equimolar amounts, together with acetic acid;

(b) separating and recovering said phenyl acetate and methylene diacetate;

(c) pyrolyzing said phenyl acetate to recover phenol and ketene; and (d) pyrolyzing said methylene diacetate to recover formaldehyde or paraformaldehyde and acetic anhydride.

10. The process of Claim 9 wherein the acetic acid and ketene are converted to acetic anhydride and recycled to the oxidation step.

11. A process for the oxidation to toluene to form phenol and formaldehyde or paraformaldehyde which comprises:

(a) oxidizing toluene with air or oxygen in the liquid phase under elevated temperatures and pressures in the presence of a strong acid catalyst, acetic anhydride, molyb-denum trioxide and a persulfate selected from the group consisting of sodium persulfate, potassium persulfate, per-sulfuric acid, and Caro's dry acid to form phenyl acetate and methylene diacetate in approximately-equimolar amounts, together with acetic acid;

(b) separating and recovering said phenyl acetate and methylene diacetate;

(c) pyrolyzing said phenyl acetate to recover phenol and ketene; and (d) pyrolyzing said phenyl acetate to recover formaldehyde or paraformaldehyde and acetic anhydride.

12. The process of Claim 11 wherein the acetic acid and ketene are converted to acetic anhydride and recycled to the oxidation step.

13. A process for the oxidation of toluene to form phenol and formaldehyde or paraformaldehyde which comprises:
(a) oxidizing toluene with air or oxygen in the liquid phase under elevated temperatures and pressures in the presence of a strong acid catalyst, acetic anhydride and a material selected from the group consisting of:
1) molybdenum trioxide;
2) a Group VIII metal dithiosemibenzil compound, 3) molybdenum trioxide and a Group VIII metal dithiosemibenzil compound, 4) a persulfate selected from sodium persulfate, potassium persulfate, persulfuric acid and Caro's dry acid, and 5) molybdenum trioxide and a persulfate selected from sodium persulfate, potassium persulfate, persulfuric acid and Caro's dry acid, to form phenyl acetate and methylene diacetate in approximately equimolar amounts, together with acetic acid; separating and recovering said phenyl acetate and methylene diacetate;
pyrolyzing said phenyl acetate to recover phenol and ketene;
and pyrolyzing said methylene diacetate to recover formaldehyde or paraformaldehyde and acetic anhydride.

14. The process of claim 1, 3 or 6 wherein benzylidene diacetate is reacted with air or oxygen at elevated temperatures and pressures in the presence of acetic anhydride and an acid catalyst to produce phenyl acetate and methylene diacetate.

15. The process of claim 9, 11 or 13 wherein benzylidene diacetate is reacted with air or oxygen at elevated temperatures and pressures in the presence of acetic anhydride and an acid catalyst to produce phenyl acetate and methylene diacetate.