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I N D U S T R I A L A N D ENGI-NEERING CHEMISTRY
(8) James and Morris, Ibid.,40,405 (1948). (9) King, Can. J . Research, 26F, 125 (1948). (10) Livineston. ENG.CHEM..41.888 (1949). , IND. ( l l j Livingston, Oil Gas J.,46, No. 45, 81 (1948). (12) Ibid., 47, No. 38, 67 (1949). (13) Livingston, Hyde, and Campbell, IND.ENG.CHEM.,41, 2722 (1949). (14) Mardles, J . Chem. SOC.,1928,872. (15) Midgley and Boyd, IND. ENG.CHEM.,14,849 (1922). (16) Moureu, Dufraise, and Chaux, Chernie et Industrie, 17, 531 (1927). (17) Mulcahy and Zipkin, Natl. Advisory Comm. Aeronaut., Wartime Rept., ARR E5E04a (1945).
671
(18) N. V. Bataafsche Petroleum Mj., Dutch Patent 53,153 (Sept. 15,1942). (19) Ogilvie, Davis, Thompson, Grummitt, and Winkler, Can. J. Research, 26F,246 (1948). (20) Schildwlchter, Brennsto$-Chenz., 19, 117 (1938). (21) Schulze and Buell, Natl. PetroEeurn News,27, No. 41,25 (1935). (22) Von Elbe and Lewis, IND.ENG.CHEM.,29,551 (1937). (23) Withrow and Rassweiler,Ibid., 25, 1359 (1933). RECEIVEDJune 21, 1950. Presented before the Division of Petroleum CHEMICAL SOCIETY, Chemistry a t rthe 117th Meeting of the AMERICAN Houston, Tex. Contribution 87 from Jackson Laboratory, E. I. du Pont de Nemours & Co., Inc.
PEROXIDES FROM TURPENTINE As Catalysts f o r 5” C . GR-S Polymerization G. S. FISHER AND L. A. GOLDBUTT Naval Stores Research Division, Bureau of Agricultural and Industrial Chemistry, United States Department of Agriculture, New Orleans, La.
I. KNIEL AND A. D. SNYDER Government Laboratories, University of Akron, Akron, Ohio T h i s work was undertalcen as part of a program of research looking toward the increased utilization of turpentine as a chemical raw material. Turpentine, an agricultural commodity obtained from pine gum, is produced in the United States to the extent of about 700,000 barrels a year-roughly 70% of the world supply. On exposure to air, turpentine and many terpenes spontaneously form organic peroxides similar to those which have been found useful in a number of industrial processes, especially as polymerization catalysts in the production of synthetic rubber, resins, plastics, and other products. Methods which could be adapted commercially were needed to make turpentine a practical source of such peroxides. Concentrating on this problem, the Naval Stores Research Division, Bureau of Agricultural and Industrial Chemistry, developed processes for the economical pro-
duction in good yield of peroxides from terpene hydro* carbons and hydrogenated terpene hydrocarbons obtained from turpentine. These peroxides have been evaluated by the Office of Rubber Reserve as catalysts for the production of “cold rubber.” Several of them, particularly pinane hydroperoxide and menthane hydroperoxide, were found on laboratory scale tests to be equal or superior to the commercial peroxides now in use for this purpose. Peroxides used in the production of synthetic rubber are based on benzene, which is in critically short supply, and would be even more critically short in a national emergency. The peroxides required for the production of the scheduled 760,000 tons of synthetic rubber in 1951 would provide a market for 500,000 gallons of turpentine; this would simultaneously release a corresponding amount of benzene.
T
Crude turpentine has been shown to be capable of peroxidation, and these oxidation products were found t o yield rates of polymerization comparable with those of cumene hydroperoxide (9). The work reported here wa8 a preliminary investigation designed t o iind out which of these hydrocarbons or types of hydrocarbons derivable from turpentine were most promising with regard t o ease of preparation of peroxides in high concentrations and effectiveness of the peroxides as replacements for cumene hydroperoxide in standard redox formulas for copolymerization of butadiene-styrene. Hence, the method of preparation of the peroxides was chosen on the basis of simplicity and general applicability. Hydrocarbon peroxides are prepared commercially by reaction of si tertiary alkyl sulfab with hydrogen peroxide (18) or by direct oxidation of the hydrocarbon in the form of a vapor (f7),a homogeneous liquid (a),or an aqueous emulsion (f0)with oxygen or air. If necessary, the crude products are concentrated. B y autoxidation hydroperoxides of turpentine (81),01pinene (f6),and pcymene (11)have been prepared in conceBtrations of at least 25%. Because this method is also applicable t o saturated hydrocarbons containing a tertiary carbon atom (6),i t was chosen for the present work.
HIS cooperative work on preparation and evaluation of peroxides from turpentine was inspired by the desire of the Office of Rubber Reserve on the one hand t o develop new peroxides for use in the manufacture of “cold rubber,” especially in view of a possible shortage of cumene during an emergency, and the desire of the Naval Stores Research Division, on the other hand, t o develop new uses for turpentine. Turpentine can supply a group of hydrocarbons of substantially the same molecular weight, all containing ten carbon atoms, but of varied structure. Gum turpentine is composed chiefly of aand @-pinene,which are bicyclic terpenes, b u t a number of monocyclic terpenes can be prepared from the pinenes by acid isomerization or by pyrolysis. These include dl-limonene (dipentene), terpinolene, a-terpinene, a-pyronene, and @-pyronene. Acyclic terpenes such as myrcene and allo-ocimene can also be produced from the pinenes by pyrolysis. I n addition, dipentene, terpinolene, and a-terpinene can be dehydrogenated to give p-cymene, hydrogenated to give p-menthane, or disproportionated t o give a mixture of the two. The pinenes themselves can also be hydrogenated to give pinane. Certain other turpentines yield a different bicyclic terpene, A3-carene.
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INDUSTRIAL AND ENGINEERING CHEMISTRY
Vol. 43, No. 3
oxygen was introduced through a fritted-glass pencil.
TABLE I. PEROX .IDATION
H YDROCARBONS
Time, Hours 45 72 45 90 45 72 30 24 40 96 30 2.5 30 14 9 30 80-85 120 85-90 70 85-90 29 Milliequivalents of peroxide per kilogram.
Hydrocarbons a-Pinene P-Pinene Gum turpentine An-Carene Limonene a-Terpinene a-Pyronene p Py r on en e p-Menthane
-
OF
Temp., O
c.
ggzy a
FROM
TURPEKTIKEagitation was used.
Peroxide Xumbera Crude Concentrated 1550 8300 1490 6900 1450 6500 2850 9500 1890 4500 1750 3800 1420 3600 950 2300 1880 8200 1420 6500 2250 9300 Method of Wheeler ( 8 0 ) .
-
EXPERIMENTAL
MATERIALS.All hydrocarbons used in this investigation were purified by fractional distillation through an efficient Podbielniak column of approximately 100 theoretical plates a t high reflux ratios. a-Pinene, boiling point = 52" C. (20 mm.), [a]? = +30.4", n2,0 = 1.4653, d i 0 = 0.8582, and P-pinene, boiling point = 59" C.
No other
For oxidations a t higher temperatures, the reactors mere 3necked flasks fitted with a gas inlet tube, a stirrer, and a condenser. These reactors were illuminated and held a t the desired temperature by a 200-watt incandescent lamp.
The progress of the reactions was followed by determinations of the peroxide number, substantially by the method of Wheeler (20). The theoretical peroxide number for the monohydroperoxide of a terpene, molecular weight 136.2, is 11,890. The temperature and duration of oxidation and final peroxide number (milliequivalents of peroxide per kilogram) for each crude oxidate are given in Table I. CONCENTRATION OF CRUDEOXID.4TES. The crude oxidates were concentrated by distilling off the unoxidized hydrocarbon below 60 O C. a t a pressure of less than 1nini., using water vapor as a carrier gas. The peroxide numbers of the concentrates are also given in Table I. These peroxide concentrates contained from 70 t o 95% of the total peroxide present in the crude oxidates. When allowance was made for the peroxide which came over with the distillate, recoveries were over 90% in all cases. These rcsults indicate t h a t the peroxides were not decomposed appreciably during concentration. POLYMERIZATION. Polymerizations of butadiene-styrene with these peroxide concentrates, with cumene hydroperoxide, and with diisopropylbenzene monohydroperoxide were conducted in accordance with the low-sugar redox formula a t 5" C.shownonpage 673. Polymerization data with this formula are given in Tables 11, 111,and Il-,
(20 mm.), [a]Y = -21.4", nY = 1.4790, d i n = 0.8705, were obtained by fractionation of gum turpentine. AWarene, boiling point = 65.5" C. (20 mm.), [y]z,"= +17.5", n z o - 1.4729, diD= 0.8641, was obtained by fractionation of ponderosa stump turpentine. Limonene, boiling point = 71" C. (20 mm.), [a]2,6 = +123.5", n? = 1.4720, d i 0 = 0.8415, was obtained by fractionation of a technical grade of citrus limonene. d-Limonene was used in most of the work because its high optical rotation facilitated analysis; however, dllimonene (dipentene) gave substantially the same results. TABLE 11. POLYMERIZATIOE; OF BCTADIEKE-STYREKE USINGPEROXIDES FROM a-Terpinene, boiling point = 67TURPEXTINE HYDROCARBOKS IN A LOW-STGAR REDOXFORMULA AT 5 " C. f17.5"C. (20 mm.), n%' = 1.4780, d i 0 = Peroxide Charged 0.8409, E?.,!;. = 54 (265.6 mp), was obPurity", As loo%c -4S Conversion, yo tained by fractionation of the dehydraPeroxide % As recd. peroxide mmolesd & T O h r . - I j h r . tion product of a-terpineol (19). a-Pinene 65.5 0.075 0.29 23 0.049 18 25 a-Pyronene, boiling point = 47' C. (20 0.113 0.44 0 074 69 45 .. @-Pinene 51.3 0.091 0.28 5 3 0.047 5 mm.), n*$ = 1.4656, d i 0 = 0.8334, E f ' C , G u 111 44.1 0,096 0.25 9 0.042 10 10 tuipentine 0.146 32 0.38 57 0.064 , . = 34 (263 mp), and 6-pyronene, boiling 13-Carene 65.9 0 056 15 14 0.22 0.037 14 point = 60" C. (20 mm.), n2$ = 1.4808, 0.112 42 0.44 48 0.074 .. Limonene 0.139 37.6 0 . 3 1 18 0,052 15 18 dO : = 0.8495, E?'& = 37.5(266 mp)) 0.196 0.44 10 9 0,074 a-Terpinene 0.164 were prepared by fractional distillation 18.2 5 0.18 4 0.030 '6 a-Pyronene 17.6 0.173 3 0.030 0.18 3 4 of a pyrolysis product of a-pinene ( 3 ) . p-Pyronene 12.5 0.20 0.271 4 0.034 3 4 p-Menthane, boiling point = 65.5p-Menthane 69.7 0 076 64 0.063 0.31 44 65 0,108 66" C. (20 mm.),.nSo = 1.4403, dzo = 0.44 56 0.075 100 , . 0.096 p-Cymene 44.3 0.26 25 22 0.043 25 0.8071, was obtained by fractionation 0 164 44 0,073 0.44 81 .. of a commercial sample of p-menthane. CHP 0.098 68.3 0.44 33 0,067 61 DIBP 49.6 0,109 p-Cymene, boiling point = 70.643 0.054 47 0.28 48 0.170 63 0.084 94 0.43 .. 70.8" C. (20 mm.), n y =1.4907, dzo = cz Based on analysis b y method of Wagner (18). 0.8572, was obtained by fractionation of Grams of peroxide of indicated purity Der 100 grams of monomers. commercial p-cymene. Grams of pure monohydroperoxide per 100 grams of monomers. Pinane, [ a ] ? = +21.3", n2$ = 1.4624, Rlillimoles of pure monohydroperoxide per 100 grams of monomers. d i 0 = 0.8566, was prepared by hydrogenation of a-pinene at room temperature using platinum oxide as the catalyst. TABLE 111. POLYXERIZATION OF BUTADIENE-STYRENE WITH PEROXIDES FROM Traces of residual a-pinene were removed p-MENTHANE A K D p-CYMENE IN A LOW-SCGAR REDOXFORMULA AT 5" C. by washing successively with concentrated sulfuric .acid, dilute base, and Peroxide Charged water. The pinane was dried over Purity', As Conversion, % __ sodium sulfate and filtered before use. Peroxide % As recd. ,",s.:%?c mnioles 4 hr. 8 hr. 12 hr. Cumene hydroperoxide (CHP) and p-Menthane 58 9 0,083 0,049 0.28 66 81 82 0.100 0.059 0.34 diisopropylbenzene monohydroperoxide 65 89 91 0.117 0,069 0.40 64 84 85 (DIBP) were commercial products. ~
p-Cymene
OXIDATION.The general technique of oxidation was as follows: For oxidations carried out a t 50' C. or below the reactors were 35 X 400 mm. borosilicate glass tubes illuminated by four 15-watt fluorescent lights and held at the desired temperature by proper placement of the lights, or by means of a water bath cooled with tap water. The
0.135 0,062 0.31 0.162 0.062 0.37 0.189 0.072 0.43 CHP 68.3 0.073 0.050 0.33 0.086 0.058 0.38 0.102 0.070 0.46 DIBP 49.6 0.101 0.050 0.26 0.121 0.060 0.31 0.141 0.070 0.36 Based on analysis by method of Wagner (29). Grams of peroxide of indicated purity per 100 grams of monomers. Grams of pure monohydroperoxide per 100 grams of monomers. Millimoles of pure nionohydroperoxide per 100 grams of monomers.
*
38.3
43 38 43 31 31 29 49 64 64
60 64 66 41 51 50 49 78 87
51
77 77 40
63 67 51
79 86
March 1951
I N D U S T R I A L A N D E N G I N E E R I N G CHEMI'STRY
673
of the diene, limonene (only about 1.5 times t h a t of the monounsaturated pinenes), can be explained by the fact Peroxide Charged that oxidation occurs primarily at a secConversion, % Puritya, As As ondary carbon atom alpha to a double Peroxide % As recd * peroxide mmolesd 4 hr. 8 hr. 12 hr. 0 068 0 053 0 31 50 85 86 bond, and only with difficulty a t a pri77 7 Pinane 0 082 0 064 0 38 50 82 93 mary or tertiary carbon atom in this 0 096 0 075 0 44 49 88 94 position. The exocyclic double bond in 0 070 0 048 0 31 22 42 50 68 3 CHP 0 084 0 057 0 38 24 46 69 limonene has no secondary carbon in 0 098 0 067 0 44 24 46 68 the alpha position. In accord with this DIBP 49 6 122 0 073 061 0 38 31 47 49 84 83 92 86 concept, camphene, which has only a 00 147 0 171 0 085 0.44 68 90 93 quaternary carbon atom and a tertiary Based on analysis b y method of Wagner (18). carbon atom alpha to the double bond, * Grams of peroxide of indicated purity per 100 grams of monomers. C Grams of pure monohydroperoxide per 100 grams of monomers. failed t o peroxidiae under the conditions d Millimoles of pure monohydroperoxide per 100 grams of monomers. used for the other bicyclic terpenes. The conjugated monocyclic terpenes oxidized rapidly, but the peroxidation POLYMERIZATION FORMULA (LOW-SUGAR REDOX) was accompanied by extensive polymerization. The final Ingredient Parts products were not only low in peroxide content b u t also Butadiene 71 5 very viscous. It is probable t h a t even the peroxides were Styrene 28 5 polymeric (6). The acyclic conjugated terpenes myrcene and Modlfier 0 2 Emulsifier 4 78 allo-ocimene gave even less peroxide and even larger amounts of Peroxides 0 05-0 07 Activator 2 229 polymer. Water (total) 180 A3-Carene oxidized rapidly and gave very good yields of peroxide. The relatively rapid rate of oxidation of A3-carene Polymerizations were also conducted in the following amine but there appears t o have been has been noted previously (I6), formulas: no previous mention of the identification of peroxides among the products of oxidation (IS). I n A3-carene there are two POLYMERIZATION FORMULAS (AMINE) methylene groups, each situated between a double bond and a 3Ingredient Parts membered ring. It seems likely t h a t the highly strained ring Formula I Formula I1 acts like a double bond in activating a n a-methylene group, so Butadiene 71.5 71 5 t h a t the Aa-carene structure is analogous t o that of linolenic Styrene 28 5 28 5 Modifier 02 0 2 acid, which is also very readily autoxidized. Emulsifier 46 4 1 Amine 02 0 2 The oxidation of pinane is of special interest because excellent 1 0 Electrolyte 0 8 yields of peroxide were obtained rapidly and the peroxide was a Peroxides 01 0 1-0 2 Water 200 200 very active polymerization catalyst. The ease of peroxidation of pinane was verified by numerous Polymerization data with these formulas are given in Tables V, oxidations. Under suitable conditions peroxide numbers as VI, and VII. high as 75% of the theoretical value for a monohydroperoxide could be attained by direct oxidation, and values as high as 95% DISCUSSION of the theoretical could be obtained after concentration. This o indicate t h a t the hydroperoxide is the major autoxida~ ~ ~ compar~son ~ t i of~ the~ tseems i t~ ~ OF pEROXIDES. tion Product, and t h a t the pinane hydroperoxide is fairly stable. ease of oxidation of the various hydrocarbons is complicated beThe following evidence also demonstrates the stability of the cause several factors, such as the initial rate of oxidation, the peroxide. After storage in an open tube in the laboratory for length of the induction period, and the rate of oxidation after the Over a month the Peroxide number Was unchanged. l k c o m induction period, all contribute t o the over-all rate. The length position did begin to take place if the peroxide W&'S heated above of induction period, in particular, is greatly affected by traces 120" C. At 170" about two thirds of the peroxide was decomof impurities, such as preformed peroxides and other hydroposed in 10 minutes. At 140' the decomposition was rapid enough carbons which are difficult t o eliminate. For example, various to bring the sample temperature to about 10' above t h a t of the samples of a given hydrocarbon having the same initial peroxide content may have induction periods and ultimate rates which differ enough t o obscure small differences that may exist TABLEV. POLYMERIZATION OF BUTADIENE-STYRENE WITH PEROXIDES FROM between different hydrocarbons. TURPENTINE IN AMINEFORMULA I AT 5 " C. However, a qualitative ranking of Peroxide Charged the hydrocarbons with regard t o ease Puritya, As As Conversion, % of peroxide formation could be made on Peroxide % As recd peroxide mmolesd 5 hr. 10 hr. 15 hr. the basis of the data in Table I. Limoor-pinene 65 5 0 150 0 098 0 58 20 22 22 0 093 0 56 11 10 11 0.182 nene was peroxidized about one and 51 12 15 14 turpentine 44 1 0 192 0 085 0 50 a half times as readily as a-pinene, which 18 20 19 An-Carene 65 9 0 112 0 074 0 44 was peroxidized a little more readily than' Limonene 37.6 0 278 0 105 0 62 5 9 10 2 4 6 0 328 0 060 0 36 @-pinene. Gum turpentine was inter0 346 0 061 0 36 1 1 2 0-Pyronene 12 5 0 542 0 066 0 39 1 2 2 mediate between a-pinene and P-pieene. 0 106 0 62 27 59 67 0 152 Menthane 69 7 This ranking was substantiated by oxida& ~ p 49.6 0 218 0 108 0 56 30 63 70 tion of samples of the hydrocarbons at Based on analysis by method of Wagner (18). Grams of peroxide of indioated purity per 100 grams of monomers. other temperatures. Grams of pure monohydroperoxide per 100 grams of monomers. Millimoles of pure monohydroperoxide per 100 grams of monomers. According to the theories of Farmer (7) the rather low rate of oxidation
TABLE IV. POLYMERIZATION OF BUTADIENE-STYRENE WITH PEROXIDE FROM PINANE IN A LOW-SUGAR REDOXFORMULA AT 5 " C.
Q
'
gzy
i;
'
674
INDUSTRIAL AND ENGINEERING CHEMISTRY
TABLE VI.
POLYhlERIZATIOK O F BUTADIENE-STYREXE WITH PEROXIDES FROZI p-MENTHAKE AND P-CYMER'E IN AMINEFORMULA I1 AT 5 " C.
Peroxide p-Menthane
Purity',
%
58.9
p-Cymene
38.3
CHP
68.3
DIBP
49.6
a
As 0.167 0.250 0.334 0,270 0.405 0.540 0.146 0.219 0.293 0.202 0,302 0.403
Peroxide Charged As loo%c As peroxide mmolesJ 0.10 0.57 0.15 0.86 0.20 1.14 0.10 0.62 0.15 0.93 0.20 1.24 0.10 0.65 0.15 0.98 0.20 1.31 0.10 0.52 0.15 0.77 0.20 1.03
4 hr. 14 17 20 13 14 18 18 18 19 22 24 25
Conversion, % 8 hr. 12 hr. 41 68 45 72 53 70 33 60 35 66 40 52 38 57 39 59 57 63 55 82 57 85 62 64
14 hr. 76 79 72 64 72 52 63 67 64 86 92 64
Based on analysis by method of Wagner (18). Grams of peroxide of indicated purity per 100 grams of monomers. Grams of pure monohydroperoxide per 100 grams of monomers. Millimoles of pure monohydroperoxide per 100 grains of monomers.
TABLE T'II.
POLYMERIZATION O F BUTADIENE-STYRESE WITH PEROXIDE F R O M P I N A N E IN AXINEFORMULA I1 AT 6" C.
Puritya,
%
Peroxide Pinane
77.7
CHP
68.3
DIBP
49.6
As
0.137 0.205 0,274 0.140 0.210 0.280 0.245 0.368 0.490
Peroxide Charged As loo%c As peroxide mmolesd 0.106 0.63 0.159 0.94 0.213 1.25 0,096 0.63 0.143 0.94 0.191 1.25 0.122 0.63 0.183 0.94 0.243 1.25
4 hr. 36 41 29 20 20 19 30 28 28
heating bath, but was not self-sustaining ~3 hen the sample was removed from the bath. The structure of the pinane hydroperoxide has not been proved, but autoxidation of saturated hydrocarbons is known to occur at tertiary carbon atoms ( 2 ) . Hence, it seems probable that the hydroperoxide group is attached to one of the three tertiary carbons in pinane. Shochet (14) has reported that autoxidation of pinane at 110" C. for 3 weeks produces an acetyl cyclobutane, This implies an attack a t the 2 carbon atom. Autoxidation of p-cymene to give hydroperoxides has been reported previously. Both the 7- and the 8-hydroperoxides have been reported (8, 11). The latter seems most likely, because other free radicals attack the molecule a t this position (1). POLYMERIZATIOX. Various peroxides must be regarded as substituent products; hence, substituent behavior has been regarded as the most important criterion of their usefulness. Because cumene hydroperoxide is the peroxide used commercially in making "cold rubber" and the monohydroperoxide of diisopropylbenzene is among the best peroxides available, these were used as standards in the evaluation of the peroxides from turpentine. Some caution must, of course, be used in interpreting and applying the results of the comparison of so many different products, because the observed differences might be minimized by changes in the polymerization formulas used. The data presented in Tables I1 and V indicate t h a t peroxides prepared by oxidation of pure conjugated terpenes a t about room temperature were practically inactive in the formulas used; t h a t from limonene was little better. The peroxide from or-pinene was fully comparable with cumene hydroperoxide in the low-sugar formula, but the peroxide from p-pinene showed surprisingly poor activity. Preliminary experiments in which cobalt driers were added during the oxidation of the hydrocarbon showed t h a t or-pinene formed approximately 15y0of peroxide and did not gel, whereas p-pinene formed only
Vol. 43, No. 3
5% or less of peroxide and gelled. These observations suggest that fundamental differences exist in the structure and stability of the two peroxides. The peroxide from gum turpentine, as might be expected, fell between a- and P-pinene, as did that from A3-carene. As shown in Tables I1 through VII, p-cymene hydroperoxide, p-menthane hydroperoxide, and pinane hydroperoxide were generally superior to cumene hydroperoxide in these formulas. Pinane hydroperoxide and p-menthane hydroperoxide were so nearly equivalent t o diisopropglbenzene monohydroperoxide and t o each other that the order of activity depended on the criterion chosen. LITERATURE ClTED
Conversion, 70 8 hr. 12 hr. 56 54 57 58 59 77 36 54 36 57 37 54 57 65 80 57 57 81
(1) Bickford, W.G., Fisher, G. S., Dollear F. G.. and Swift. C. E.. J . Am. Oil Chemists' Soc., 25, 251-4 (1945). (2) Creegie, R., Ber., 77B, 22-4 (1944). (3) Dupont, G., and Dulou, R., A t t i X. congr. intern., 3, 123-39 (1939). (4) Farkas, A., and Stribley, A. F., J r . , C. S. Patent 2,430,864 (194'7). (5) Ibid., 2,430,865 (1947). (6) Farmer, E. H., J . SOC. Chem. I n d . (London),66, 86-93 (1947). (7) Farmer, E. H., Bloomfield, G. F., Sundralingam, A., and Sutton, D. A., T r a n s . F a r a d a y SOC.,38, 345-56 (1942). (8) Helberger, J. H . , Rebay, A., and Fettbach, H., Bel.., 72B, 1643-5 (1939). (9) Kniel, I., private communication from Government Laboratories to Office of Rubber Reserve. (10) Lorand, E. J., U. S.Patent 2,484,541 (1949). (11) Lorand, E. J., and Reese, J. E., Ibid., 2,438,125 (1948). (12) hlilas, N. A., Ibid., 2,223,807 (1941). (13) Owen, J., and Simonsen, J. L., J . C h e m . SOC.,1931,3001. (14) Shochet, D., Bull. S O C . chim. b e l g . , 44,387-94 (1935). (15) Simonsen, J. L., J . Oil and Colour Chemzsts' Assoc , 20, '78-90 (1937). (16) Susuki, K., Bull. Inst. P h y s . Chem. Research ( T o k y o ) , 14,179-91 (1935). (17) Vaughan, W. E., and Rust, F. F., U. S. Patent 2,403,722 (1946). (18) Wagner, C. D., Smith, R. H., and Peters, E. D., A n a l . Chem., 19, 976-9 (1947). (19) Wallach, O., and Kerckhoff, F. Ann., 275, 106-5 (1893). (20) Wheeler, D. H., Oiland S o a p , 9,89 (1932). (21) Yamada, T., J . Soc. C h e m . I n d . ( J a p a n ) (Suppl. Bind.), 39, 18994 (1936).
RECEIVED June 19, 1950. The part of this cooperative work performed a t the Government Laboratories and reported herein was carried out under the sponsorship of the Office of Rubber Reserve, Reconstruction Finance Corporation, in connection with the government synthetic rubber program.
