DE1768854A1 - Process for the production of organic hydroperoxides - Google Patents

Description

ATLANTIC RICHi ¹ ISLD COMPANY, Philadelphia, Pa / USA

Process for the production of organic hydroperoxides

The invention also relates to a method of manufacture of organic hydroperoxides by oxidation of compounds that have one to a tertiary carbon atom Have bonded hydrogen atom using a free oxygen-containing one Gas that delivers an Oxydationsgeiuisch, which for Epoxidation of olefinic compounds in the presence of molybdenum-containing catalysts is suitable. In U.S. Patent 2,403,771, a

109882/1915

Process for the oxidation of a tert. Carbon atom organic containing aliphatic character Compounds with the formula

RGH
t

described, in which R identical or different alkyl, aryl, aralkyl, alkaryl, al acyclic or mean heterocyclic groups on one or more of the carbon atoms of the radicals mentioned can be substituted by one or more halogen, nitrogen or other oxygen atoms. A preferred one Group of these compounds are the saturated aliphatic hydrocarbons with at least a tert. Carbon atom. The reaction is carried out with a gas containing free oxygen either in carried out in the liquid or in the gas phase in the presence of a hydrogen halide, the corresponding n Hydroperoxides are obtained in which the hydroperoxide group on a tert. Carbon atom arranged is.

In the US patent specification 2 548 43χ the oxidation of alkyl-substituted aromatic compounds with

- 3 -109882/1915

the formula

R ₁

Ar-CH
R ₂

described, in which R ₁ and R _{2 are} alkyl groups and an Ar is an aryl or alkaryl group .. The oxidation is carried out in the liquid phase and in the presence of water using a free oxygen-containing gas. It can also be seen from the cited patent that the absence of a catalyst promotes the formation of hydroperoxide.

The subject of US Patent 2,845,461 is a process for the non-catalytic oxidation of isobutane in the liquid phase to produce a mixture of tert. Butyl hydroperoxide and tert. Butyl alcohol _o The reaction takes place in the liquid phase in a reaction mixture free of metal ions with a gas containing free oxygen such as molecular oxygen at reaction temperatures between approx. 100 ° G and 150 ° C

2 and at pressures above 28 kg / cm. From the cited patent it can be seen that the presence of metal ions reduce the conversion and the yield leads. So goes z. B. from

109882/191 5

8AD

Example IV of the cited patent shows that "in a reactor contaminated with cobalt ions the Oxidation of isobutane with less conversion and with lower yields of tert. Butyl hydroperoxide going on. After cleaning the Reaktdrs with nitric acid and washing the reactor surface with water and subsequent rinsing with a 2% sodium pyrophosphate solution was able to achieve an increased conversion and higher selectivity for the Formation of the tert. Butyl hydroperoxide can be found. This improvement can be brought about by the washing treatment the removal of the source of the contaminating metal ions. In the Belgian patent 674 076 is a method for the oxidation of olefinic compounds in the presence a molybdenum-containing catalyst and using an organic hydroperoxide which is prepared by the method mentioned in the above-mentioned patent specification, as an oxidizing agent described.

According to the present invention are controlled and critical amounts of an alkali metal pyrophosphate

PlLiU

like sodium phosphate in a liquid phase, non-catalytic oxidation process

- s _ 109882/191 5

brought, "in which the compound to be oxidized has a hydrogen atom bonded to a tertiary carbon atom having an aliphatic character and in which a gas containing free oxygen is used as the oxidizing agent in order to increase the selectivity to improve the process for the production of the hydroperoxide and to produce an oxidation mixture, which acts as a source of an oxidizing agent based on an organic hydroperoxide a molybdenum catalyzed olefin epoxidation process suitable is.

The method of the invention is particularly useful for oxidation of organic compounds applicable, which one to a tertiary carbon atom with aliphatic Have character arranged hydrogen atom and which by the formula

R-C-H

it can be stated which R is the same or different Alkyl, aryl, aralkyl, alkaryl, alicyclic or heterocyclic groups are attached to a

BAl) 109882/1915

or more of the carbon atoms mentioned Radicals can be substituted by one or more halogen, nitrogen or oxygen atoms can, the total number of carbon atoms being at most 40. Particularly preferred compounds are isobutane and cumene.

According to the present invention, the oxidation reaction is a non-catalytic oxidation in the liquid phase which takes place using a gas containing free oxygen, such as air or molecular oxygen, the known reaction conditions being used. According to the United States Patent 2548 435 cumene, for example, at a temperature between 20 ° C and are preferably oxidized at 60 ° C to 80 ⁰ C 95 ° G. The main prerequisite for the compounds oxidizable by the process described in the cited patent specification is the presence of a tertiary carbon atom which is substituted with a hydrogen atom.

In the non-catalytic oxidation of isobutane with molecular oxygen in the liquid phase

- 7 -109882/191 5

get two main products, one of which is tert. Butyl hydroperoxide and the other tert. Represents butyl alcohol. The tert. Butyl hydroperoxide is special as an oxidizing agent in molybdenum-catalyzed olefin epoxidation, as cited in US Pat Belgian patent, it is generally preferred to use epoxidation in to carry out a solvent such as alcohol, the Hert formed during the oxidation of isobutane. Butyl alcohol is also used as a solvent in the epoxidation reaction can serve. Thus, for use in epoxidation, the entire oxidation mixture is as Combined solvent and oxidizing agent can be used.

The isobutane is preferably oxidized at a temperature of approx. 93 ° C to approx. 14-9 ° G, the particularly preferred temperature range being between approx. 132 ° C and approx. 14-6 ° G. Of the

Pressure is 21 kg / cm or more and is for example

p ρ

wise in the range of approx. 28 kg / cm to 4-9 kg / cm,

p ρ

with a range from about 28 kg / cm to 38.5 kg / cm something is preferred. It is also preferable to carry out the reaction in the absence of a catalyst. It has been shown that when carrying out

- 8 -109882/1915

the reaction at temperatures of about 155 G to 146 ° G and at pressures of about 28 kg / cm to 55 kg / cnr as a percentage of the tert. Butyl hydroperoxide expressed in the product - for hydroperoxide formation in the range of about 40 % to 60% by weight.

Since one of the main purposes of the oxidation mixture, ■ which in the non-catalytic oxidation reaction according to the invention is produced in the liquid phase, in use as an oxidizing agent in olefin epoxidation it is desirable to have the hydroperoxide selectivity in the oxidation, i.e. H. the hydroper to bring oxide formation to a maximum value.

In a preferred embodiment of the invention, in which the oxidation product of isobutane is used in an epoxidation, is the preferred one Epoxidation reaction represents an olefin epoxidation in which with an olefin having 2 to 50 carbon atoms is being worked on. A particularly preferred olefin is propylene. The epoxidation of propylene is in the presence of a molybdenum-containing catalyst at temperatures which are preferably between about 121.degree up to 149 ° C and at pressures of 35 kg / cm * "to

BATH

109882/1915

_ ₉ _

56 kg / cm, although you can also work at higher or lower lump doors or pressures. In propylene epoxidation, a molybdenum concentration of 50 ppm to 150 ppm, based on the total amount of the reactants, is suitable -1 is obtained «, In this sliding application a process for the production of a molybdenum-containing catalyst is described, in which molybdenum metal is reacted at a temperature of 60 ° C. or more with the bottom fraction obtained in the propylene epoxidation. Here, the bottom fraction falls in the distillation of the propylene epoxidation mixture, which is used to remove the unreacted propylene, the propylene oxide and at least part of the by-product by the reduction of the tert. Butylhydroperoxide formed tert. Butyl alcohol takes place on _o The bottom fraction contains in addition to unreacted tert · butyl hydroperoxide, tert. Butyl alcohol, water and acidic compounds also small amounts of other impurities and approx. 12 to 20% higher molecular weight polyhydroxy compounds. After conversion

- 1o 109882/1915

- 1ο -

of the molybdenum metal with this samp fraction from the epoxidation reaction becomes the whole, the soluble one Reaction mixture containing molybdenum reaction product returned to the epoxidation reaction to get into it the desired concentration of the molybdenum catalyst to maintain.

It has now been found that when an alkali metal pyrophosphate is injected into the oxidation reaction mixture in the form of a one-time addition in such an amount that the alkali metal content (this content represents a "convenient method of determining the amount of alkali metal pyrophosphate in the mixture) of the liquid reaction mixture in the range from 40 ppm to 50 ppm or more, an increase in the selectivity for the hydroperoxide formation is associated to 4%, ie at least 3 to 4 % more tert-butyl hydroperoxide, based on the weight of the product mixture, is formed

- τι -109882/1915

Oxidation reaction adds "in the subsequent Use of the oxidation mixture with the Alkalimet allpyrophosphate content "at the stage of olefin epoxidation there is a "considerable reduction in the conversion and the yield of the Bpoxide. This applies especially when propylene is epoxidized.

According to the present invention, an oxidation mixture in which the oxidation is carried out by a free oxygen containing gas is carried out, a sufficient amount of alkali metal pyrophosphate is added that an increase in hydroperoxide selectivity is obtained. In general, amounts as low as 0.1 ppm alkali metal are used from the alkali metal pyrophosphate sufficient, wherein the amount can be up to 100 japm or more. In a preferred embodiment, the alkali metal pyrophosphate injected into the reaction mixture either in small individual amounts or continuously, in amounts that are sufficient in the oxidizing pn Product stream to give an alkali metal content of 0.1 to 10 ppm.

According to a particularly preferred embodiment Sodium pyrophosphate in the isotutane oxidation reaction

109882/1915 - 12 -

Mix either continuously or in small individual quantities injected in such a way that the sodium content in the product mixture stream does not exceed 10 ppm increases, and that the concentration is preferably between 1 and 3 ppm is maintained. Under these conditions there will be the same 3 to 4% improvement in tert. Butyl hydroperoxide selectivity obtained, but there is no significant reduction in propylene epoxidation when the oxidation mixture is used the conversion or the yield of propylene epoxidation instead.

The alkali metal pyrophosphate is conveniently in the form an aqueous solution introduced into the oxidation reaction, but the concentration of this solution is not critical. A suitable concentration is, for example, 2% by weight. However, you can also use higher or lower concentrations work, for example be in the range of 0.1 wt% to 5 wt%. Potassium pyrophosphate, which is more soluble than the sodium compound can be in the form of solutions up to 25% by weight can be used. Although due to its easier accessibility sodium pyrophosphate is preferred, the other alkali metal pyrophosphates, such as the lithium and potassium compounds, are equally suitable.

109882/1915 BAD

In the following, the invention will be based on a few examples are explained in more detail:

Example I:

A 24 liter stainless steel oxidation vessel with a Inside diameter of 15 »24 cm was made with isobutane and charged with molecular oxygen. The isobutane was at a rate of 2,000 ml per hour, the oxygen was added at a rate of 170 l / h. At a temperature of 135 ° G and

2-9.4- kg / cm contained the reaction product stream 51 wt% tert. Butyl hydroperoxide, the conversion of isobutane being 44%. Under these reaction conditions, 250 ml of a 2% strength by weight aqueous solution of sodium pyrophosphate decahydrate Na ^ PoOr ₇ -IO H2O were injected all at once into the reactor. This increased the selectivity, ie the tert. Butyl hydroperoxide content of the oxidation product increased to 55% by weight without any significant change in the conversion.

Example II:

In a further experiment, the reactor of Example I with 3 100 ml / h isobutane and 200 l / h molecular

- 14 -109882/1915

Oxygen charged. At 146 ° C and 32.2 kg / cm ^ was the tert. Butyl hydroperoxide selectivity 39% by weight, the isobutane conversion being 53%. Under these reaction conditions, 100 ml of the sodium pyrophosphate decahydrate solution were all at once into the reactor of example I injected. The tert. Butyl hydroperoxide e ectivity increased to 4-3 wt%, there was no significant change in the conversion ο

Example III:

In a third experiment, the reactor was charged with 3,200 ml / h of isobutane and 280 l / h of molecular oxygen. At 143 ° G and a pressure of about 33 »6 kg / cm, the tert. Butyl hydroperoxide selectivity 41% with an isobutane conversion of 48 % . When the plant was operated under these conditions, a continuous metering in of 1.7 ml / h of the pyrophosphate solution used in Examples I and II was initiated. The tert. The electivity of butyl hydroperoxide increased from 41 to 44% by weight without any appreciable change in the conversion taking place.

- 15 109882/1915

These examples show that by injecting less than 10 ppm (measured as the alkali metal concentration of the alkali metal pyrophosphate) in the reaction mixture a considerable increase in the hydroperoxide selectivity can be obtained, either by a one-time large addition or by a continuous feeding.

In each of the following examples, the epoxidation a molybdenum catalyst is used, the proportion of which is in the range from about 0.01% by weight to 0.1% by weight Molybdenum based on the amount of reactants. The catalyst was made by that at about 82 ° C one hour o, 8 g of molybdenum powder per 100 ml of a mixture of 10% tert. Butyl hydroperoxide, 5% propylene glycol and 85% tert. Butyl alcohol was heated to reflux. Under these conditions, the molybdenum settled into a soluble, organic one Molybdenum complex compound around. This production is described in more detail in the copending application p. No. 516 described.

Example IV:

An isobutane oxidation product was obtained in a propylene epoxidation introduced that in the oxidation reactor

109882/1915 " ¹⁶ ~

was made of the stainless steel of Example I and that of about 46 wt. Butyl hydroperoxide, 48 wt% tert. Butyl alcohol and the rest of water and small amounts of other oxygen compounds duration. The epoxidation reactor consisted of a tube with an internal diameter of 1.9 cm, which had a volume of about 1o4 ml. The product of oxidation was at a rate of. 100 ml / h together with the molybdenum catalyst and 100 ml / h propylene fed.

When operated at 132 ° C and 42 kg / cur, the conversion of the tert. Butyl hydroperoxide 75%, the propylene oxide selectivity (expressed as the moles of propylene oxide formed per mole of the converted tert-butyl droperoxide) being 85 % . When operating under these conditions, the 2% aqueous solution of the sodium pyrophosphate decahydrate was added in such a way that the sodium content of the oxidation product was 40 ppm, the total amount of the sodium pyarophosphate solution representing 1% of the oxidation product and being made in the form of a single addition. Five hours after the addition of the sodium pyrophosphate solution, the conversion in the epoxidation reaction fell to 56% and the selectivity to 75%.

10 9 8 8 2/1915

Example V:

In the 24 l oxidation vessel of Example I, an isobutane oxidation product was produced at 146 ° C. and a pressure of 35 kg / cm. The oxidation product consisted of 50 wt% tert. Butyl hydroperoxide, 40% by weight of butyl alcohol, 6% by weight of water and the remainder from a mixture of smaller amounts of other oxygen compounds. When feeding this oxidation product at a rate of 100 ml / h and 150 ml / h propylene and the molybdenum catalyst in a stirred autoclave with a capacity of 265 ml, which was operated at 121 ° C and 42 kg / cm, a tert. Butyl hydroperoxide conversion of 76% was found with a propylene selectivity of 78 % .

While the isobutane oxidation vessel in the described Were operated manner, were in the reactor 75 Jnl a 2% aqueous solution of sodium pyrophosphate decahydrate and this injected solution containing oxidation product fed to the epoxidation reactor. The oxidation product contained approx. 24 ppm sodium. After the sodium-containing oxidation product has been introduced into the epoxidation reactor fell the tert. Butyl hydroperoxide wrap of

- 18 109882/1915

76% to 45 % and the propylene selectivity from 78% to 32%.

The two examples IV and V show the loss of the tert. Butyl hydroperoxide conversion and propylene oxide selectivity, when the isobutane oxidation product used in the epoxidation reaction has high proportions of Contains sodium pyrophosphate.

Example VI:

The isobutane oxidation product, which had been obtained in the operation of the 24 1 oxidation reactor carried out in the manner shown, was (before the addition of the sodium pyrophosphate) at a rate of 100 ml / h together with the molybdenum catalyst and 100 ml / h propylene in the oxidation reactor of the Example IB introduced. When operating the epoxidation reactor at 132 ° C and 42 kg / cm was a tert. Butyl hydroperoxide conversion of 74% and a propylene oxide selectivity of 88 % were obtained.

After the introduction of the sodium pyrophosphate had been started as described in Example III, was

- 19 109882/1915

obtained an oxidation product with about 2.5 ppm sodium. During the loading of the epoxidation r reaction -was neither in the tert. ButylhydroperoxydumwarwiL

faxes < y * W
There was still a change in the propylene efficiency. This example shows that by carefully controlling the alkali metal pyrophosphate feed rate, the hydroperoxide formation selectivity in the oxidation reaction vessel can be improved without affecting the yield of the epoxidation the oxidation reaction product is between 0.1 and 10 ppm, preferably between 1 and 3 ppm.

- 2o -

109882/1915

Claims (7)

P r - .. >>-;; a η s ρ r ü c Ii β 1, Process .-. Ur preparation, ^ir oii orraniüchenchen HydroperiXj.iH:], i ei which orgnnii ^ -he compounds, which a ■ h- a tertiary al iphutisches. Kohlstoi'faitrc ßci iuidenes WaGscr ^ tü.i'i '.' Jtom own and the Ι iο a11ge me ine F orme1 R-C-N have, in which R is alkyl, aryl, aralkyl, alkaryl, alicyclic or heterocyclic groups "means not catalytically oxidized in the liquid phase with a gas containing free oxygen are, characterized in that the oxidation mixture the aqueous solution of an alkali metal pyrophosphate is added. 2. The method according to claim 1, characterized in that that the amount of alkali metal pyrophosphate is calculated is that the alkali metal content of the mixture is 0.1 to 100 ppm, - 21 - 109882/1915 BAD OWÜJNAL 3. The method according to claim 2, characterized in that the alkali metal content o, 1 "to 10 ppm, based on the reaction mixture "is", 4-, method according to claim 3, characterized in that that the alkali metal content is 1 to 3 ppm, 5. The method according to any one of claims 1 to 4 characterized in that the alkali metal pyrophosphate is sodium pyrophosphate. 6. The method according to any one of claims 1 to 5 characterized in that the organic compound is isobutane or cumene. 7. The method according to any one of claims 1 to 6, characterized in that the hydroperoxide formed for Epoxidation of an olefin, for example propylene, is used by a molybdenum containing catalyst is catalyzed. 109882/1916