ALBERT L. HENNEAND JAMES B. HINKAMP
1194
Vol. 67
for all colloidal electrolytes tested, whether the fastest ion is the relatively slow sodium or the highly mobile hydrogen ion. It is as though the mobility of the colloid adjusted itself to that of the gegen ion. Reference to Fig. 4 shows a qualitative parallel between the observations made here and Brady’s observations. The steeper of the two straight lines, corresponding to the more mobile of two cations, intercepts the hyperbolas at a higher point, the point of intersection determining the contribution of the “hyperbolic” part to the total conductivity. If the “hyperbolic” part corresponds to conducting micelles, the latter automatically adjust their contribution to the mobility of the gegen ion as a necessary consequence of equation (1).
Thus colloidal electrolytes in the region under discussion behave as though the conductivity were due to two ionic species, the mobility-concentration product of one of which is increasing with the square root and that of the other as the threehalves power of the solute concentration. Our present knowledge of colloidal electrolytes does not permit an interpretation of these facts in terms of chemical equations consistent with all available data. Therefore, for the present, it is safer to regard this as purely formal analysis, which, however, must have a physical basis. Acknowledgment.-The author wishes to express his sincere thanks to Professor J. W. McBain for his valuable assistance and suggestions in the preparation of this manuscript.
TABLE 11 COMPARISON OF CALCULATED TRIEORRTICAL MAXIMUMAND OBSERVEDCONDUCTIVITY AT THE Cdm.(BRADY)
summary
-
andad.
Substance
Add./&
Lauryl sulfonic acid Cat01607 Potassium laurate
-
%ob.. Aom./&
0.390 .371 .507
0.317 .287 .389
a.b../aod.Aob./badod.
1.24 1.29 1.30
Since the specific conductivity, L,being based on a fixed volume of solution, directly reflects changes of concentration and mobility of the conducting species present in the solution, it is worth noting that from equation (1) one gets AC = lOOOL = AC’/r BC‘/r (5)
+
1. The equivalent conductivity of the majority of colloidal electrolytes, in the region of the conductivity minimum, has been shown to f d o w the law: A = A / d C 4- B where A and B are constants depending primarily upon anion and cation, respectively. 2. The minimum in the conductivity curve occurs at a concentration equal to A / B . 3. The two parts of the equivalent conductivity, A / G and B C C , are equal when the conductivity is at its minimum.
a,
STANFORD UNIVERSITY, CALIFORNIA RECEIVED MARCH 5, 1945
[CONTRIBUTION FROM THE DEPARTMENT OF CHEMISTRY AT THE OHIO STAT$ UNIVERSITY]
The Synthesis and Directed Chlorination of 2,2-Difluorobutane BY ALBERTL. HENNEAND The chlorination of CFaCH,CH8, CHsCFCHs, and CHaCFCICH&l is known to be strongly directed.‘ To determine how far and in what direction the effect of a CFn group would extend, CH~CFICH~CHI was synthesized and chlorinated. The difluoromethane was obtained by hydrofluorination of CHsCCH&!H~,3~3and also by the action of hydrogen fluoride upon CH@!1= CHCHa,’*‘ C H d C l C H a C H a and CHaCFClCHpCHs. S i n c e large amounts of reagents were handled, the experimental procedures were modified as follows, for the protection of the operator. A five-liter, three-necked steel cylinder was fitted with a copper Dry Ice reflux condenser, a stirrer, and a copper inlet tube reaching the bottom. A quantity of commercial 70% CHaCCl= (1) (a) Hennc and Whdey. THISJOURNAL, 64, 1157 (1942); (b) Hcnac and Renoll, i b i d . , 19, 2434 (1937); ( c ) Heme and Haeckl, ibid., 68, 2892 (1941). (2) (a) H e m e and Plueddemann, i b i d . , S6, 587 (1913); (b) Grosre and Linn, ibid., 64, 2289 (1942). (3) Henne and Plueddemann. ibid., 66, 1271 (1943). (4) Renoll, ibid.. 64, 1115 (1942).
JAMES
B. HINKAMP
CHCHo corresponding to 22 moles of the pure compound was placed in the cylinder, and a stream of hydrogen fluoride was led through it. The reaction started at once, and as soon as it was well under way a large ice-bath was placed around the vessel. The reaction was conducted as fast as the capacity of the reflux condenser would allow. The hydrogen chloride discharged from the top of the condenser was absorbed in water. After feeding about one hundred moles of hydrogen fluoride (slightly more than twice the amount needed) the reaction mixture was stirred for two hours at room temperature. The reflux condenser was replaced by a scrubber containing continuouslychanged hot water, attached to an ice-cooled receiver. The steel vessel was progressively heated to 90” to boil off the reaction products. After washing, drying and fractionally distillin the distillate gave 11.3 moles (1062 g. or 51.38 yield) of pure CH&!F2CH&Ha and about 8% of intermediate CH3CFClCHzCHs from which more difluoride was obtained by subjecting to a
July, 1045
THESYNTIIESIS AND DIRECTED CIILORINATION OF 2,2-DIPI,rloRORUT.~NE
1195
fluorine atoms was ascertained by perchlorination to the known CClSCF2CCl2CCls. CHzClCFzCHzCHa was obtained in 55% yield Chlorination from C H S C ~ C C ~ ~ C Hmade ~ C Hin ~ 65% yield by In sunlight, in the presence of water, CHaCF2- chlorine addition to dry C H d C l C H 2 C H 3 in the CHzCHs gave only two of the possible three mono- dark and in the presence of solid sodium bicarbonchlorides; two parts of CH,CF2CHClCHa and ate. CHjCFzCHzCHzCl was identified by the fact three parts of CHaCF2CH2CH2Cl were formed, but not even a trace of CH2C1CF2CH~CH3.The end that it differed from the preceding monochlorides. CHzClCF2CHClCHs was obtained in %yoyield CHs adjacent to the CF2 group proved immune to chlorination, while the CH2 adjacent to the CF2 from commercial CH2ClCC12CHClCH3,6together group and the CHSonce removed were affected in with 53% of CH2ClCClFCHClCH3and 7y0 of reproportion to the number of hydrogen atoms avail- covered tetrachloride. It was also obtained in able for chlorination, i. e., apparently a t random. 45% yield from CH2ClCFCICHClCH3in addition On further chlorination, CHsCF2CHClCHs gave to 2970 of recovered material. The place of the two parts of CHaCF2CC12CHs to one part of fluorine atoms was demonstrated by perchlorinaCH3CF2CHC1CH2C1, but no CH2C1CF2CHC1CH8. tion to the known CC13CF2CC12CC13. CHsCFzCHClCHzCl was obtained quantitaOn the other hand, C H S C F ~ C H ~ C Hgave ~ C ~only CH&FL!Hd2HC12 without evidence of either tively by chlorine addition to CH3CF2CH=CH2 CHaCF2CHC1CH2C1 or CH2C1CF2CH2CH2C1,and made in 75% yield by hydrogen chloride removal a continuation of the chlorination gave seven parts from CH~CFZCH~CH~CI. CHClzCFzCHzCHj was obtained in 40% yield, of CHsCF&H2CCla to one part of CHnCF2CHC1CHC12 and no CH2C1CF2CH2CHC12. These re- to ether with 14% of CHC12CFClCH2CHs and sults illustrate the extent to which the alpha 1 5 5 of unreacted tetrachloride, from CHC12CC12made in 51% yield by chlorine addition methyl group is protected against chlorine, and CH~CHS they confirm the strong tendency to accumulate to 1-butyne vapors diluted in methylene chloride the chlorine atoms on the same carbon atom, and in the presence of solid sodium bicarbonate. The position of the fluorine atoms was demonwhich had been noted in the propane series.' To complete the study, CH2ClCFaCHaCHt was strated by perchlorination to the known CC13CF2synthesized as indicated hereunder, and subjected CC12CCl3. CHzClCFzCHzCHzCl was identified by being a to chlorination. It failed to give any CHCtCFsCH2CH8,but gave four parts of CH2ClCbCHs- dichloride obtained from CH2ClCF2CH2CH3 and CH2Clto one part of CH2ClCFsCHClCHs. This by being different irom both CH2C1CF2CHClCHs result reinforced the observation that an end group and C H C ~ Z C F ~ C H ~ C H ~ . CHsCFzCHzCHC12 was identified by being a diadjacent to a CF2 group resists chlorination. The two dichlorides actually formed were not chloride formed from CHaCF2CH2CH2Cl and by found to be in proportion to the number of hydro- being different from both CH~CICF~CHZCH~CI gen atoms available on each carbon, as beta and CHsCF2CHC1CH2Cl. CHjCFzCHzCCl3 was obtained from CH3CF2chlorination appeared to be favored. Finally, chlorination was allowed to proceed to CH2CHC12 and was shown to have a CC13 group completion and yielded CCLCF2CCl2CCls b. p. by its easy fluorination to CHsCF2CH2CFs, a 270' with slow decomposition. To accomplish pentafluoride which was also obtained from this result, several weeks of exposure to brilliant CFsCH2CC12CH3.' CHjCFzCHClCHClz was identified by its forsunlight a t a temperature of about 60' were remation from both CHsCF2CHClCH2Cl and CHsquired. CF2CH2CHC12.
second treatment with hydrogen fluoride, or by adding to a subsequent operation.
-
Identifications
Most chlorofluorides were identilied by comparing their freezing point, boiling point, density and refractive index with those of synthetic samples obtained from the needed polychlorides by fluorination with hydrogen fluoride and mercuric oxide, using the procedures previously reported.' The remaming chlorofluorideswere then identified by a process of elimination, based on their difference from established compounds. CEjCFzCHClCHs was obtained in 35% yield from CH&!Cl2CHClCH3 (made by chlorine addition to CHSCC1=CHCH3)together with CH3CFClCHClCH3 in 31% yield. The place of the (5) (a) Hennc and Midgley, Tars JOURNAL, 68, 884 (1936); (b) Henne. ibid.. 60, 1569 (1938); (c) Henne and Flanagan. ibid., 66, 2362 (19431.
Reactivity Tests The chlorofluorides were treated with an alcoholic solution of silver nitrate to test the ease of replacement of the chlorine atoms. The procedure consisted in treating three to five drops of organic material with 1 ml. of a 5% alcoholic solution of silver nitrate, and boiling for five minutes. Both CHzClCFzCH2CHa and CHsCF2CHCICHs failed to give a precipitate, while CHaCF2CH2CH2C1 gave a faint turbidity. In contrast, this test gives a strong precipitate even at room temperature with CHd.2F2CH2CH2CH2CL8 (6) Research Chemicals, S.n Jose,California. (7) J. Hinkamp. Dissertation, The Ohio State University, 1943. (8) W. Zimmerrchied. The Ohio State University. unpublished data.
TABLE I PHYSICAL PROPERTIES AND ANALYSIS CHICFICHICHI CH&FiCHiCH&l CHtCtCFcCIIrCHi CHICFICHCICHI CWSCCIEHI CHCIICFSCH&HI CXICFSCHSCHCI~ CHICICPICHCICN~ CHICFICHCICH~C~ CHiCICFL!€I&&CI CHICFICHICCII CRCFICHCICHCI: CClrcF1cClrCCl1 CWCPCICHICHI CHICPICXDCFI CWCldXCHi
Freeing range F. p., “C. 0.04 -117.53 .01 - 70.OR .ni 78.96 01 w2,i
-
2 ,I .01
+ 43.6Ii
-54.39 - 60.00
I 8
-005
0.6
-
..
9
......
E. p., *C. 30.92 93.22 8’2.72 72 32 118.84 111.22 119.26
115.67 128.1
d% 0.9159 1.1552 1.1553 1.1269 I ,2893( a t I 3113 1.3138 1.3270 1.328 1.3662 1.4306
28.7
142.28
’29.5
139.15 146 .... 9 8 , 2 m m . 1.8890 07.0s 0.8882 #,I4 1.2686 70.58 0.9m
- 8.42 -110.00 - 85.01
.00 2 01 9
-117.3
.8
-105.8
n%
.UR
1.313 1 ,3709
MIo)
1.3685 1 ,3631 1.3752( a t 1 . 397R 1.4017 1 ,4025 1.404 1.4153 1.4245 i.4ai 1.5198 1.3782 1.2824 1.4240
Chlorine % Fluorine % ARr Calcd. Found Calcd. Found
20.33 0.93 26.21 .93 27.0 27.9 29 5fi 23.OR .88 27.0 27.7 25.16 . ~ i27.6 x . n 2 0 . 6 ~ SOo) an. 12 .96 43.5 43.2 23 .?I 29.99 .89 43.6 4 3 . A 30.19 99 4 3 . 6 43 R 23 3 1 29.93 RG 43.5 43.Ci 30.0 .BO 43.5 43.1 29,99 .89 41.5 43.6 35.11 1.02 53.9 54.2 . . . .. . . , . 59.15 0.87 25.55 1.11 32,l 32.3 17.19 20.07 1 IO I 25.01
29.72 29.89
23.01 22
so
(I
16.71
clr isomer
{
CHrCCl-CHCHi b e l 8 hOmU
CRsCiCQICHClCH I CHCtCCtrCHaCHi
2.0 .
.
- 46to -48
GI-
02.84 182 180
* Improves data of Heme, Reno11 and Leicester,
1.4190
25.02
1.426 1.491 1.426 1.490 THISJOURNAL, 61, 938
39.7 39.7
0.9139
The interpretation was made that the CFt group immobilizes the chlorine atoms in dpha position, represses the reactivity of the chlorine atoms it1 beta position, and is practically without effect on the chlorine atoms in gamma position. Dehydrohalogenation with boiling alcoholic potassium hydroxide does not take place a t all with CH&lCFzCHgC&, nor CHEFtCHCICHB. The reaction, however, occurs very easily with CHICFgCH&HtC1. This can be interpreted on the basis of the reactivity of the chlorine atoms, in the same fashion as the preceding test, Or else, if one considers that in dehydrohalogenation the controlling factor is the ability of a hydrogen to come off ris a proton, then it can be reasoned that in pulling electrons toward itself, the CFa group loosens the binding of the alpha hydrogens, or, in other words, enhances their ability to be given off as a proton.
Purification and Physical Constants Chemical purification was used only on such
(1939). * Improves the literature data.
The criterion of purity Was, in all cases, the shape of the freezing curve or melting curve, determined on samples of about 50 g. with a resistance thermometer reading to 0.O0lo. The method of operation and of extrapolation of the freezing point to perfect purity was that of t h e Bureau of Standards.lo The freezing range recorded in the tabie is that between incipient crystallization and inability further to stir the mass. The normal boiling points were taken in a modified Cottrell apparatusll with a resistance thermometer and an automatic monostat to regulate the pressure a t 760 mm. The densities were taken with a Sprengel type pycnometer of 5-ml. capacity. Low boiling materials were measured in sealed pycnometers of the same capacity. The refractive indices were measured with an Abbe refractometer. The molecular refraction was calculated by the Lorenz-Lorentz formula. Subtracting from the experimental valueS the customary increments for carbon (2.418), hydrogen (l.lO0), chlorine (5.967) and double bond (1.733) gave the listed value for A R F , the atomic refraction of fluorine. The analyses were performed on the micro scale by decomposition with heated potassium‘ ’ or with sodium peroxide in a Monel bomb.I3
derivatives which proved to be contaminated by olefinic impurities, because the boiling points of compounds of the C R R ’ 4 R ” R ” ’ and CRR‘HCR”R”’F types we frequently very close together. A treatment with bromine or chlorine in sunlight was effective in these cases. This treatment eliminates the olefins, but also halogenates summary some material by substitution, hence causes CHKFsCHtCH, was synthesized by interaction appreciable losses when not well oontxolled. of dry hydrogen fluoride with commercial CH3Physical purification was accomplished by re- CCl=IcHCHI. Its chlorination gave only CH3peated distillation through an &batie column CF&HCICH*(A) and CH&F&H,CH&l(B). On one meter long and 15 mm. in diameter,packed (lo) Ma&, O a m r and Rosrini, J . RIse4tCh Noll. Bur. Standards with glass helices, and fitted with a total reflux- 96, 691 (1941). (11) Quigglc, Tongbag and Fenrke.Ind. E s g . Chum.,Anal Ed , 6 , partial take off head. Tested with toluene and methylcyclohexane, by the method of Fenske,$ 488 (lW4). (12) The Hoffman Micrornalytical Laboratories, Denver, Colothis column rated 19 plates rado 19) Penake, Ind En# Chrm , 94, 482 (1932)
(13) J Vnmer. Thesis, The Ohio State U n i v d t y , 1943.
further chlorination A gave only CH&FKClrCH1 and CHICF&2HC1CH*Cll while B gave CHaCFsCHSCHCl,, then CH&F&HtCC& almost exchSively. These results show that the chlorination is directed away from an alpha CHa group, and tends to accumulate the chlorine atoms on the same carbon atoms. The failure of CH&1CF2CHzCHa to be chlorinated to CHC12CFtCHrCHa confirms the direction awav from a terminal gmup alpha to A CF2 group.
[CONTRIETJTION FROM
THE
Chlorine reactivity tests show that alpha chlorine atoms are immobilized and that beta chlorine atoms are repressed, while gamma chlorine atoms seem to be unaffected. COLUMBUS, OHIO
RECEIVED b h Y
7,lw"
(14) TW nvnlucript WM originaUy d v d on sep~llllkr14. 1943. aad after aumhtiion by the editodd board w u .eaptdfar publiatioa in Tma JOW~NA:.. It was, however, r e f a d to the NatiahPI Defenae R-h Committee and at their request waa withheld from pubtiation, in a m6dential file. until clarsncc was m t e d om May 6, 1946.
DBPARTMENT OF CWSMXSTRY AT THEOkio STATE UNIVERSITY 1
The Synthesis and Directed Chlorination of
1,1,1,-Trifluorobutane
BY ALBERT L. HENNEAND JAMES €3. HINKAMP
To find out how far a CFa group would extend its influence, trifluorobutane, CFsCHsCH2CHaI was synthesized and subjected to the action of chlorine. The synthesis probiem consisted in devising a practical method for obtaining an intermediate compound, CCldHCHSCH,, from which the desired CFaCHL!HtCHs was made by variations of the procedures previously used to synthesize CFICH~CHII.~ The chlorination as well as the isolation and identification of the chlorinated compounds were performed in a manner previously described.l l 2
satisfactory. The addition of chlorine which synthesizes CHClsCHClCHpCHs was performed in the dark to prevent substitution. Pilot tests showed that water would greatly accelerate the rate of addition, but at the expense of increased substitution. When time matters little, it is best to operate without water, at about loo, and with a slight excess of olefin, for a net yield of 70-75%. In the presence of water, the reaction proceeds nearly four times faster, but the net yield drops to approximately 55%. The dehydrohalogenation of CHClrCHClCHsCHI proceeded very easily with either a ueous or Synthesis of CCh=CHCH2CHs alcoholic sodium hydroxide, and gave 98% of the The sequence CHOCHtCHPCH,, to CHCltCH2- desired CC12=CHCHnCHA. CHsCHa, to CHCl=CHCHzCHa, to CHC12Synthesis of CFsCH2CH2CHa CHClCHtCHa, to C C l d H C H & H a , was first tried. The transformation of butyraldehyde into At room temperature, C C l d H C H n C H , does its dichloride by means of phosphorus pentachlo- not react with hydrogen fluoride. When the ride gave only a 23% yield, which was finally temperature is raised, addition takes place to brought up to 39% by a series of time-consuming form CFClsCHSCH&Ha, then substitution occurs improvements. Since these improvements called to yield CFnClCH2CHsCHS. With longer reacfor hydrolysis of the reaction product at Oo, the tion periods, higher temperatures, and a greater risk of handling an incompletely hydrolyzed ma- excess of hydrogen fluoride, the formation of terial prevented their application to larger quan- CFtClCHzCH2CHs is progressively enhanced. tities. The dehydrohaiogenation to CHCl= A three mole quantity of CClr==CHCH&H8 CHCH2CHsrequired a saturated solution of potas- was mixed with 24 moles of hydrogen fluoride in a sium hydroxide in boilin butanol, and gave 64'% steel container surmounted by a one meter length of olefin together with 2 9 h o recovered dichloride. of half-inch steel pipe bearing a pressure gage and For large quantities it was deeA.iedsafer and a releasing needle valve. The top twenty centimore economical to start from technical CHsCl- meters of the pipe were surrounded by a jacket CHC1CH2CHa. Dehydrohalogenation occurred which could be filled with Dry Ice. The reaction easily with a 30% solution of sodium hydroxide was started by puttiiig the cylinder in a hot water in denatured alcohol and formed only two of the bath, its progress being shown by an increase in possible three olefins. The reaction was sua- pressure due to the formation of hydrogen chlociently exothermic to maintain itself and it yielded ride. With Dry Ice in its container to ensure an 27% of CHt=CClCHtCHa, 46% of the desired efficient aephlegmation, the hydrogen chloride CHC1=CHCHrCHs and 16% of recovered di- was slowly released into a water absorber by chloride. Since CHFCClCH2CHa was easily operating the needle valve so as to maintain the transformed into CHSCFKH&HI used in the pre- pressure between 17 and 20 atmospheres. When ceding study,2 this procedure proved to be very the pressure no longer increased, the reaction vessel was cooled in Dry Ice, and its contents (1) Henne and Whalry, Txxs JOURNAL, U, 1157 (1942) were poured onto cracked ice, then worked up by (2) Hcnne and Hinkamp. ibid.. CT, 1194 (1946).
