US939584A - Process of manufacturing benzoate. - Google Patents

Description

UNI ED sTATEs PATENT oFFIoE.

EDWIN 0. BARSTOW, or MIDLAND, MICHEGAN, .AS'SIGNOR TO THE now CHE ICAL COMPANY, OF MIDLAND, MICHIGAN, A CORPORATION or MICHIGAN.-

rnoonss or MANurAo'rimINe BENZOATE.

No Drawing.

Specification of Letters Patent. Y Patented Nov. 9, 1909, Application filed October 25,1905. Se1-ia1No.284,402.

To all whom it may concern: I

Be it known that I', EDWIN O. BARS'IOW, a citizen of .the'United States, resident of Midland, county of Midland, and State of Michigamhave inventeda new and useful Improvement in Processes vof Manufacturing Benzoates,.of which the following is a specification, the principle of the invention bein herein explained and the best mode in whic I- have contemplated applying that.

rincip'le, so as to distinguish it from other inventions. p

' M invention relates to processes of making 'enzoic acid and benzoates and particu larly to the manufacture of calcium benzoate;

'Said 'in'vention consists of 'ste s hereinafter fully described and speci cally set forth in the claims. j

The following' 'description. sets forth in detailcertain steps embodying myinvention', such disclosed steps constituting but-one of various ways in-which the principle of the invention may be used.

Some of the" various methods by which benz'oic and benzoates have heretofore been manufactured are as follows: (1) 'from gum' benzoin and other natural gums by sublimation or extraction, such-processes in-f volvihg the treatment of the gum simply with heat, or with an alkaline solution to dissolve the benzoic acid,-and the subsequent precipitation by means of a mineral acid; (2) from urine and hi puric acid b well known processes; (3) om benzyl c lorid, benzal chlorid or benzotri-chlorid, by the following processes: (a) from benzyl chloridby oxidation withhot dilute nitric acid, givingas resultant products benzoic acid and hydrochloric acid; (b)from benzal chlorid as. a by-product in the manufacture of benzaldehyde, the benzal chlorid being treated withasolution of lime; (c) from ben'zo-triichloridby heating with water .un'derpres sure, with lime and water or a solution of caustic soda and whiting.

My invention relatesto-those of the above- .mentioned methods in which benzoic acid or the benzoates are manufactured from homologuesof benzene containing one side chain, and particularly to that method in which calcium benzoateis manufactured from benzyl chlorid, although the broad spirit. ofmy invention comprehends the manufacture of. benzoates from 'benzal chlorid; also from products of toluene and calicum benzoa-t'e, as

acid or benzoates. When manufactured-flay chlorid, the old process is subject to the difficulty that the resultant product always contain's impure acids in the form of chlorbenzoic acids. I

product ofone of the homolognesl ofben- ,zene, such product having only one side chain,"and"then I oxidize such product to benzoic acid or a henzoate by means of a compound containin chlorin. Hou' e\ 'e,r, ,lj

would consist of only one step, v1z., the oxidation of such product by the chlorincontaining compound.

In order to typify the methods by which my process may be effected I shall describe that derivative of toluene whichf'has bne by means of bleaching powder, and lime. It will be understood, however, that other ing from the spiritflof my invention.

When toluene ,is chlorinated to the first stage, either benzyl chl'orid .Jr a chlortoluene is formed and the tendency is for each molecule of the toluene to take one atom of the chlorin before any molecule takes a second atom, this atom of chlorin going into the-side chain or methyl radical of the toluene in a great majority of cases,

benzyl alcohol, benz-aldehyde, and other products. intermediate of the chlorination is particularly pointed out and claimed in my copendingapplication for U. S. Letters In the carrying out of my iinproyed, process I produce a chlorin substitution the same as carried out when manufacture V which is unsatisfactory when the main pnrpose sought is the manufacture of bCllZOlC the old method noted above from benzo-trimay start with the clilorin substitutionprod; not and in that case my improved process.

atomof chlorin in one. side chain, '\"i z..,' benzyl "chlor1d,..and thenoxid ze/the same ioif compounds may be utilized without departchlorin, whatever it I took up two atoms if the conditions under which the -chlorination takes place are proper, such conditions being principally that the chlorination be aided by heat and take place in the sun light. If the chlorination is and dark, or there be present any carrier .such as iodin or ferric chlorid, the chlorin the part still remaining as a liquid. When the chlorin atom that is taken up goes into the side chain, it forms benzyl chlorid, and when it goes into the ring, as it does in a comparatively few cases, it forms a chlortoluene. This chlor-toluene will not form a benzoic acid when treated according to my process, so that it will not form an impurity in my resultant product, I therefore obtain a benzoate which holds very little ring does hold being obtained from those few molecules of toluene which of chlorin, of which two atoms one went into the rin and one into the side chain; because, it both of the chlorin atoms or all three of them, if some molecules of toluene had taken up three atoms, had gone into the ring, theyv would not form a benzoic acid at all, or, if they had gone into the side chain, the would have formed a benzoi c acid containing no ring chlorin. 4O

It will be understood, therefore, that if I pass into the toluene only such a quantity of chlorin as is necessary to furnish each molecule with one atom, toluene will be chlorinated to the first in the manner described above, and 'by far the greater part of-it will be in the form of benzyl chlorid, the remaining smaller part being in the form of'chlor-toluene, which latter is inert, when I oxidize, ashereinafter fully described, and, consequently does not form a chlor-benzoic acid which would be an impurity in the resultant product. It will be seen, therefore, that if I should chlorinate the toluene to the second or third stage, the probabilities would be greatly increased of obtaining a. product in which chlorin had entered both the ring and the side chain of the toluene, and thus result, when the oxidation is effected, in the production of a chlor-benzoic acid, as noted above. Another objection to the chlorination of the toluene to the secondstage, viz: to benzalchlorid or to the third stage, viz: to benzo-tri-chlorid, is that much stage efiected in the coldsubstantially all of such more aptoluene with paratus is required to treat. a given amount sary to have of toluene in a given time, which is uneconomical since the chlorination of toluene is atthe best. a delicate and comparatively expensive operation. Furthermore, the rate of absorption of the chlorin is much faster during the first stage of the chlorination than it is during the later stages; also, the loss due to decomposition is not nearly so great when benzyl chlorid is formed as it is when benzotri-chlorid is formed, due to the fact that the liquid remains in the apparatus less than one-third as long, "and also to the fact that under the conditions benzo -tri -chlorid decomposes more readily than benzyl chlorid. My improved process, then consists in chlorinating toluene to the first stage, viz. to benzyl chlorid and then heating the latter with a solution of bleachin powder and lime, calcium benzoate thus icing formed, which crystallizes out upon cooling the solution. Sodium benzoate may be obtained by adding a solution of sodium carbonate to a hot solution of calcium benzoate. If the chlorination hasreached the second stage, calciuin'benzoate may be obtained from the benzal chlorid by heating the latter with a solution of bleaching powder and lime.

As a guide in practically making out my process, the following data, illustrating the relative quantities and course of procedure where the-specific materials named are employed, is furnished. One part of benzyl chlorid is agitated with three parts of water to form an emulsion and then is run into a solution made by dissolving three and one-half parts of bleach in twenty parts of water and thereupon adding one-third part of slaked lime. Upon heating and stirring this mixture in a suitable apparatus calcium benzoate isformed according to the following reaction The apparatus preferably employed consists of a common cement-lined iron retort provided with a reflux condenser, an agitator, and direct steam and water connections for regulating the temperature. The. preferred temperature is about 95 C.

Bleaching powder or chlorid of lime is made by absorbing chlorin in slaked lime andthe oxidizingconstituent of bleaching powder may be regarded as having the formula CaOCh. However, the latter may be regarded as a -'mixture in equal molecular proportions of, calcium chlorid and calcium hypochlorite, thus:

and in this case the calcium hypochlorite would be regarded as the active oxidizing constituent. In oxidizing a derivative of bleaching powder it is neceslime present in order to neutralize the benzolc or hydrochloric acid as soon as formed and. thus keep the solution always alkaline. Otherwise, if the solution is allowed, to become acid the bleaching powder is \decomposed with liberation of free chlorin and conversion of the hypochlorite into chlorate and chlorid. Since ordinary bleaching powder always contains a considerable amount of caustic lime, it is possible to efi ct the oxidation of the benzylor alkaline earth hydrates either in solution plete conversion to benzo-tri-chlorid, such or in the solid state. As an example of the foregoing. sodium hypochlorite is obtained, which is an active oxidizing agent, when chlorin is absorbed in a. solution of sodium hydrate, thus:

QNaOH-t-Ch:NaClQt-NaOCl-t-HQ.

This method, in which alkaline hypochlorites are utilized as the oxidizing agents, is

particularly pointed out and claimed in an.-

other co-pending application for U; S. Letters Patent, Serial No. 305,958, filed March- I prefer to use lime as the reagent. with which to neutralize'the acid formed, but it is not, necessary to do so, since I can use the hydrate of any alkaline or alkaline earth metal. Furthermore, I prefer to use toluene as the source of benzoic acid, but

any of the homologues of benzene contain .ing one side chain wlll serve the purpose.

The gist of my invention, then, consists in the oxidation of the derivatives of members of the benzene series of hydrocarbons by means of bleaching powder, or similar hypochlorite containin g substances, such deriva tives, as benzyl chlorid, benzal chlorid, benzaldehyde, benzyl alcohol or any of the side chain deriyatives .of the homologues of benzene which require oxidation to form benzoic acid, being obtained in any desirable way.

It wlll be noted that while I prefer to stop the chlorination of the toluene at the first stage, viz., at the formation of benzyl chlorid, it is not necessary to do so, but that I can stop'at any point short of the comchlorinated toluene then being in the form of a mixture of toluene, benzyl chlorid, benzal chlorid, benzo-tricl1lorid, and small amounts of decomposition products and compounds. with chlorin in the ring, this mixture, upon being treated with a solution of bleaching powder and lime, being oxidized. directly .to calcium benzoate without further chlorination, which further-chlori-' nation would give a protlnctyielding a less pure calcium benzoate." I prefer totrea-t' the chlorinated toluene. directly with liine and bleaching powder, but Imight convert 'the chlorids of toluene into intermediate products; and then oxidize'the lattertobenzoates, for instance, converting benzyl chlorid into benzyl alcohol by heating with a solution of sodium carbonate or by any other suitable method, and converting benzal chlorid into benz-aldehydewith'a limesolution, and then oxidizing the benz-aldehyde into benzoic acid'by means of bleaching powder. any: oxidation to form benzoic acid and hence my process is not 'applicabl'e thereto.

'By my improved processl obt-ain' a pure benzoic acid, due to thesm-all percentage of chlorinated toluene which contains it's chlorin both in the side chain and in the ring; furthermore, in order toiobtain a given amount of benzoates, require less than onethird of the apparatus and only one'third of the amount of chlorin gas t-liatfhasbeen necessary heretofore when the toluene was Ben'zo-trichlorid does not require converted into benzo-tri-chlorid, the remain- 'n oxidationfbeing effected means of ,hIorid of lime which is easily. and cheaply made by absorbing chlorin in 'slaked lime.

' It has been stated that the class of compounds which my improved", process is ada ted to utilize as a starting point for the oxi ationstep, that constitutes the process proper, is merely exemplified in the .benzyl chloridl The members of the general class of compounds available -for use in the process may be appropriately denominated, sidechain-substitution products of afme'mber of the benzene series ofhydrocarbons, where by such term I mean hydrocarbon derivatives in which one or more hydrogens of a side-chain have been replaced either directly or indlrectly by chlorin, oxygen, hydroxyl,

or similar elements or radicals. Thus in its I specific aspects the present application deals with a side-chain substitution roduct in which chlorin figures as the substituting element; While in the companion application,

Serial No. 305,959, referred to abo 'e, a

product in which the hydrogen is. similarly replaced by hydroxyl is employed. The sub-.

type of product-{exemplified .in the .latter case, While included in the generic term above defined-{has for the purpose of such companion ap lication been called a partially oxidize oxygen-containing product of a member ofthe benzene series of hydrocarbons.

"Having described my invention in detail, that which I particularly point out and distinctly claim is:

1. In a process v of manufacturing 1 beni zoates, the step which of a member .to the acid a side-chain substitution product zoates, the step carbons, by means of bleaching powder in consists in oxidizing lo the acid a side-chain substitution .product of a member of the benzene series of hydrocarbons, by means of a chlorin-containing reagent in the presence of a basic neutralizing reagent and a suitable solvent.

2. In a process of manufacturing benzoates, the step which consists in oxidizing to the acid a SldG-Clmlll substitution product of the benzene series of hydrocarbons, by means of a chlorin-containing reagent in the presence of an alkaline earth hydrate and a suitable solvent.

3. In a process of manufacturing benzoates, the ste which consists in oxidizing of a member of the benzene series of hydrocarbons, by means of a ehlorin-containing reagent in the presence of lime and water.

In a process of manufacturing benwhich consists in oxidizing to the acid a side-chain substitution product of a member of the benzene series of hydrothe presence of a suitable solvent, such bleaching powder containing sufiicient lime to neutralize the acid formed by the reac-. tion.

In a process of manufacturing benzoates, the step which consists in oxidizing to the acid a side-chain substitution product of a member of the benzene series of hydrocarbons, by means of bleaching powder in the presence of water and of lime in excess of that contained in said bleaching powder.

6. Ina process of manufacturing ben-- zoates,- the step which consists in oxidizing to the acid a chlorinated derivative of a memberof the benzene series of hydrocarbons, by means of a chlorin-containing reagent in the presence of a basic neutralizing reagent and a suitable solvent.

7.- In .a process of manufacturing benbons, by

zoates, the step which consists in oxidizing to the acid achlorinated derivative of 'a' member of the benzene series of hydrocarbons, by means ofa chlorin-containing reagent in the presence of an alkaline earth hydrate and a suitable solvent- 8. In a process of manufacturing benzoates, the step which consists in oxldizing to the acid a chlorinated derivative of a member of the benzene series of hydrocarbons, by means of a chlorin-containing reagent in the presence-of lime and water.

9. In a process of manufacturing beni zoates, the step which consists in oxidizing to the acid a chlorinated derivative of a member of the benzene series of hydrocarmeans of bleaching powder in the presence of a suitable solvent, such bleachpowder containing sufficient lime to neutralize the acid formed by the reaction.

10. In a process of manufacturing benzoates, the step which consists in oxidizing to the acid a chlorinated derivative of a member of the benzene series of hydrocarbons, by means of bleaching powder in the presence of water and of lime in excess of that contained in said bleaching powder.

11. In a process of manufacturing ben- =zoates, the step which consists in oxidizing benzyl chlorid to 'the acid by means of a chlorin-containin reagent in the presence of a basic neutraIizing reagent and a suitable solvent.

12. In a process of manufacturing benzoates, the step which consists in oxidizing benzyl chlorid to the acid by means of a chlorin-containing reagent in the presence of an alkaline earth hydrate and a suitable solvent.

13. In a process of manufacturing benzoates, the step which consists in oxidizing benzyl chlorid to the acid by means of a chlorin-containing reagent in the presence of I lime and water.

14. In a process of manufacturing benzoates, the step which consists in oxidizin benzyl chlorid to the acid by means of bleaching powder in the presence of a suitable solvent, such bleaching powder containing suiiicient lime to neutralize the acid formed by the reaction.

15. In a. process of manufacturing benzoates, the step which consists inoxidizing benzyl chlorid to the acid by means of bleaching powder in the presence of waterand lime in excess of that contained in said bleaching powder.

16. The process of manufacturing benzoates, which consists in forming an emulsion of benzyl chlorid with water, mixing such emulsion with a solution of bleaching powder and water to which has been added a quantity of slaked lime, and thereupon heating.

Signed by me this 17 day of Oct. 1905.

' EDIVIN O. BAR-STOW.

Attested by- 'Inos. GnIswoLD, J12, CARL IV. BENNETT.