US3047636A - Halogenated organic compounds - Google Patents

Description

United States Patent 3,047,636 HALOGENATED ORGANIC COMPOUNDS Murray Hauptschein, Glenside, andMilton Braid, Philadelphia, Pa., assignors to Pennsalt Chemicals Corporation, Philadelphia, Pa., a corporation of Pennsylvania No Drawing. Filed Jan. 11, 1960, Ser. No. 1,440 4 Claims. (Cl. 260-653) This invention relates to the preparation of the iodide 1,1,2-trichloro-2,2,-difluoro-l-iodoethane.

In accordance with the'invention it has been found that when iodine monochloride (ICl) is reacted with the olefin CF CCI products of the general formula C F Cl I are produced.

It has been found that these products consist, under normally chosen reaction conditions, of a mixture of isomers having substantially the same boiling point, namely the isomer 1,1,2-trichloro-2,2 difluoro 1 iodoethane, CF ClCCl I and the isomer 2,2,2-trichloro-1,l-difluoro-1- iodoethane, CCl CF I. As 'will be pointed out more in detail hereafter, the isomer CF ClCCl I is an excellent telogen or chain transfer agent for carrying out telomer ization reactions involving reactive olefins such as CF =CFCl and CF =CF while the isomer CCl CF I is, relative to the former isomer, a very poor chain transfer agent for this purpose, 'It has also been found that under normally chosen reaction conditions a substantial propor tion of iodide or olefin is chlorinated to the compound CF ClCCl instead of being converted to the desired iodide.

In accordance with the invention it has been found that the isomer CF ClCCl I may be prepared, while producing little or substantially none of the undesired isomer CCl CF I by reacting iodine monochloride with the olefin CF =CCl at low temperatures, namely, temperatures ranging from -20 C. to +15 C. and preferably from -10 C. to +10 C. At these temperatures less than 5%, and at the preferred temperatures less than 0.5% of the isomer CCl3CF I appears in'the reaction products. At temperatures higher than +1 5 C. on the other hand, the amount of the undesired isomer CCl CF I formed progressively increases. It has also been found at these low temperatures little or substantially none of the chlorinated by-product CF ClCCl is produced while at higher temperatures the amount of this by-product progressively increases.

To prevent the formation of the isomer CCl CF I it has also been found desirable to avoid the presence of iron in the reaction mixture in a form which is chemically attacked by the reaction mixture or products. Apparently, iron in this form, or more probably iron compounds formed by the attack of the reaction mixture'upon the iron, acts as a catalyst for the formation of the undesired isomer CCI CF I. The presence of iron in a form that is not chemically attacked, such as the use of iron-containing alloy equipment is generally not detrimental. Thus, for example, a Monel metal autoclave, consisting predominantly of an alloy of nickel and copper and containing, e.g. 1 to 7% iron alloyed therewith may be employed.

According to the preferred method of carrying out the reaction, the olefin, which is a liquid'at reaction temperatures (boiling point 19 C.) is cooled to the reaction temperature (e.g. 0 C.) an ice or an ice-brine bath being suitable for this purpose. Iodine monochloride (preferably as a liquid) is then added slowly to the liquid olefin while vigorously agitating the reaction mixture. Preferably agitation is continued for a period of e.g. 1 to 2 hours after addition of the iodine monochloride is completed.

In order to insure complete utilization of the iodine monochloride, and to avoid having to remove excess 3,047,636 Patented July 31, 1962 iodine monochloride from the reaction mixture, the olefin is preferably used in stoichiometric excess in the reaction mixture. Molar ratios of olefinzICl of from 3:1 to 1:1 and preferably from 1.321 to 1.11 1 will generally be found satisfactory. Following the reaction, unreacted olefin may be removed from the reaction mixture, for ex-. ample by refluxing under reduced pressure.

The reaction is most conveniently carried out at at mospheric pressure, although pressure is not critical and elevated pressures may be employed if desired.

The reaction time is not critical. Depending somewhat upon the reaction temperature, reaction periods of from 5 hours to 1 minute and more usually from 2 hours to onehalf hour are satisfactory.

In the event all of the iodine monochloride is not reacted, the unreacted ICl may be removed by washing with water, preferably by pouring the reaction mixture over crushed ice. The iodine monochloride decomposes into products soluble in the water layer, as well as solid iodine, which then may be separated from the product iodide. The following examples illustrate the preparation of the iodide CF ClCCl I and the effect of temperature upon the formation of the undesired isomer CCl CF I and the undesired chlorination product CF ClCCl Example 1 166 grams (1.25 moles) of CF =CCl is introduced into a glass flask cooled by means of an ice-brine bath to -10 C. 162 grams (1 mole) of iodine monochloride is added to the liquid olefin drop by drop whilevigorously stirring over a period of one-half hour while maintaining the reaction mixture at 10 C. Stirring is continued for an additional two hours after which 35 grams of unreacted olefin is removed from the cold reaction mixture under reduced pressure.

The remaining product consists of 292 grams made up of 290 grams of the iodide CF ClCCl I and 2 grams of CF CICCI The product is free from detectable traces of the undesired isomer CC1 CF I.

The iodide CF ClCCl I is a solid at room temperature, having a boiling pointof C. at 75 mm. Hg and a melting point of 35 to 37 C. The ultraviolent absorption maximum for CF ClCCl I in isooctane is at 302 III/L.

Characteristic absorption bands in the infrared spectrum of CF -ClCCl I (vapor) are at 8.58, 9.8, 11.7, 11.8 (shoulder), 11.9 (shoulder), 13.0, and 14.5 microns. Analysis of this compound is as follows:

Calculated for C Cl F I: C, 8.1, Cl, 36.0. Found: C,

Example 2 Example 3 To 300 grams (2.25 moles) of OF =CCI in a glass flask cooled to +15 C. there is added drop by drop over a period of two hours 292. 5 grams (1. 8 moles) of iodine monochloride while stirring. Stirring is continued for another 2 /2 hours after which the crude product is worked up to yield 9.2 weight percent of unreacted CF =CCl 3.0 weight percent of CF clCCl and 87.8 weight percent of C F CI I. The iodide product C F Cl I consists of 3 98% of the desired isomer CF ClCCl I desired isomer CCl CF I.

Example 4 and 2% of the un- To 90 grams (0.55 mole) of iodine monochloride there is added with stirring 80 grams (0.602 mole) of CF CCI in a glass flask equipped with a reflux condenser for maintaining the reaction mixture at a temperature of about C. There is obtained 150 grams of crude product. This product is analyzed by vapor-liquid partition chromatography and shown to consist of 72 mole percent (79 Weight percent) of isomeric iodides C F Cl I and 28 mole percent (21 weight percent) of byproduct CF ClCCl The isomeric iodides are analyzed and shown to consist of a mixture of 1 1% of the undesired isomer CCl CF I and 89% of the desired isomer OF CICCI I. Using a Perkin Elmer B chromatographic column 2 meters in length and operating at 100 C. under a pressure of helium of lbs/in. gage, the respective elution times for air, CCl CF I and CFgClCClgI are 0.55 minute, 43.5 minutes and 52 minutes respectively. The isomer CCl CF I has a boiling point of 74 C. at 75 mm. Hg. The ultraviolet absorption maximum for CCl CF I in isooctane is at 275 mg. The respective structures of the two isomers is confirmed by their ultraviolet absorption maxima.

As may be seen from the results of the foregoing example, when the reaction was carried out at approximately room temperature, the isomeric content of was 11% and 28 mole percent of the product consisted of by-product CF ClCCl At higher reaction temperatures, the content of this undesired isomer and of the undesired lay-product CF CICCI in the reaction product progressively increases until these products may become together the major products of the reaction.

As pointed out previously, the isomer CF ClCCl I is an excellent chain transfer agent or telogen in telomerization reactions involving olefins such as CF =CFCl and CF CF When this isomer is used as a telogen with these olefins, it is possible to control the molecular weight or chain length of the telomers so as to obtain high yields of desired narrow ranges of molecular weights merely by selection of the olefinztelogen iodide molar ratio, the number of olefin units in the telomer chain closely approximating the olefinziodide ratio in the reaction mixture. Such telomerization reactions, employing the isomer CF ClCCl I are described in detail in the co-pending application Serial No. 756,491, filed August 21, 195 8, and now abandoned, of Murray Hauptschein et al. entitled Halogenated Organic Compounds.

In contrast, the isomer CCl CF I is a relatively poor chain transfer agent in such telomerization reactions. For this isomer, considerably higher temperatures are required to obtain any telomerization at all, and the telomers formed tend to vary over wide ranges of molecular weights, from low molecular Weight liquids of comparatively little utility to mainly high molecular weight solids likewise of limited utility, rather than the desired high yields of intermediate molecular weight products of an oily character. In addition, such telomers that are formed with the isomer CCl CF I, e.g. telomers of the formula CCl CF (CF CFCl) I have the disadvantage that the telomer terminates in a CCl end groupwhich has considerably lower chemical and thermal stability than a CF Cl end group produced by the isomer CF CICCI I, and are far less useful for transformation to surface-active agents.

This application is a continuation-in-part of copending application Serial No. 762,708, filed September 23, 1958, and now abandoned.

We claim:

1. A method for preparing the iodide CF ClCCl I comprising the step of reacting CF =CCl with iodine monochloride at a temperature of from 20 C. to +15 C.

2. A method in accordance with claim 1 in which said reaction is carried out at a temperature of from 10 C. to +10 C.

3. A method for preparing the iodide OF ClCCl I comprising the step of reacting CF CCI with iodine monochloride at a temperature of -20 C. to +15 C. in the References Cited in the file of this patent Migrdichian: Organic Synthesis, vol. 2, page 856 (1957).

Claims (1)

1. A METHOD FOR PREPARING THE IODIDE CF2CICCI2I COMPRISING THE STEPS OF REACTING CF2=CCL2 WITH IODINE MONOCHLORIDE AT A TEMPERATURE OF FROM -20*C. TO +15*C.