US2492941A - Process for chlorinating chlorpropane - Google Patents

Description

atented Dec. 27, 1949 UNITED STAT PROCESS FOR CHLORINATING CHLORPROPANE Hooker Electrochemical Company,

Niagara Falls, N. Y., a corporation of New York No Drawing. Application December 8, 1944, Serial No. 567,314

3 Claims. (01. 204-163) Our invention relates more particularly to lromotion of organic halogen substitution reacions, especially when it is desired to carry the eaction further than it will readily go under vrdinary-conditions. An example of such a relction is afiorded by photochemical chlorination If paramnic hydrocarbons to complete replacement of the hydrogen by chlorine. It is known hat such reactions are retarded or inhibited in )resence of oxygen or the resulting oxygenation )roducts. One of the objects of the invention is promote the speed and completeness of the 'eaction and carry it further than would othervise be practicable under such conditions.

The partial chlorination of hydrocarbons of all :inds is comparatively easy. The complete chlo- -ination of hydrocarbons is much more difficult. Methane and ethane are about the only hydro- :arbons that have hitherto been fully chlorinated in a commercial scale.

We will describe our process with particular reference to production of octachlorpropane. This may be produced without great difiiculty by ihlorination of hexachlorpropylene. However, cexachlorpropylene is a valuable product in itself and it is one of the objects of the present invention to product octachlorpropane directly from propane.

Propane is derived from natural gas and may be chlorinated, starting in vapor phase, to produce mixtures up to the heptachlor, which are liquid at ordinary temperatures. These mixtures may then be further chlorinated to octachlorpropane in liquid phase. This has been done, on a small scale, by various processes, all of which are unsatisfactory as to cost or yield or both. One of the objects of the present invention is to produce octachlorpropane by a practicable process, suitable for operation on a commercial scale, so as to render the produce available to the arts.

One way in which octachlorpropane has hitherto been produced on a small scale is by first chlorinating to the heptachlor and then dehydrochlorinating by means of caustic soda to hexachlorpropylene which, being unsaturated, may be chlorinated without great diiiiculty to octachlor Mixtures of chlorpropanes have been further chlorinated in liquid phase to a mixed product containing a minor proportion of octachlorpropane by the use of a liquid chlorinating agent,

such as iodine trichloride, antimony pentachlo- "ride, etc., or by the use of liquid chlorine under high pressures, in both cases at about 200 C. At

this temperature there is much-splitting of the molecule to carbon tetrachloride and hexachlorethane. These mixtures have also been chlorin-- ated with gaseous chlorine at atmospheric pressure by the aid of very powerful actinic light, likewise at about 200 C. As before, there is much splitting of the molecule; alsothe intensity of the 1 required light limits the size of the chlorinationunits, and the time cycle is excessive.

We have now succeeded in chlorinating mix tures-of chlorpropanes, having a specific gravity of 1.70 to 1.76, corresponding to a mixture of pentachlorto heptachlorpropane, by means of gaseous chlorine, and with the aid of actinic light of moderate intensity (1,200 watts for a 500 gallon reactor) at a moderate temperature and pressure to 150 C. andlO to lbs. per sq. in.

(respectively), with an almost quantitative yield of octachlorpropane.

prior to further chlorination thereof, with a basic substance, such as the alkali metal'and alkaline earth hydroxides and alkali metal carbonates, in such small quantities and under such conditions as to cause no appreciable dehydrochlorination of the material or other modification of its molecular structure. This treatment is effected by agitating the liquid chlorpropane mixture with a small quantity of the alkali, amounting to one or two per cent by weight, at 35 to 90 0., for from 30 to 60 minutes, and then filtering out the solids from the liquid material," and thus removing any solid or colloidal suspended contaminants. Without this treatment the further chlorination of the chlorpropane mixture, under the conditions as to temperature and pressure indicated above, is'impracticable, if not impossible.

After this treatment, however, the chlorination: proceeds rapidly and smoothly to substantial completion, with an almost" quantitative yield,

as above stated.

The product obtained by our process as above crystalline product,

described analyzes within one per cent or less of the chlorine content corresponding to octachlor propane made by the process of the prior art. This is within the limits of error of the best known methods for determination of chlorine in organic compounds.

Octachlorpropane, such as may be produced by chlorination of hexachlorpropylene, is a white crystalline material melting at 150 C. and theoretically containing 88.7 per cent chlorine. It may be readily ground to a powder. Our product contains 88+ per cent chlorine by analysis and melts at 120 to 155 C. It has a tough waxy consistency and cannot be ground. It gives off only 0.02 to 0.04 per cent of its chlorine when maintained at 140 C. for 16 hours. This is an evidence of a high degree of stability as compared with chlorinated hydrocarbons in general,

some of which would give off 30 per cent of their chlorine under similar conditions.

Why our octachlorpropane product should have physical characteristics different from those of the prior art product, is not at present known. At any rate, the diiferent physical properties of our product, as compared with those of the give it greatly enhanced value. For example, it is firmly adherent to smooth surfaces. It is compatible with lubricating oils and is itself an excellent lubricant for such surfaces as those of plug cocks and bearingj's exposed to highly corrosive chemicals, such as chlorine, HCI, H2804, etc. It is also an excellent plastici zer for natural and synthetic resins, formingtherewith a great variety of compositions suitable for impregnation and coating, for the purpose of fireproofing and weather prooiing. 7

Our octachlorpiopane product also forms with other chlorinated hydrocarbons a whole series of compositions having useful properties. .In particular it forms with hexachloretha'ne a series of compositions which are unique in that, although fully chlorinated, they are nevertheless of a tough waxy consistency, being in this respect entirely unlike compositions produced by blending hexa'chlorethanei with pure crystalline octachlorpropane.

Example I 1150 lbs. of'chloipropane mixture having a spe cific gravity of 1.73 corresponding to a mixture consistingm'ostly of pentachl'or. to heptachlo'rpro pane", were agitated withlbs. of oa(oH)2 at 90 for one hour and the material passed through a filter press. The filtered material Weighed 1110 lbs. This Was chlorinated under actlnic light as follows:

The product was blown for 15 minutes with CO2 to remove dissolved H01 and C12. When cast and cooled into a slab and dropped onto a hard surface it emitted a metallic clink. It could not be ground. It was substantially colorless" andof a waxy consistency, analyzed 88+ per cent chlorine. and had a first crystal point of 143 0., a

, first example.

The product of Example I was blended with liexachlorethane in various proportions ranging from 20 to 200 per cent of its weight of the latter, and" the cloud points determined. It was found that the mixture containing 20 per cent of hexachlorethane had a cloud point of about 108 GA, which was thelowest cloud point obtained. This composition was transparent, tough and extremely flexible. When melted and poured on "glass it could not be chipped or scraped off or otherwise removed without the aid of heat or a solvent- It proved tobe inert to a ueous HF glass etching soiution. When rolled out a sheet it was found to have considerable tensile strength and elasticity, and when out into strips these could be twisted and tied into knots.

, Example III Two identical portions air blown to saturation with oxygen. One was given the alkali treatment, as in Example I'. The other was not treated. rinated to octachlorpropane, likewise as in the The alkali treated portion re quired zc'ncurs' aia'd 1.022'lbs.

lbs. of chlorine per pound of product. The second required '75 hours and consumed 1.545 lbs. of chlorine per pound of product. This shows that oxygen in the chlorine has the same inhibiting effect as oxygen in the hydrocarbon.

Since the reaction is exothermic, the temper:

ature of the reaction mixture a given stage of the reaction, under given conditions as to radiation" of heat, etc, is a function of the rate of re action. The effect of the alkali treatment upon the rate and completeness of absorption of the chlorine, can therefore be likewise demonstrated by noting the temperature of the reaction inixture as the reaction proceeds.

Example V 500 c. c. of dichlor'ethane (ethylene dichloride) were air blown for 15 minutes to saturate the lid} uid with oxygen. The sample was then divided into two equal portions. one part was given a treatment with a 10' per centsoliition of NaOH 'for' 30 minutes and dried. Each portion was of chlorpropane, having the ame specific gravity as in Example I, were Both were then" ch10 H chlorine'per pound. of product. The other required 55 hours and 1.511 lbs. chlorine per pound of product. This";

nlaced in a 250 c. c. flask and the two flasks placed n a constant temperature bath maintained at $0 C. Both portions were chlorinated at atnospheric pressure by gaseous chlorine introluced at the same rate; namely, 280 c. caper ninute under the same conditions as to actinic ight, and the change in temperature with lapse )f time noted. 7

The results were as follows:

Temperature Time Minutes Untreated Treated Portion Portion MOI The results show that at 7 minutes both portions were at the same temperature. After 9 minutes the portion that had been given the alkali treatment had forged ahead. After 15 minutes, the temperature of the untreated portion was falling. This is normal; but at the same time the temperature or the treated portion was rising. This is a wholly unpredictable result.

Example VI The experiment of Example V was repeated with a chlorheptane mixture having a specific gravity of 1.527, corresponding to a chlorine content of 70.5 per cent. After 23 minutes this showed the same phenomena, namely a falling temperature in the case of the portion that had not had the alkali treatment and an anomalous rising temperature in the case of the treated sample.

Example VII holds for long chain as well as for short chain paraffinic hydrocarbons; but also that it is not due merely to neutralization of HCl.

Example VIII The experiment of Example V was repeated with isopropyl adipate. The same anomalous and unpredictable result was obtained. That is to say, after 9 minutes the untreated portion was at 62 C. and the treated portion at 65 C. This shows that the alkali treatment promotes chlorination even when there is oxygen in the molecule. In this case, the reaction was found to be chiefly a substitution of chlorine for hydrogen in the isopropyl group.

Example IX The experiment of Example V was repeated with isopropyl benzoate. The results were the same as before. That is to say, after 6 minutes the untreatedportion showed a temperature of 59 C. and the treated'portion-a temperatureof 62 C. ,-proving that the beneficial efiect of the alkali treatment is not limitedto parafflnic compounds. As in Example VIII, the reaction was I principally a: substitution of chlorine for hydrogen in the alkyl-group.

While we have illustrated our process by specific example, we do not wish to be limited thereto, as our-process is evidently applicable to halogenation of organic materials in general, the halogenation of which is'retarded in presence of oxygen other than oxygen that may be in the molecules of the material itself, and the molecular structure of which is not modified by the treatment preparatory to halogenation. Neither do we wish to be limited to photochemical halogenation, as our process is applicable to analogousheat or infra-red activated or chain.

mechanism halogenation of organic materials within the above defined category which are susceptible of halogenation under such conditions. Likewise, we do not wish to be limited to the alkalis specifically mentioned or used in the ex ample, as any basic reacting substance is more or less effective in our process, when the conditions of the reaction, i. e., as to the reactivity and concentration of the basic reacting substance, temperature at which the treatment is carried out, time of treatment, etc., are such that there is little or no dechlorination, dehydrochlorination or other modification of the molecular structure of the material.

We claim as our invention:

1. The process for chlorination by substitution of chlorpropane, by means of gaseous chlorine, when one of the reagents contains free oxygen, which comprises contacting the liquid organic material with 1 to 2 per cent of its weight of a material of the group consisting of the alkali metal and alkaline earth hydroxides and alkali metal carbonates, for at least 30 minutes; removin the alkaline material and any suspended solids from the organic material; and passing gaseous chlorine into the organic material, at

to 150 C. and under a pressure of 10 to pounds per square inch gauge, under actinic light effective in catalyzing the reaction, until the reaction has gone as far as practicable.

2. The process for chlorination by substitution of chlorpropane mixtures having a specific gravity of 1.70 to 1.76, by means of gaseous chlorine, when one of the reagents contains free oxygen, to produce octachlorpropane, which comprises contacting the liquid organic material with 1 to 2 per cent or its weight of a material of the group consisting of the alkali metal and alkaline earth hydroxides and alkali metal carbonates, for at least 30 minutes; removing the alkaline material and any suspended solids from the organic material; and passing gaseous chlorine into the organic material, at 90 to C. and under pressure of 10 to 100 pounds per square inch gauge, under actinic light effective in catalyzing the reaction until the reaction has gone as far as practicable.

3. The process for chlorination by substitution of chlorpropane mixtures having a specific gravity of 1.70 to 1.76, by means of gaseous chlorine, when one of the reagents contains free oxygen, to produce octachlorpropane, which comprises contacting the liquid organic material with 1 to 2 per cent of its weight of calcium hydroxide at 35 to 90 C. for 30 to 60 minutes;

emo izm: tho alkaline; mammal and amr'sius ponded sclid o item. the: o ani v maierial: a d pmina asaous: chlorine into the organic: mate-4.. rialiat 8,0? to: 150? Radar a, pressure-coi 2a to noundainer square. inch-gauge, under actinic: l ht etfe tive, in. catalyzin the reac ion: until. the reaction has gone aarfar. as; practicable, JAMES S. SQQNG-E; DAVID SzRQSENBER-Q.

N. JQHNSQN:

REFERENCES; CITED he w ng r rence are rco i th file of "patent:

V TATE FAWN-T3 7 Date 8 umber Name Bate 212 11 168 M rsh o-----=.--- Aug. 13, 19 0 2,296,614 Hearne Sept. 22, 1942.; 2,318,681 Gaylor May 11, 19%: 2,334,033 Riblett, Nov. 9, 19.43

Churchill et a1. Dec. 12, 194.;

' OTHER REFERENCES M Be t a Indus ria and En ine ring 1Q Chemistry, February 1941, pp. 176-181.

Stowart et aL, Journal American Chemical Society, October 1929, pp. 30854;.

Mailer, I organic and Theoretical Chemistry. vol. I' (1927), Pp, 369-370.

Hackh, Chemical Dictionary, 3d 1.914), p- .1,.-

edition