DE1961810C - - Google Patents

Description

1

is thrown, all boron compounds introduced into the cycle, i.e. both the boron compounds bound in the form of alcohol esters and the Excess. All boron compounds must be worked up and that which is due to "the expelled quantities (the ratio of the boron atoms to The amount of alcohol produced in moles is considerably more than 1) procedurally difficult and from an economic point of view is unfavorable or expensive. A Another disadvantage is that it is easy to waste and / or blockages because the commonly used boron compounds (ortho- and metaboric acid, boric anhydride) in the reaction medium are practically insoluble.

It is true that processes have also become known in which the amount of boron compounds is precisely limited to that amount which is necessary for the esterification of the heric-vMifn alcohol. ! κι die., - rfVerfahre- ,; the yield of the spice men per iuk _th ^. r, .- considerably lower (cf. hnn-he patent- <ichri ^i: ■ "35 625 and French patent specification

Who ^: »n processes are known / hck, - he patents .. ¹ ■ i ·. 627,984) in which in de: n R.vktionsmediur ( "Liehe boric angew: <nu!... V.jrden h β · bher.ylmetaborat in case de; ad, hexane-Oxyiia · -ii); even if it was initially ers.huni. that in this way the difficulties can be "eliminated" which result from the inadequacy of the other boron compounds in the flowing medium; so this way of working leads in turn to other technical and economic problems: it is difficult due to the fact that it is necessary to prepare separately the boric acid ester which is fed into the oxidation stage

The invention now gives the skilled person a \ erbesser'-s, simple, cheap process for the simultaneous oxidation of saturated cycloaliphatic Hydrocarbons with 4 to 12 carbon atoms in the liquid phase with the help of molecular oxygen and / or gases containing it the hand, which is carried out in the presence of boron compounds and yet not the above has mentioned disadvantages.

It has now been found that it is possible to prevent the oxidation of saturated cycloaliphatic Hydrocarbons with 4 to 12 carbon atoms in the liquid phase with molecular oxygen in Presence of any excess of boron compounds which are sparingly soluble in the reaction medium carry out and still introduce a mixture in the following process steps, which is practical free from suspended, poorly soluble excess Boron compounds is. This advance is achieved by removing the crude reaction mixture subjected to decanting before being passed on to the following process stages. As a result of the simple The process according to the invention appears to be particularly advantageous under operating conditions. A far-away The advantage is that the high yields of the desired product are the same remain while still being able to achieve significant savings in implementation of the procedure because the equipment used is simple

It also is the amount of boron compounds recovered from the crude reaction product must become. limited only to the part that actually blocks the azo alcohol produced in the form of a soluble boric acid ester !, (i.e. in the case of cyclohexane oxidation on cyclohexyl metaborate). .

The solution emerging from the oxidation stage and to be carried on in the further treatment stages no ^{longer contains any solid, poorly soluble> e} " ^c ™ solutions in suspension, so that the formation of deposits during transport is largely reduced.,

Particularly good results can be achieved if one is used to carry out the process tubular reactor used, at the booen Oxygen ~ and7 or a gas which contains oxygen and the remaining reactants (the cycio- "aliphatic hydrocarbon and the boron compound) are introduced in direct current; the supplied gas also serves to stir up the Reaction mixture. The crude reaction mixture obtained in this way is first degassed and then subjected to a clarification, so that only the clarified TeU of the reaction mixture, the corresponds to the actual formation of e.g. cyclohexanol, which is subjected to hydrolysis and the following Process stages feeds. The remaining .en

of the crude reaction mixture, which contains the entire uoerschüssige poorly soluble :; Boron compound and the in the clarification stage separated. Contains part of the reaction mixture is returned to the reactor

and introduced at the bottom of the latter.

The process according to the invention can be used in conjunction with the known oxidation in the liquid phase of saturated cycloaliphatic hydrocarbons having 4 to 12 carbon atoms, e.g. ü. Cyc c-

butane, cyclopentane, cyclohexane, cyclooctane, lyciododecane, Methylcyclopentane or methylcyclonexane. be performed.

The "procedure is carried out at high temperatures performed and at pressures sufficient to

to keep the hydrocarbon in the liquid phase.

The boron compounds that are commonly used are ^ ^env ? ^{rat 'she} ~ addition products of orthoboric z. B. Metabor

acid, tetraboric acid and / or boric acid annyona, other known boron compounds can also be used to advantage. ,around

The boron compound must be used in such an amount that the ratio of organic

atoms to the prepared Alkolio amount in moles in the reaction mixture is greater than 1 and to present ₀ so that good yields is sweise greater than 1.5, obtained

will. .

Theoretically, there is no upper limit to the ratio mentioned; excellent results will be obtained when the value of the ratio is between 2 and 3.

Oxygen, air and / or gases, the molecular oxygen, are suitable as oxidizing gases

contain. The inventive method can can be carried out in any apparatus so far one has, for example, autoclaves with mechanical stirrers were used, in which the decanting chamber or zone

is installed outside the oxidation chamber. It However, differently designed devices can also be used, provided that sic Lint is arbitrary have designed chamber or zone in

which part of the reaction mixture, which clogging of the pipelines and similar difficulties

corresponds to the formation of the desired alcohol, can be avoided.

can be decanted while the excess The following examples serve to further elucidate

Boron compounds introduced into the oxidation stage purify the invention.

has been removed before the solution passes the ό The first attempt at which the clarification stage fails ;,

is fed to the following stages of processing. is listed for comparison purposes. Not so far

In the drawing, a preferred embodiment is expressly indicated, something else is

form of the process according to the invention and the amounts given in the examples

Device according to the invention shown. by parts by weight and percent by weight

A tubular reactor 1 contains the reactivity v · «.!.;. *« «« «*

mixture, what! essentially from the non-comparison experiment

converted hydrocarbon, the boric acid ester A reactor of the one shown in the drawing

of the alcohol formed, smaller amounts of keto type, in which, however, the clarification chamber 4 is omitted

and by-products as well as, finally, which had been transferred and the pipes 3 and 5 in direct

The remaining boron compound (e.g. metaboric acid), which was the 15th compound, was mixed with a mixture

Slightly soluble in the reaction medium and as a result of 9 parts of metaboric acid to 100 parts of cyclohexane

whose suspended exists. fed.

The reactor is from the bottom through the Ld- 2000 parts of cyclohexane per hour, 150 parts lines 6 and 7 are fed, namely the metaboric acid per hour and the oxidizing wtr hydrocarbon, which suspends the boron compound * o kende gas, which consists of a mixture of 5 volumetric ions (in an amount that essentially corresponds to the amount of oxygen and 95 percent by volume nitrogen which corresponds to the clarified in ester form, were continuously fed into the mixture of a further process stage of the part of the re-fed. At the same time, Ober became the one in the character action mixture is included), and the fiung dashed line 11 α an approximately oxidizing gas continuously and in cocurrent * $ the same amount of product continuously withdrawn and initiated hydrolyzed with the same amount of water

The crude reaction mixture then passes through the chamber at a temperature of the upper end of the reactor in the degassing chamber 165 ° C and under a pressure of 8 kg / cm *. The gases and vapors are passed into this chamber. The usrarssdtesgsgrsd was separated off from the other products by reg. boric acid to cyclohexanol in the reaction mixture borrowed nitrogen, CO ₈ , O _x , etc.) according to the corresponding, which corresponded to about 2 * 3. Treatment escape. The experiment was terminated after 100 hours. The condensed products get into a 3-cell. Analysis of the reaction products showed that separator M, at the bottom of which the water of reaction had consumed 174 parts of cyclohexane per hour, was drawn off. The unconverted organic were, which corresponds to a conversion (= · / · used phase is withdrawn from the upper end and cyclohexane in moles to · / · added cyclohexane back into reactor 1. In moles) of 8.7 · / ·, based on supplied cyclo- The greater part of the 40 hexane degassed in this way corresponds to the organic oxidation phase of the crude reaction mixture is via the pipeline (2035 parts per hour), which is produced by hydrolysis of the gene 3 and 5 and through the decanting chamber 4 in from the reactor withdrawn product was obtained with water, the lower part of reactor 1 (oxidation zone), contained in addition to a small amount Alcohol 45 cyclohexanone, which corresponds to a total molar yield, corresponds to the poorly soluble boron compounds of 86.8 * / Cyclohexane); the weight ratio of alcohol to Zoss formed in clarification chamber 4. Ketone was 14.4. The aqueous hydrolysis phase J The clarified product is fed through line 11 continuously containing 13.0 · / · Orthobornuierikh to the following treatment stages; 50 acid. The ratio of boron atoms to moles of cyclic or part enriched with sparingly soluble boron compounds hexanol in the product (e.g. metaboric acid) withdrawn from the reactor was consequently about 2.5. The total line S λ fed back the reactor 1 amount of the In ar recovered after the hydrolysis. The apparatus described below are used and orthoboric acid fed to the dehydration has no mechanical gears for stirring the 55 was 1.5 kg per cyclohexanol plus cyclohexanone. Mass required, weü a stirring or thorough. mixing by the supplied oxidizing gases itself example is achieved. Devices of the type described ^{T in} a reactor of the type shown in the drawing can also be connected in series, so th type, which had the clarifying chamber 4, so that two or more oxidation chambers 60 can be arranged one after the other under the conditions mentioned above. In such a case carried out; However, the amount supplied was 75.4 parts per hour of metaboric acid in the clear zone or clear chamber, ie, positioned behind the last oxidation reactor only spoke the amount required for the esterification of the; In general, however, it is more favorable if a produced cyclohexanol is necessary. The Versolcbe chamber behind each individual oxidation search was terminated after 107 hours. The step to be provided so that the transport of mixtures analysis of the reaction products showed that the gene, the poorly soluble boron compounds in suspen- Cydohexane consumption was at 182 parts per hour ston, and thus a clogging or a and thus a conversion of 5 , 1 · / ·, based

(ο

on supplied cyclohexane, corresponded. The organic oxidation phase (2035 parts per hour), which was obtained by hydrolysis of the product withdrawn from the clarification chamber with water, consisted, in addition to small amounts of by-products, of S 8.59% cyclohexanol and 0.59% cyclohexanone, which is a molar amount total yield of 86.3 ⁰ O, based on converted cyclohexane corresponded; the weight ratio of alcohol to ketone was 14.5.

The aqueous hydrolysis phase (2000 parts per to hour) contained 5.4 · / o orthoboric acid. The relationship of boron atoms to moles of cyclohexanol in the clarified product was consequently close to 1; the total amount of orthoboric acid recovered by hydrolysis and sent to dehydration was about 0.6 kg per kilogram of cyclohexanol plus cyclohexanone.

With the help of the method according to the invention, which has a clarification zone, it is consequently possible carry out the oxidation even with a very large excess of metaboric acid and yet at the same time to withdraw a reaction product that contains only an amount of metaboric acid that is approximately corresponds to the same amount that is necessary for the esterification of the cyclohexanol.

In this way, with the same degree of conversion and the same yield, the amount of orthoboric acid which has to be worked up (hydrolysis and subsequent dehydration) is about 0.9 kg per kilogram of cyclohexanol plus cyclohexanone produced lower. The absence of a solid phase in the product withdrawn from the reactor also avoids the formation of clogging conditions and deposits in the apparatus .

1 sheet of drawings

Claims (1)

1 2 formation of boric acid esters against further oxidation Patent claim: to be protected (see USA patents 1 931 501 and 1 947 989). Process for the continuous oxidation of In this context, for example cycloaliphatic !! Hydrocarbons with 4 to 5 carry out the process for the production of alcohols 12 carbon atoms in the liquid phase with oxidation of paraffins or waxes in the liquid molecular oxygen and / or gases that siget. Phase with air in the presence of orthoboron sen contain, in the presence of at least one in acid or boric anhydride are pointed out Reaction medium sparingly soluble boron compound (A. N. Bashkirov et al., Contribution on the occasion of in one or more consecutively arranged 6th WPC in Frankfurt / M., on June 19 to 26, 1963, Neten reactors, hydrolysis of the Oxy-Sect obtained. IV, Paper 38-PD 9, pp. 1 to 6, as well as Neftekhi dation mixture and recirculation of dehydratimaya, 1, no. 4, 517 [1961], p.414 to 422). The use of orthoboric acid in the oxy- characterized in that one is a dation of cyclododecane in the liquid phase essential part of the crude reaction mixture 15 has been described for a process in which decanted before carrying out the hydrolysis, the molar yield of cyclododecanol-cyclododecanone- clarified part of the reaction mixture of the hy- mixture in the order of about 90 mol- drolysis> in the subsequent process percentage; the alcohol-ketone ratio in that fen and the separated suspension of the mixture is about 10 (Italian patent sparingly soluble boron compound in the reactor 643 401 and Japanese patent specification 11 121/62). returns. More recently, orthoboric acid has also been used or other border derivatives, especially metaboric acid and other less hydrated ones Forms of orthoboric acid in the oxidation of as cyclohexane ik. the liquid phase has been described. The latter procedures are for practice The invention is an improved Ver particularly valuable because it allows the production of drive to allow continuous oxidation of saturated alcohol-Kcton mixtures in yields, ten cycloaiip-.atic hydrocarbons with 4 to which are significantly higher than in processes that are in 12 hydrocarbons carried out in ier liquid phase with 30 absence of boron compounds Help from molecular oxygen and / or gases. which contain this, in the presence of at least the industrial application of the above-mentioned associations Boron processes, which are sparingly soluble in the reaction medium, are associated with some disadvantages, binding in one or more consecutively which the actual possibilities largely orderly reactors, restrict hydrolysis of the obtained 35. Oxidation mixture and recycling of dehydra- These disadvantages are based to a considerable extent tized boric acid in the oxidation calls, this is due to the fact that it leads to high yields is characterized in that a substantial part of the desired products is necessary, the to use the crude reaction mixture before carrying out the boron compounds in amounts that far Hydrolysis decanted, the clarified Te ^- U of the reac- 40 are above the stoichiometric ratio, the tion mixture corresponds to the hydrolysis and the subsequent reaction. It goes without saying that the process stages and the separated it for the economic implementation of such Suspension of the sparingly soluble boron compound is necessary in the process, the entire used Reactor returns. Recover boron compounds and in the With the help of the method according to the invention, the cycle can be returned and the losses as far as especially mixtures of cycloaliphatic !! possible to limit. Alcohols and ketones with a high alcohol content However, it is known to every person skilled in the art that they win most. Such mixtures are valuable domestic end of such Oxydationsverfahreii hydrolysis dustrial products. They may, for example, the reaction product (with either water or the production of intermediates for poly 50 with aqueous solutions of H ₃ BO ₃₎ is performed amide fibers, for example, adipic acid or caprolactam . ν "γ- will be turned to the alcohol, which is in the form of boric acid. esters is present, to be separated and the boron compound. Several processes are already known which can be used to recover. During the hydrolysis, the preparation of mixtures of alcohols and Ke- boron compounds in the form of orthoboric acid are used; these procedures are based on the par- 55 wunnen. Because it has been shown that metaboric acid tietlen oxidation in the liquid phase of saturated and other less hydrated forms of orthotics, especially cycloaliphatic hydroboric acid, which are most active boron compounds in the oxidation of hydrocarbons (cf. IV Berezin et al., The Oxidation of substances , becomes the cyclohexane ”, pp. 273 to 279, Pergamon Press, Ox- recovered orthoboric acid before recycling ford, 1966). 60 in the oxidation process of a partial dehydration Some of these processes have recently become subject to modification. very interesting from an industrial point of view. namely those who use hydration of boron compounds are extensive Boron compounds are carried out. It has been rich and associated with certain difficulties, It has long been known that it is possible in this way, 65 In the previously known processes, the raw significantly higher yields of the desired reaction mixture, which consists of the oxidation alcohol Achieve because by using the reactor drained and before being passed into the Boron compounds the alcohols formed by further treatment stages of hydrolysis