GB1579702A

GB1579702A - Production of phenoxybenzaldehyde

Info

Publication number: GB1579702A
Application number: GB6684/77A
Authority: GB
Original assignee: Imperial Chemical Industries Ltd
Current assignee: Imperial Chemical Industries Ltd
Priority date: 1977-02-17
Filing date: 1977-02-17
Publication date: 1980-11-19
Also published as: ZA78907B; NZ186468A

Description

(54) PRODUCTION OF PHENOXYBENZALDEHYDE (71) We, IMPERIAL CHEMICAL INDUSTRIES LIMITED, Imperial Chemical House, Millbank, London SW1P 3JF a British Company, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to a process for the preparation of phenoxybenzaldehydes.

Phenoxybenzaldehydes are intermediates of use in the preparation of insecticides, including, for example, those disclosed in British patent Specifications nos. 1,243,858 and 1,413,491. The phenoxybenzaldehydes are converted to their cyanohydrins and these are then esterified by reaction with, for example, the acid chlorides of chrysanthemic acid or 3-(2,2-dichlorovinyl) -2,2-dimethylcyclopropane acid to give the insecticidal products. The acyano-3-phenoxybenzyl esters of these acids are particularly useful insecticides.

It has previously been proposed to make 3-phenoxybenzaldehyde by treating a 3-phenoxybenzyl halide, for example the chloride, with formaldehyde and ammonia, and thereafter decomposing the hexamethylenetetraminium salt thus formed by heating with, for example, acetic acid to yield the required aldehyde. This method has the disadvantage that the 3-phenoxybenzyl halide must first be obtained by halogenation of 3-phenoxytoluene, which process gives rise to a number of unwanted side-products such as the corresponding benzal halides and compounds in which the benzene rings are directly halogenated.

The process of the present invention enables phenoxybenzaldehydes to be produced by direct oxidation of the corresponding phenoxytoluene in a single step.

Accordingly the present invention provides a process for the preparation of a phenoxybenzaldehyde which comprises contacting the corresponding phenoxytoluene in the vapour phase with molecular oxygen in the presence of an oxide of a metal of Group VA, VB or VIA of the Periodic Table of Elements.

The Periodic Table referred to is that given on page 2 of the first edition of 'Modern Aspects of Inorganic Chemistry' by H J Emeleus and J S Anderson published by Routledge and Kegan Paul Ltd (London) and the metals included in the three subgroups are vanadium, niobium, tantalum, antimony, bismuth, chromium, molybdenum and tungsten.

The most favoured oxides are those of vanadiun, antimony or molybdenum which may be used alone but which are preferably used in combination with other metal oxides.

Thus vanadium oxide may be combined with one or more oxides of phosphorus, molybdenum, bismuth and tellurium; antimony oxide may be combined with one or more oxides of uranium, tin, bismuth, iron, molybdenum, tungsten, tellurium, copper, titanium and cobalt while molybdenum oxide may be combined with one or more oxides of bismuth and tin.

Various promoters may also be used in conjunction with the metal oxides disclosed above, the promoters being compounds e.g.

oxides of one or more of the following metals, cobalt, iron, nickel. magnesium and/or zinc.

The metal oxide(s) may be supported on an inert carrier e.g. alumina, silica, silicon carbide, magnesia, spinels or charcoal.

The temperature at which the oxidation is carried out suitably lies in the range 300 to 500"C, preferably 330 to 4000 C, particularly 340" to 3700C. The pressure used is generally atmospheric and although elevated or reduced pressures e.g. 0.1 to 20 atmospheres may be used there is little to be gained by so doing.

The proportion of 3-phenoxytoluene to oxygen may vary widely the main consideration being that the mixture should be outside its explosive limits. The oxygen and phenoxytoluene mixture may also be diluted by an inert gas e.g. nitrogen, steam, argon, carbon dioxide or methane. It is preferred to use nitrogen or steam as diluent e.g. the oxygen may be in the form of air with or without steam. If steam is present it is prefcrred that its proportion is up to 10 volumes per volume of the phenoxytoluene.

The metal oxide may be in the form of a fixed or fluidised bed. The gas-hourly space velocity through the bed preferably is in the range 100-30,000 litres/litre bed/hour.

The phenoxybenzaldehyde which is produced in the process may be recovered using standard tcchniqucs e.g. by condensation or absorption by solvents or porous solids.

The process according to the invention may be used for the production of 3-phenoxybenzaldehyde from 3-phenoxytoluene, 2-phenoxybenzaldehyde from 2-phenoxytoluene and 4-phenoxybenzaldehyde from 4-phenoxytoluene rcspectively.

The invention will now be further described with reference to the following examples.

EXAMPLE I A catalyst of composition 80% by weight of a material of formula Mg4.sFe4Bi2Po.sMo,205, and 20% by weight of silica was prepared by dissolving 70.6 grams ammonium molybdate tetrahydrate of formula (NH4)6Mo7024.4H2O in water with the minimum of heating, adding with stirring 1.9 gram aqucous phosphoric acid (85% by weight H1PO4) and 76.7 grams colloidal silica in water (30% SiO2 by weight). The solution was stirred for 30 minutes at room temperature when there was added 53.7 grams ferric nitrate nonahydrate dissolved in water and in turn 38.5 grams magnesium nitrate hexahydrate and 32.4 grams bismuth nitrate pcntahydrate dissolved in water containing 8 mls concentrated nitric acid (68% by weight). The rcsulting paste was heated with constant stirring until gel formation took placc. The gcl was heated at about 1300C in a stream of air in an oven and the product so obtained was finally heated for 5 hours at 320"C and then 20 hours at 550"C before being ground to size (1.03 to 0.422 mm, 16-36 BSS mesh). A mixture of 3-phenoxytoluene (1 litre of vapour per hour) and air (10 litres per hour) was passed through a bed of the above catalyst (20 grams) at a temperature of 350"C and at atmospheric pressure. The vapours leaving the catalyst bed were analysed by vapour phase chromatography, the results indicating that 3-phenoxybenzaldehyde was formed at a rate of 1 x l0 moles per hour and carbon dioxide at 4 x 10-3 moles per hour.

EXAMPLE 2 20 Mls of dried spherical alpha-alumina beads were immersed in a solution of ammonium metavanadate dissolved in dilute nitric acid. The excess liquid was removed, the beads dried in vacuo and then calcined at 350it for 16 hours. The dried catalyst contained 7% vanadium pentoxide (V2O5) by weight.

The catalyst was charged to a silica reactor tube of internal diameter 22 mms fitted with a central thermocouple well of internal diameter 7 mms. When the catalyst had been heated to 35 00C a mixture of 3-phenoxytoluene (10 grams/ hour) and air (9.6 litres/hour) was passed through the tube. The vapours leaving the tube were condensed and analysed by gas-liquid chromatography. The rate of formation of 3-phenoxybenzaldehyde was found to be 0.025 moles/litre of catalyst/hour and that of carbon dioxide 0.003 moles/litre/hour.

WHAT WE CLAIM IS: 1. A process for preparing a phenoxybenzaldehyde which comprises contacting the corresponding phenoxytoluene in the vapour phase with molecular oxygen in the presence of an oxide of a metal of group VA, VB or VIA of the Periodic Table of Elements.

2. A process as claimed in Claim 1 wherein the oxide is an oxide of vanadium, antimony or molybdenum.

3. A process as claimed in Claim 2 in which the oxide is an oxide of vanadium and it is combined with one or more oxides of phosphorus, molybdenum, bismuth and tellurium.

4. A process as claimed in Claim 2 in which the oxide is an oxide of antimony and it is combined with one or more oxides of uranium, tin, bismuth, iron, molybdenum, tungsten, tellurium, copper, titanium and cobalt.

5. A process as claimed in Claim 2 in which the oxide is an oxide of molybdenum and it is combined with one or more oxides of bismuth and tin.

6. A process as claimed in Claim 1 in which the metal oxide is used in conjunction with a promoter which is an oxide of cobalt, iron. nickel. magnesium or zinc.

7. A process as claimed in any of Claims 1 to 6 carried out within the temperature range 300 to 5000C, and at a pressure within the range 0.1 to 20 atmospheres.

8. A process as claimed in Claim 7 carried out at atmospheric pressure.

9. A process as claimed in Claim 1 wherein the molecular oxygen is used in the form of air.

10. A process as claimed in Claim 1 in which the metal oxide is in the form of a fixed or fluidised bed.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

The proportion of 3-phenoxytoluene to oxygen may vary widely the main consideration being that the mixture should be outside its explosive limits. The oxygen and phenoxytoluene mixture may also be diluted by an inert gas e.g. nitrogen, steam, argon, carbon dioxide or methane. It is preferred to use nitrogen or steam as diluent e.g. the oxygen may be in the form of air with or without steam. If steam is present it is prefcrred that its proportion is up to 10 volumes per volume of the phenoxytoluene.

The metal oxide may be in the form of a fixed or fluidised bed. The gas-hourly space velocity through the bed preferably is in the range 100-30,000 litres/litre bed/hour.

The phenoxybenzaldehyde which is produced in the process may be recovered using standard tcchniqucs e.g. by condensation or absorption by solvents or porous solids.

The process according to the invention may be used for the production of 3-phenoxybenzaldehyde from 3-phenoxytoluene, 2-phenoxybenzaldehyde from 2-phenoxytoluene and 4-phenoxybenzaldehyde from 4-phenoxytoluene rcspectively.

The invention will now be further described with reference to the following examples.

EXAMPLE I A catalyst of composition 80% by weight of a material of formula Mg4.sFe4Bi2Po.sMo,205, and 20% by weight of silica was prepared by dissolving 70.6 grams ammonium molybdate tetrahydrate of formula (NH4)6Mo7024.4H2O in water with the minimum of heating, adding with stirring 1.9 gram aqucous phosphoric acid (85% by weight H1PO4) and 76.7 grams colloidal silica in water (30% SiO2 by weight). The solution was stirred for 30 minutes at room temperature when there was added 53.7 grams ferric nitrate nonahydrate dissolved in water and in turn 38.5 grams magnesium nitrate hexahydrate and 32.4 grams bismuth nitrate pcntahydrate dissolved in water containing 8 mls concentrated nitric acid (68% by weight). The rcsulting paste was heated with constant stirring until gel formation took placc. The gcl was heated at about 1300C in a stream of air in an oven and the product so obtained was finally heated for 5 hours at 320"C and then 20 hours at 550"C before being ground to size (1.03 to 0.422 mm, 16-36 BSS mesh). A mixture of 3-phenoxytoluene (1 litre of vapour per hour) and air (10 litres per hour) was passed through a bed of the above catalyst (20 grams) at a temperature of 350"C and at atmospheric pressure. The vapours leaving the catalyst bed were analysed by vapour phase chromatography, the results indicating that 3-phenoxybenzaldehyde was formed at a rate of 1 x l0 moles per hour and carbon dioxide at 4 x 10-3 moles per hour.

EXAMPLE 2

20 Mls of dried spherical alpha-alumina beads were immersed in a solution of ammonium metavanadate dissolved in dilute nitric acid. The excess liquid was removed, the beads dried in vacuo and then calcined at 350it for 16 hours. The dried catalyst contained 7% vanadium pentoxide (V2O5) by weight.

The catalyst was charged to a silica reactor tube of internal diameter 22 mms fitted with a central thermocouple well of internal diameter 7 mms. When the catalyst had been heated to 35 00C a mixture of 3-phenoxytoluene (10 grams/ hour) and air (9.6 litres/hour) was passed through the tube. The vapours leaving the tube were condensed and analysed by gas-liquid chromatography. The rate of formation of 3-phenoxybenzaldehyde was found to be 0.025 moles/litre of catalyst/hour and that of carbon dioxide 0.003 moles/litre/hour.

WHAT WE CLAIM IS: 1. A process for preparing a phenoxybenzaldehyde which comprises contacting the corresponding phenoxytoluene in the vapour phase with molecular oxygen in the presence of an oxide of a metal of group VA, VB or VIA of the Periodic Table of Elements.
2. A process as claimed in Claim 1 wherein the oxide is an oxide of vanadium, antimony or molybdenum.
3. A process as claimed in Claim 2 in which the oxide is an oxide of vanadium and it is combined with one or more oxides of phosphorus, molybdenum, bismuth and tellurium.
4. A process as claimed in Claim 2 in which the oxide is an oxide of antimony and it is combined with one or more oxides of uranium, tin, bismuth, iron, molybdenum, tungsten, tellurium, copper, titanium and cobalt.
5. A process as claimed in Claim 2 in which the oxide is an oxide of molybdenum and it is combined with one or more oxides of bismuth and tin.
6. A process as claimed in Claim 1 in which the metal oxide is used in conjunction with a promoter which is an oxide of cobalt, iron. nickel. magnesium or zinc.
7. A process as claimed in any of Claims 1 to 6 carried out within the temperature range 300 to 5000C, and at a pressure within the range 0.1 to 20 atmospheres.
8. A process as claimed in Claim 7 carried out at atmospheric pressure.
9. A process as claimed in Claim 1 wherein the molecular oxygen is used in the form of air.
10. A process as claimed in Claim 1 in which the metal oxide is in the form of a fixed or fluidised bed.
11. A process as claimed in Claim 11 in

which the gas-hourly space velocity through the bed is in the range 100 to 30,000 litres/litre bed/hour.
12. A process as claimed in Claim 1 wherein 3-phenoxybenzaldehyde is prepared from 3-phenoxytoluene.
13. Processes as claimed in Claim 1, substantially as hereinbefore described with particular reference to Example 1 or Example 2.