US2506457A - Dehalogenation process - Google Patents

Description

Patented May 2, 1950 Shre'wsbury N. JQ, assignors to Nopco' Chemical Company, Harrison, N. J ,a corporation of New Jersey Nol rawing. ApplicationF-ebruaryii; 1949 Serial No. 733486 14.'Claims'.- If

This invention relates to: a-- dehalogenation process and. more particularly: toa highly improved process for dehalogenating:oxidized halo.- genated sterol. compounds.

It has been known for a number of years that halogenated organic" compounds:- coul d be dehalogenated to produce unsaturated? organic compounds by reactingfthe halogenated compounds with ziricin: the presence ofla short chain organic acid such as acetic-a'cidi. Thus in U'. S;.Patent No. 1-,254,866=there is-discloseda process for producing hydrocarbon;oilssuitable. for use as drying oils'wher'ein av natural hydrocarbon oil first chlorinated: and: then the chlorinated oil is reacted with. zinc: inthe presence" of. acetic acid in order to dehalogenate thechlorinated oil, thus providing; a highly unsaturated hydrocarbon-oil suitable for use in the paint industry.

Another example-ofthe-useof zincz'as-a dehalogenating': agent is in. the: production of purelinol'eie acid from tetrabromestea-ricacid. Since the various fatty acids have physical and chemical characteristics which. are: closely related, it is rather different to recover the. individual fatty acids inpure'form from natural fatty materials. However. linoleic acidmay be: recovered-1 in pure formby completely: saturating with halogen atoms the double-'bonds or. all the compounds in a-fatty mixture'containing linoleic acid; separating by fractional crystallization the tetrahalostearic acid,. which-wasformed by the halogenation of the linoleic acid-3. from the. other halogene-ted fatty'materials themix-ture; andsubsequently dehalogenatingi the tetrahalo-stearic acid tore-form pure linoleic acid; It is possible to recover pure linoleic acid by such a means because of the fact that the tetrahalo-stearic 'acids ha-ve meltinepoints which are rather sharp and which. are separated. from: the. melting: points of the otherhalogena-ted fatty acids byasubstantial number of degrees'of temperature.

Another illustrationeof the use of zincas a dehalogenating. agent. may be. found. in the: art of sterol\ chemistrywherein cholesterol and similar sterols areemployedto produce the sex hormonesand various intermediatesuseful in the preparation. at the sex. hormones. Dehalogenation processesrusing: zincfit into f these processes since. in these processes cholesterol.- and other sterol' compounds are first completely halo-- a split offi the-alkyll -side chain of the sterol cornpound; and after such" oxidationhastakenplace, the oxidized halogenated compound which is'obtained is dehalogenated; to form the desired intermediate or the desired sex hormone. Also in the sterol field, it is rather common practice to recover stigmasterolfrom the mixture of sterols present. in soybean oil by saturating. the double bonds of the compounds' in suchmixtureof sterols with halogen atoms and thereafter subjecting this halogenated: mixture to fractionalcrystallization- The halogenated stigmasterol may be readily separated from the: other sterols; in such mixture. because of the varying solubilities of these halogenated compounds: The recovered halogenated stigmasterol. may then be subjected to dehalogenation with zincto-re-form. the pure stigmasterol.

It is thus seen; that there. are a: number of valuableapplications of. the use of. zinc as-adehalogenatingagentfor halogenated-organic compounds. Inallcases in the prior art,v as far as We are aware in which. zinc in the presence of.. a short chain organic acid is usedas a deha'logenating. agent in such processes, the dehalogenation is. carried-v out by admixing-the halogenated compound with zinc: and the short: chain organic acid, e. g. acetic acid, in some suitable vessel, preferably in a vessel to which heat is applied. This is particularly true in the dehalogenation of themixtures. resulting from the chromic acid oxidation of halogenated cholesterol compounds and similar sterolcom-pounds in processes for the production of sex hormones and intermediates suitable for the production of sex hor- Thus: in an. article published by Wallis and Fernholz, J. A. C. S. 57', 1504-6- (1935),. such a dehalogenation is carried out by admixing the oxidation mixture resulting from the chromic acid oxidation of chol'esteryl. acetate dibromide with acetic acid andpowdered zinc in a. suitable vessel: and heating this reaction mixture at about 100 C. for a periodiof about. two hours In U. S. Patent No. 2,180,095., which discloses. the production from. cholesterol and similar sterols, such as sitosterol and stigmasterol, of intermediates useful. for the production. of. sex hormones, a similar dehalogenationprocess is disclosed.

The prior art. processes. for dehalogenating halogenated compounds with. zinc have. in most cases given very good yields of the desired dehalogenated compounds. importantv exception, however, isin. the dehalogenation of the halogenated compounds. which arepresent. in the reaction mixtures. resulting. from. the chromic acid oxidation of halogenated. sterol' compounds. It

sterol nucleus. preventing such splitting or destruction or" the 3 is not known just exactly why in the latter case the prior art processes do not give as good yields as desired but since the halogenated compounds are in contact with the zinc for a considerable period of time, it is entirely possible that a number of undesirable side reactions occur during the dehalogenation process which produce compounds other than those desired, thus reducing the a'"- I tual yield to an amount less than that theoretically obtainable. This is probably accentuated to a considerable degree by the complexity of the mixtures resulting from the oxidation of halogenated sterol compounds. Furthermore the presence in such oxidized mixtures of many'compounds other than the desired oxidized halogenated sterol compounds probably has a detrimental effect upon the dehalogenating agent reducing its efliciency and thus reducing the yield of the esired dehalogenated compounds. The longer the dehalogenating agent is in contact with this highly diverse mixture, the greater will be the reduction in its efficiency. Such an adverse effect would be an important factor in the prior art processes because of the relatively long periods of contact between the halogenated compound and the dehalogenating agent in such processes.

It is known, of course, that chromic acid oxide. tion of sterol compounds produces mixtures of compounds which are of a highly diverse nature and which usually contain only small amounts of the desired compounds due to the fact that it is not possible to control accurately the oxidation of the halogenated compounds so as to produce the desired oxidized materials. In other words, the oxidation, which is very severe, does not always proceed along the desired lines. ases the halogenated sterol compounds which In many are being oxidized may be split somewhere in the In fact it is for the purpose of sterol nucleus that the sterol compound is halogenated in the first place since if the double bond or bonds in the sterol nucleus were not protected by some means such as halogenation thereof,

splitting of the sterol nucleus at the double bond would occur in every case, thus resulting in a complete failure to produce any of the desired compounds.

It is the object of this invention to provide an A improved process for dehalogenating halogen-' ated sterol compounds which have been subjected to oxidation with chromic acid.

A further object of the invention is to provide a process for dehalogenating halogenated sterol l compounds which have been subjected to oxidation with chromic acid which will give substantially higher yields and which will be simpler in operation than present processes for dehalogenating such materials.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

It has now been discovered that the above and other objects of the invention may be accomplished by carrying out the dehalogenation of an oxidized halogenated sterol compound by aproc ess which comprises dissolving the halogenated compound in a short chain organic acid which acid, if desired, may be admixed with up to about two and a half volumes of a suitable fat solvent,

Such a dehalogenation process gives much pound than prior art processes; furthermore, the equipment necessary to carry out this process is simpler than that required in the prior art processes and it requires less operating space than the prior art equipment. The cost or" carrying out the process by this means is less-than in the prior art processes since not only is" the equipment which is used less expensive and less expensive "to operate but also by admixing the zinc with a suitable inert material the amount of dehalogenating agent which is required will be less than that which must be used in order to carry out the dehalogenation in accordance with the prior art methods.

The process of the present inventicnis eminently suitable for use in dehalogenating any of the halogenated compounds present in reaction mixtures formed by the chromic acid oxidation of haolgenated sterol compounds. Thus the process of the invention is quite valuable for use in processes for the production of androsterone, cholenic acid, hydroxy cholenic acid, hy droxy norcholenic acid, and hydroxy bisnorcholenic acid and other compounds suitable for use as intermediates in the production of sex hormones. It is well known,'of course, that sterol compounds prior to being oxidized with chromic acid are treated so as to convert the free hydroxyl group at the 3 position to some group which will not be affected by the oxidation reaction, for example, an ester group or an ether group. For the purposes of the process of our invention, it is im' material, of course, how the 3 position of the halogenated sterol is protected during the oxidation reaction. The most general practice, however, as is well known, is to form either the acetate or benzoate ester of the sterol, and then to subject the halogenated product formed from such ester to the oxidation reaction. Also, as far as the process of our invention is concerned, it makes little difference as to which particular sterol is used as the initial starting material as long as it is one from which products are made by oxidizing a halogenated derivative thereof. At the present time cholesterol is the sterol most frequently used as a starting material in such processes. Sitosterol, stigmasterol and similar sterols are also quite useful in producing valuable derivatives by means of such oxidation reactions. In every case where the dehalogena- -tion of such oxidized halogenated sterol comcompared to the yields obtained by the prior 'art methods.

The dehalogenation process of our invention is carried out by dissolving the oxidized halogenated compound in a solution made up either completely of a short chain organic acid or of a mixture of a short chain organic acid and a suitable fat solvent. This acidic solution of the oxidized halogenated compound is then passed through a column which is packed with zinc or which is packed with a mixture of zinc and some inert material. The short chain organic acids which we prefer touse in the process of the invention to dissolve the halogenated compounds mixtures of these acids.

are acetic acid and propionic acid or suitable If desired, there may be admixed with such an acid up to about two and a half parts of a suitable fatsolvent for each part of acid. Thus rat solvents such as ethyl eth-er,- halogenated hydrocarbons suchas arease methylene chloride, ethylene chloride; ethylene dichloride; etc.-, esters such as methyl acetate and-ethyl acetate; ketones such asacetone, etc, may beemployed. The amountof organic'aci'd or mixture of organic acid and-fat solvent which is-used as the solvent'in relation-to theamount of halogenatedcompound-which-is to be dehalogenated may vary, although usually it ispreferrednot to employ any more solvent or solvent mixture than is necessary to -completely dissolve the halogenated compound which-isto be dehalogenated but, if desired, -lar'ger. amounts of solvent may be employed. It might be thought that the use ar a-halogenated fat solvent inithe process would result in dehalogenation of'such fatsolvent and thus interferew ith the dehalogen-anon of the 'compound 'which itilis'desired to dehalo'genate} however, the: halogenated fat solvents which are employed' contain" their: halogen atoms in a much stronger chemically bound condition than the halogen in the halogenated compounds which it is desired to dehalogenate and therefore no detrimental results are obtained by the-useof such solvents.

The'column which is employed in the dehalogenationprocess-ispacked with zincmetal or a mixture of zinc metal and some inert material such as siliconcarbide (sold under the trademark of Sarborundum), glassor other suitable-inert packing materials. It hasbeen found that such inert material may be admixed with the zinc metal in-l1flt0-a5 muchas-equ'al parts ofinert material per each-part of zinc without detrimentally affecting the results which are obtained. In fact, it is preferred to employ at least one part oi such an inert packing material for each'two parts of zinc since we have found that higher yields of the desired dehalogenated compounds are obtained when this is done as compared to when thecolumn is packed entirely with zinc. The'exactreasons for such higher yieldshave not been determined but We have found that such is actually'the case. It may be that the'inert" material aids in keeping, the packing in the column in a porous condition thus insuring a rapid flow of the solution of the halogenatedcompound through the column. Furthermore; we have also found that by packing the column with such'ine'rt material the amount of zinc which is used up 'in the'processl is considerably decreased witha' decrease, of course, in the cost of the process.

The amount of zinc which is placed in thedehalogenation columnwill usually be somewhat greater than the amount ordinarily employed in the zinc in the column we have found that con sumption of the'zinc by the process is considerably: iess' than in the priorart dehalogenation processes. hen an inert material is admixed with the zinc in the dehalogenation column, the

amount of zinc plus inert material will be the.

same as when the column is packed completely with the zinc.- In each case, the total amount of packing in the column should on the-average be from about twice to above five times the amount of zinc which is-=theoretically -necessary.

to completely dehalogenatethe halogenated ma;- terials' which are to be: deh'alo'genated' in the column. When an inert materiaL is= admired with the zinc, it is' necessary-of course, to have an amount of zinc'in the col'umn whichwill be sutfi'cient to accomplish the desired dehaloaen'aion. There is nodisadvantage in usin'ganexce'ss-amountof packing material in the column since in every case the acking material, after being washed toremove materials such as com pounds produced' by the reaction of theorganic acid with the zinc, e. g. zinc acetate, etc., may be reused in alater dehalogenation. Therefore, in most cases,v it is. preferred to use an excess amount of packing; in the column over what would theoretically be required to complete the dehalogenation.

The diameter and lengthof'the dehalogenation column may vary considerably and likewise the shape or the column may be' varied considerably. As a matter of convenience iti is preferred to employ. acylinder ofeiher'glassor some material such as steel and to pack such cylinder with the d'ehalogenat'ing. agent. The diameter or crosss-sectional area of, the column may be varied and ordinarily it will be governed by the size of the batch which is being passed through the column. Thus, inlaboratory operations, a column havinga diameter'of only llor ,2 inches is suitable whereas-in plant operation itis preferred to employ a column having a diameter of at least 5 or 6 inches. Likewise, the length of the column may vary andordinarily; it will depend somewhat upon the'diameter ofthe column inasmuchas'itis desirable to have the solution of the halogenated compound pass over a relatively large surface area of the-dehalogenating: agent. Thus if a column is employed which has a relatively large cross-sectional-area, the height of the column may be substantially less than the height of a column having only a relatively small cross-sectional area.

In passingthe solution of thehalogenated organic' compounds through the dehalogenation column, the solution is preferably passed through the column by gravity flow as a matter of convenience. Thus the solution may be placed in a suitable vessel located above the top ofthe column and the solution then slowly added tothe column at th top of the column. and allowed to flow rapidly through the column" and as it comes out the lower end of the column'it is collected in a suitable vessel. If desired, however, the solution may be added to the column at-the bottom thereof: and then forced upwardly by pressure flow and the solution of the dehalogenated organic compound collected from the top of the dehalogenating column. Also, if desired, the column maybe placed in ahorizontal'position or in any position between a horizontal and a vertical position and the solution ofithe halogenated compound then passed therethrough from either end of thecolumnr In such a case, particularly if the column is in 'a substantially horizontal position,

7 it may be desirable to provide meansfor slowly rotating the column so as to insure'proper contact of the halogenated organic compound with the dehalogenating-agent. In all cases the rate of fiow of thesolution through the columnshould be at ieast'approximately equal to the rate at which the solution will now through the column because ofithe force of gravity when: the column is-in a verticalposition-and the solutionisintroduced into the column at I the top: thereof;

By employing columns of considerablelcrosssectional area and relatively long length, it is possible to carry out a substantially continuous dehalogenation process. In most cases, however, it is preferred to run a fairly large amount of a solution of the compound to be dehalogenated through the column and then subject the dehalogenating agent in the column to a treatment which will remove therefrom materials which is at least 20 mesh in size and preferably zinc of about mesh in size is utilized; however, larger or smaller sizes of zinc may be used if desired. It is usually desirable to employ as an inert material some material which is of a size slightly larger than the size of the zinc in the column so that, if desired, the zinc may later be readily separated from th inert material by a simple screening operation. Thus in the preferred packing which w employ, We utilize 10 mesh zinc and 8 mesh silicon carbide. After a dehalogenation reaction has been carried out in the column, the packing material may be removed therefrom and the zinc recovered by a simple screening of the packing material. Thereafter, of course, the

recovered zinc may, if desired, be admixed again in the proper proportions with an inert packing material and used for another dehalogenation reaction. It is sometimes desirable to separate the zinc from the inert packing material following a dehalogenation reaction in order that the amount of zinc which was used up in the reaction may be determined and in order that if such zinc is to be reused it may be readmixed in the proper proportions with an inert packing material.

For a fuller understanding of the nature and objects of the invention, reference may be had to the following examples which are given merely as further illustrations of the invention and are not to be construed in a limiting sense.

Example I A dehalogenation column was prepared by packing a glass tube, which was 90 cm. in length Two liters of an acetic acid-ethylen dichloride solution of the product resulting from the chromic acid oxidation of cholesteryl acetate dibromide were placed in the dropping funnel. The funnel was then opened suiiiciently so that it required 4 hours for the two liters of solution to enter the column. At the same time that this dehalogenation was being carried out in the column,

= another two liter sample of the same solvent solution of the product resulting from the chromic acid oxidation of cholesteryl acetate dibromide was subjected to dehalogenation in accordance with th prior art processes wherein the two liters of the solution were placed in a large flask and stirred for 2 hours at 45-50 C. with 33 gms.

- of zinc dust.

Both solutions after the debromination was complete were poured into water and the aqueous mixtures obtained were extracted with ethylene dichloride. The ethylene dichloride solutions which were obtained were subjected to distillation and the residues remaining after such distillations were dissolved in methanol, chilled to crystallize any cholesteryl acetate therein and then filtered to remove such crystallized cholesteryl actate. Each methanol solution was then treated with semicarbazide hydrochloride and pyridine to precipitate the semicarbazone of dehydroisoandrosterone acetate. The sample which was dehalogenated in accordance with the prior art processes gave 1.92 gms. of semicarbazone whereas the sample which was dehalogenated by the process of the present invention gave a yield of 2.21 gms. of semicarbazone which was a 15.1% higher yield than the yield obtained by the prior art processes.

Example II A dehalogenation column was prepared similarly as in Example I except that in this case the packing used consisted of 800 gms. of 10 mesh zinc and 800 gms. of 8 mesh silicon carbide. The glass tube which was used for the column had a length of 98 cms. and a diameter of 1.0 cms. 8.3% liters of acetic acid-ethylene dichloride solution of the product resulting from the chromic acid oxidation of cholesteryl acetate dibromide were introduced into this column over a period of 6 hours and at the same time a 9 liter sample of the same solution of the oxidation product was debrominated by the prior art process explained in Example I. The dehalogenated material in each case was worked up in the same manner as in Example I giving a yield of 11.91 gins. of semicarbazone from the process of the invention and a yield of 9.48 gms. of semicarbazone from the prior art process (the latter figure has been adjusted for the difference in starting volume). Thus there was a 25.6% greater yield with the process of the invention as compared to the yield of the prior art process.

Example III Similar comparative runs were made in this example as in Example II using a column the same as that in Example II, but using a different batch of oxidation product. In this case the process of the invention gave a yield which was 31.5% higher than the yield of the prior art process.

Example IV 8.5 liters of an acetic acid-ethylene dichloride solution of the product resulting from the chromic acid oxidation of cholesteryl acetate dibromide was diluted with 20 liters of water and then extracted five successive times with ethylene dichloride using 2 liter, 1 liter and then 3 diiferent 500 ml. portions of ethylene dichloride. The combined ethylene dichloride extracts were concentrated to 2.84 liters by distillation under reduced pressure and in the presence of 50 gms. of potassium acetate. One liter of acetic acid was admixed with the 2.84 liters of the ethylene dichloride solution and the resulting solution then passed through a glass column 84 cms. in length and 2.5 cms. in diameter which was packed with 300 gms. of 10 mesh zinc and 300 gms. of 8 mesh silicon carbide. The rate of flow of the solution into the column was adjusted so that a period of 6 hours was required to introduce all of the solution into the column.

At .the *same atime an :equal sized :aliquot of'i'the same Oxidation .product was debrominated in accordance with the :prior .art process. The process of the present inventiongave a yield of 11:43 .gms. -'of :semicarbazone whereas the prior art process .gave aryield of 9.82'gms. Thus the process of the {present invention gave a 16.4% higher Tfiild than thexprocess .of the prior art.

Example JV nnother'dehalogenation was carried out using the column employed in Example I with the exception that in this case the'columnwas-packed with 113 gms. of Ill-mesh zinc mixed with Fenske (glass) packing'in alternate zones about 30 mm. deep. The rate of introduction of the solution into the column was 1 hour-and 25 minutes for 2 liters of the acid solution of the oxidized halogenated product. At the same time that this dehalogenation was being carried out, an aliquot of the same solution Was being dehalogenated by the prior art process. In this case the process of the present invention gave a yield of 1.54 gms. of semicarbazone whereas the prior art process gave a yield of only 1.41 gms. Thus the process of the invention gave a yield which was 9.2% higher than the yield obtained with the prior art process.

It is evident from the above description and examples that the process of the present inbelieved in the prior art to be necessary to heat the reaction mixture and to employ means of continuously mixing the zinc with the material to be dehalogenated, it is obvious that the apparatus and operating space required in the prior art take up more space and involve more expense than is the case in the process of the present invention. Furthermore, the process of the invention is much simpler than the processes of the prior art since it may be carried out by merely allowing the acid solution of the material which is to be dehalogenated to flow through a column packed with zinc. As has been pointed out above, it is possible to cut down considerably on the amount of zinc which is required by admixing with the zinc a relatively large amount of inert material such as silicon carbide, glass or other suitable inert material. Thus it is evident that the process of our invention, although it may seem to 'be a rather simple change from the prior art teachings, is actually a great ad- Vance in the art of dehalogenating oxidized halogenated sterol compounds. Although the time required to dehalogenate a large quantity of a halogenated compound is just as great when our new process is used as when the prior art methods are employed, the length of time during which each molecule of halogenated compound and dehalogen-ated compound produced therefrom is in contact with a dehalogenating agent is far less when our new process is used than when the prior art methods are employed. This much shorter time of contact of the individual molecules with the dehalogenating agent is possibly one of the reasons why our process gives so much higher yields than the prior art processes since a shorter contact time undoubtedly reduces the amount of undesirable side reactions which occur.

Having described our invention what we claim as new and desire to secureby Letters Patent is:

3.1. In a process. for dehalogenating' a halogenated sterol compound which has been subjected :to oxidation wherein the dehalogenation of the oxidized halogenated sterol compound is accomplished by reacting the oxidized halogenatedsterol'compound withzincsin the presence of a short "chain fatty acid, the improvement which comprises slowly introducing an acid solution comprising .the oxidized halogenated sterol compound and ashort chain fatty acid into a column packed :with .a packing material selected from the group consisting of zinc and mixtures oflzin'c and inertmateriallin which the inert materialmaycompriseup to aboutr% of the mixture, passing theacid solution which has been introduced into othe .column through the column at a rate which is at least approximately equal:to the rate at which the solution will flow through the column because of the force of gravity when the column is in a vertical position and the solution is introduced into the column at the top thereof, and recovering the desired deh-alogenated sterol compound from the acid solution after the acid solution has passed through the packed column.

2. The process of claim 1 wherein the acid solution of the oxidized halogenated sterol compound contains up to about five parts of an inert organic fat solvent for each two parts of short chain fatty acid.

3. The process of claim 1 wherein the short chain fatty acid which is employed is acetic acid.

4. The process of claim 1 wherein the packing material in the column is a mixture of zinc and silicon carbide.

5. The process of claim 1 wherein the acid solution of the oxidized halogenated sterol compound contains up to about five parts of ethylene dichloride for each two parts of short chain fatty acid.

6. The process of claim 1 wherein the acid solution of the oxidized halogenated sterol compound contains un to about five parts of ethylene dichloride for each two parts of short chain fatty acid and wherein the short chain fatty acid is acetic acid.

7. The process of claim 1 wherein the acid solution of the oxidized halogenated sterol compound contains up to about five parts of ethylene dichloride for each two parts of short chain fatty acid, wherein the short chain fatty acid is acetic acid, and wherein the packing material in the column is a mixture of zinc and silicon carbide.

8. In a process for dehalogenating oxidized halogenated derivatives of cholesterol obtained by the chromic acid oxidation of a halogenated cholesterol compound wherein the dehalogenation is accomplished by reacting the oxidized halogenated compounds with zinc in the presence of a short chain fatty acid, the improvement which comprises slowly introducing an acid solution comprising the oxidized halogenated derivative and a short chain fatty acid into a column packed with a packing material selected from the group consisting of zinc and mixtures of zinc and inert material in which the inert material may comprise up to about 50% of the mixture, passing the acid solution which has been introduced into the column through the column at a rate which is at least approximately equal to the rate at which the solution will flow through the column because of the force of gravity when the column is in a vertical position and the solution is introduced into the column at the top thereof,

, and recovering the desired dehalogenated sterol compound from the acid solution after the acid solution has passed through the packed column.

9. The process of claim 8 wherein the packing material in the column is a mixture of zinc and silicon carbide.

10. The process of claim 8 wherein the short chain fatty acid which is employed is acetic acid.

11. The process of claim 8 wherein the acid solution of the oxidized halogenated sterol compound contains up to about five parts of an inert organic fat solvent for each two parts of short chain fatty acid.

12. The process of claim 8 wherein the acid solution of the oxidized halogenated sterol compound contains up to about five parts of ethylene dichloride for each two parts of short chain fatty acid.

12 13. The process of claim 8 wherein the acid solution of the oxidized halogenated sterol compound contains up to about five parts of ethylene dichloride for each two parts of short chain fatty acid and wherein the packing material in the column is a mixture of zinc and silicon carbide; 14. The process of claim 8 wherein the acid solution of the oxidized halogenated sterol compound contains up to about five parts of ethylene dichloride for each two parts of short chain fatty acid, wherein the short chain fatty acid is acetic acid, and wherein the packing material in the column is a mixture of zinc and silicon carbide.

ROLAND KAPP. RICHARD GRIFFITH.

No references cited.

Claims (1)

1. IN A PROCESS FOR DEHALOGENATING A HALOGENATED STEROL COMPOUND WHICH HAS BEEN SUBJECTED TO OXIDATION WHEREIN THE DEHALOGENATION OF THE OXIDIZED HALOGENATED STEROL COMPOUND IS ACCOMPLISHED BY REACTING THE OXIDIZED HALOGENATED STEROL COMPOUND WITH ZINC IN THE PRESENCE OF A SHORT CLAIM FATTY ACID, THE IMPROVEMENT WHICH COMPRISES SLOWLY INTRODUCING AN ACID SOLUTION COMPRISING THE OXIDIZED HALOGENATED STEROL COMPOUND AND A SHORT CHAIN FATTY ACID INTO A COLUMN PACKED WITH A PACKING MATERIAL SELECTED FROM THE GROUP CONSISTING OF ZINC AND MIXTURES OF ZINC AND INERT MATERIAL IN WHICH THE INERT MATERIAL MA COMPRISE UP TO ABOUT 50% OF THE MIXTURE, PASSING THE ACID SOLUTION WHICH HAS BEEN INTRODUCED INTO THE COLUMN THROUGH THE COLUMN AT A RATE WHICH IS AT LEAST APPROXIMATELY EQUAL TO THE RATE AT WHICH THE SOLUTION WILL FLOW THROUGH THE COLUMN BECAUSE OF THE FORCE OF GRAVITY WHEN THE COLUMN IS IN A VERTICAL POSITION AND THE SOLUTION IS INTRODUCED INTO THE COLUMN AT THE TOP THEREOF, AND RECOVERING THE DESIRED DEHALOGENATED STEROL COMPOUND FROM THE ACID SOLUTION AFTER THE ACID SOLUTION HAS PASSED THROUGH THE PACKED COLUMN.