January, 1946
I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY
TABLE 11. RELATIVEVELOCITY OF CRYSTALLIZATION OF SYNTHETIC MOLASSES AT 30’ C. AND ~ € 1 8 Initial Composition, % Purity, % 2.9 NaC1, 8.8 invert, 63.8 sucrose, 24.5 water 84.5 2.1 NaC1, 32.6 invert, 47.2 sucrose, 18.1 water 57.5 1.8 NaC1, 43.6 invert, 39.4 sucrose, 15.2 water 46 5.0 raffinose. 5.8 betaine. 64.4 sucrose. 24.8 water 85.5 4.9 ra5nose, 5.6 betaine, 2.8 NaC1, 62.6 sucrose, 24.1 water 82.5
.
velocity of C r y s g . Obsvd. Calcd.
0.27
0.38
0.09
0.09
0.01
0 03
0 20
0.13
0.08
0.11
ACKNOWLEDGMENT
The author acknowledges the support given this work by the Sugar Research Foundation and the assistance, through supplying samples of many of the contaminants used, of the Chemistry Department of the University of Wyoming (amino acids), E. K. Ventre of the Baton Rouge Station, U. S. Department of Agriculture (aconitic acid), and the Western Regional Research Laboratory (citrus pectins).
53
(4) Dahlberg, H. W., Proc. Am. Soo. Sugar Beet Tech., 3, 323 (1942). (5) Dubourg, J., and Saunier, R., Bull. SOC. chim., 6, 1196 (1939). (6) Grut, E. W., Listy Cukrovar., 56,37 (1938). (7) Hungerford, E. H., and Nees, A. R., IND. ENG.CHEM.,26, 462 (1934). (8) Hungerford, E. H., and Nees, A. R., Proc. Am. Soc. Sugar Beet Tech., 3,499 (1942); Intern. Sugbr J., 46, 323 (1944). (9) Ingelman, Bjarn, The Svedberg (Mem. Vol.), 1944, 156. (10) Kauznetzov, A. F., Sucr. belge, 45, 9 (1925). (11) Krasil’shchikov and Tsab, Khim. Referat. Zhur., 1940, No. 1011, 126. (12) Kucharenko, I. A., Planter Sugar Mfr., 75 (May-June, 1928). (13) Landolt-Biirnstein,Physikalisch-Chemische Tabellen, 1936. (14) Lebedeff, S., Z. Tier. deut. Zucker-Ind., 1908,599. (15) Nakhamovich and Zelekman, Nouch. Zapiski Sakharnol Prom., 6, 32, 109 (1928). (16) Naveau, G., Sucr. belga, 62, 310, 336 (1943). (17) Nees, A. R., and Hungerford, E. H., IND.ENG.CHEM.,28, 898 (1936). (18) Reich, G. T., Ibid., 37, 53G (1945). (19) Sandera, Chimie & Industrie, 1933, 1147. (20) Schukow,I., 2. V e r . deut. Zucker-Ind., 50, 291 (1900). (21) Smolenski, K., and Zelanzny, A., Gaz. Cukrownicza, 74, 303 (1934). (22) Spencer-Meade,Cane Sugar Handbooks, 8th ed., 1944. (23) Thieme, J. G., “Studies in Sugar Boiling”, tr. by 0. W. Willcox. New York. Facts About Sugar. 1928. (24) Van Hook, Andrew, IND.ENO.CHEM.,36, 1042 (1944); 37, 782 (1945). (25) Van Hook, Andrew, and Shields, D., Ibid., 36, 1048 (1944). (26) Verhaar, G.,Arch. Suikerind. Nederland en Ned. I n d i l , 1,324,464 (1940). I
LITERATURE CITED
(1) Affernii, E., Ind. snccar. ital., 27, 319 (1934). ( 2 ) Amagasa and Nishizawa, J . Soc. Chem. Ind. Japan, 39, Suppl. binding, 263 (1936) (3) Ambler, J. A , , Turer, J., and Kennan, G. L., J . Am. Chem. Soc., 67, 1 (1945).
PRESENTED on the program of the Division of Sugar Chemistry and Technology of the 1945 Meeting-in-Print, &ERICAN C H ~ M I C A SOCIETY. L
roduction of Isoprene from Turpentine Derivatives B. L. DAVIS’, L. A. GOLDBUTT, AND S. PALKIN2 Naval Stores Research Division U . S . Department of Agriculture, New Orleans, La.
I
SOPRENE, C,H8 (a homolog of butadiene), has been used
extensively as a copolymer in the production of syethetic elastomers. According to reports (9), it is utilized in the preparation of Butyl rubber. It constitutes a n essential monomer for certain neoprenes and is of value for the production of special Buna S type elastomers. Terpene hydrocarbons, C10H16 (dimers of isoprene), particularly terpenes derivable from turpentine, have long been regarded as a logical source for the production of pure isoprene, and figured prominently in early investigations and patent literature. Turpentine, consisting almost wholly of terpene hydrocarbons (over 98%), is an abundant commercial product, and the United States produces about two thirds of the world’s supply. Isoprene was first isolated in a reasonably pure state by Williams (2%) who applied the name “isoprene” t o a liquid fraction boiling between 37’ and 38’ C. (specific gravity 0.6823 at 20’ C.) which he obtained by distilling rubber. Tilden (21) first prepared isoprene from turpentine by passing the vapors through a red hot tube. H e obtained about a 2% yield of a fraction boiling between 37” and 40” C. The further discovery by Tilden (89) that isoprene polymerizes to rubber led to considerable experimental work on the production of isoprene from terpenes. Claims of isoprene yield up to 70% from various terpene frac1 2
Present address, Bureau of Animal Industry, Washington, D. C. Deceased May 2, 1943.
tions have been made in the patent literature (9, 4, 7 , 14, i 7 , 18, 20, 24). However, from other available literature (1, 6, 8, 10, 19, 13, 16, 19, 26)it is apparent that, in spite of occasional claims of high yields and purity (usually not confirmed by subsequent investigators), only small amounts of isoprene of doubtful purity can readily be obtained from turpentine or the terpenes by the methods so far described. I n 1942 Palmer (16) reported that isoprene was being produced commercially from terpenes, and that it was possible t o make isoprene of very high purity by this process. No details were given as to the process or the terpenes utilized. I n the investigation reported here the method of carrying out this depolymerization involved the use of a n electrically heated, glowing wire coil immersed in the liquid terpene itself; provision was made to allow low-boiling products, including the isoprene, to escape as rapidly as possible from the reacting medium. Although the wire coil is immersed in the liquid terpenes, the pyrolysis is actually that of a vapor phase system, since the coil is so hot (about 750’ C.) that liquid is not in actual contact with it. The products of pyrolysis are quickly removed from the hightemperature zone and cooled by the vigorously boiling liquid terpene. Further, the isoprene produced is only slightly soluble in the relatively high-boiling terpenes a t their boiling point, so there is comparatively little bpportunity for the isoprene t o be subjected to further pyrolysis. Figure 1is a diagram of the pyrolysis apparatus.
INDUSTRIAL AND ENGINEERING CHEMISTRY
54
Vol. 38, No. 1
T h e production of isoprene from terpenes derivable from turpentine by pyrolysis with an immersed, electrically heated, glowing wire coil was investigated. Dipentene (d,Z-Iimonene) gave the best yields (about 60%); 8pinene, myrcene, turpentine, a-pinene, terpinolene, and allo-ocimene gave progressively lower yields. High-purity isoprene was isolated from the dipentene pyrolyzates by fractional distillation through a short glass Bruun column, but the isoprene from the other pyrolyzates could not be purified so readily. The loss as gas not condensed by dry ice was in inverse proportion to the yield of isoprene, and
ranged from less than 4 to more than 30%. Comparatively little difference in isoprene yield was observed when a platinum or a nickel-chromium resistance wire was used. Somewhat improved yields from dipentene were obtained by use of a high-boiling diluent or reduced pressure. Liquid products, other than isoprene, during the pyrolysis of dipentene consisted of 30% each of unsaturated acyclics, unsaturated cyclics, and aromatics, and about 10% of dimer. The noncondensable gas consisted of methane (45%), hydrogen (30%), ethylene (20529, and less than 5% of olefins higher than ethylene.
PYROLYSIS APPARATUS
ratory funnel placed between the reflux condenser and the dephlegmator. Soncondensable gas produced was measured by a wettest gas meter (metric calibration) or, in the case of runs made below atmospheric pressure, by a calibrated flowmeter. The pyrolyzing coil for most of the runs was made of commercial nickel-chromium resistance wire (chromel A). Little difference in the yield of isoprene was observed when a platinum wire \Tag used. Both wires carbonized slightly, the platinum wire somewhat more. Finer wires glowed and gave pyrolyzates with relatively lower power consumption. Although these finer wires B. Bi S. No. gave satisfactory pyrolyzat,es, they were fragile; 25 chromel A or No. 30 platinum wire was about as fine as could be used with assurance of reasonable durability. With a given wire, a n increase in wattage, after pyrolysis began, largely increased the rate of yield of pyrolyzate, but this effect was RCcompanied by a disproportionately large increase in gas production. I n general, wattage was adjusted to yield pyrolysates (dry ice condensates) a t the rate of about 5 cc. (3 to 4 grams) per minute. Under these conditions power consumption was generally approximately 760 watts which, in the case of dipentene, represented somewhat less than 5 watt-hours per gram of isoprene produced. A No. 25 wire, wound to give a coil of approximately l/a-inch diameter, gave somewhat better results than a coil of approximately '/,-inch diameter, using as a criterion the ratio of volume of noncondensable gas (noncondcnsable by dry ice-acetone) t o the volume of pyrolyzate. Coils of smaller diameter than 1/8 inch gave practically the same results.
The pyrolysis vessel consisted of a three-neck, one-liter, roundbottom Pyrex flask. The two side necks were provided with standard-taper 24/40 ground-glass joints, and the central neck with a standard-taper 34/45 ground-glass joint. The two 24/40 joints were fitted with hollow ground-glass stoppers having a 5inch length of tungsten wire sealed through each. At the lower end of each of these tungsten lead-in viires was a solid brass rod, 3 inches long and l/r inch in diameter, drilled lengthwise a t each end; one end admitted the tungsten lead-in wire, and the other took one end of a spiral resistance wire used as a pyrolyzing coil. Each rod was also drilled and ,happed on the side for machine screws to hold the tungsten lead-in and resistance wires. The coils were prepared by winding the resistance wire on l/g- or l/,inch metal rods on a lathe. Electric power was supplied t o the coil, usually of about IO-ohm resistance, from a 110-volt alternating current line and was controlled by a variable transformer capable of carrying a current of 18 amperes (type 100 Q Variac). A Dimroth-type spiral reflux condenser was fitted into the central joint and served to return unreacted terpene. The products of pyrolysis passed to a dephlegmator cooled with a mixture of dry ice and acetone for runs a t atmospheric pressure or with liquid air for runs a t the lowest pressure. Provision was also made for the addition of fresh terpene during a run, if desired, through a sepa-
Figure I ,
R E A C T I O N SYSTEM A -VARIAC TYPE 100 Q
B -AMMETER
G -REACTION FLASK D -TUNGSTEN ELECTRODE
E -BRASS CONNECTOR F -PYROLYZING COIL G -CONDENSER h'-ADDITION FUNNEL -DEPHLEGMATOR J - D R Y ICE-ACETONE K -RECEIVER f -GASMETER
DISTILLATION OF PYROLYZATES
The pyrolyzates were fractionally distilled through a glass bubble-plate (eleven-plate Bruun) column, fitted with a watercooled reflux condenser, a stopcock for reflux ratio control, a receiver equipped with a dry ice-acetone cooled reflux dephlegmator, and a pressurerelief vent from the water condenser to the receiver (Figure 2). The isoprene content of t,he fractions boiling below 40" C. was estimated by consideration of the physical constants, especially refractive index and boiling point. Since the refractive index of isoprene (n'; = 1.4216) is much higher than that of any other compound which might reasonably be expected in these fractions, the refractive index served as a convenient criterion of and guide t o purity. Trimethylethylene (2-methyl-2butene) is perhaps the most likely contaminant. I t s boiling point is 38.6' C., and its refractive index, n2: = 1.3876. Also, its refractive index is closer to that of isoprene than that of any other probable contaminant. By considering trimethylethylene as the impurity preeent, therefore, a minimum (or conservative) value for actual isoprene present is obtained. The difference between the refractive indices of isoprene and trimethylethylene is 0.0340. One per cent of impurity,
January, 1946
INDUSTRIAL A N D ENG INEERING CHEMISTRY
5s
TABLE I. PYROLYSIS OF 1-LIMONENE
-
-
-
[B.& 6. No. 28 ohromel A wire, wound on l/a-inch rod; 500 grams of 2-
limonene (d:'
F R A GT I 0 N AT I N G COLUMN ASSEMBLY
Time, Min.
4 -VARIAC TYPE 200 CM
8 -500-CC.FLASK WITH
c
"GLAS- COL" - 1 I-PLATE BRUUN COLUMN
0 - J A C K E T WITH HEATER COIL
ng
1.4731; ag in 10-cm. tube -79.19O; 75 mm. pressure)] Variac Setting, Current, Pyrolysate, Volume of Volts Amperes MI. 80 7.30 0 80 7.62 42 80 8.00 105 75 7.82 173 74 7.80 227 74 7.85 282 74 7.88 308 Shutdown
0.8431;
...
E -STILL HEAD
...
233.0 grama ag (10-om. tube) 258.0 Pyrolyzate 15.81 Residue -63.95 491.0 9.0 Loss (a8 gas) 500.0 grams % Limonene in pyrolyzate (estd. from oDtical activitv of whole pyrolyzate>. 20.0 Limonene in pyrolyzate (estd. from optical activity of separate fractions obtained on fractional distn. of pyrolyzate) 2 0 . 3 Limonene in residue (estd. from optical activity of whole residue) 80.8 Isoprene in pyrolynate (estd. from refractive index of fractions obtained below 40' C.) 65.0 Over-all yield of isoprene 61.0
f -DRY I C E - A C E T O N E
Pyrolyzate Residue
G -RECEIVER
-
. I _
-
TABLE 11. DISTILLATIONOB LLIMONENE PYROLYZATE OBTAINED AT 7.5 Mu. Fraca 5' tion Grams Per Cent B.P., C. fly (10-Cm. Tube) I I1 I11
IV
V VI
8.7 16.5 68.4 41.4 18.5 46.7
4.3 8.3 34.2 20.7 9.3 23.3
To32 33 34 40 147 To 171and pulldown
1.4206 1.4201 1.4214 1.4215 1.4848 1.4745
.... .... - .... 3.45' . I . .
-67.11'
that of isoprene obtained. The loss as gas ranged from less therefore, would change the refractive index by more than than 4% of the weight of pyrolyzate with dipentene to more than 0.0003. Data obtained in this way were frequently confirmed 30% in the case of allo-ocimene. I n addition (not shown in by quantitative estimation of total conjugated diolefins by reacting with . maleic anhydride. The amount of original Table 111), the isoprene-containing fractions that boiled below starting material carried over into the pyrolyzates collected was 40' C. were much purer in the case of dipentene. also approximated from these fractional distillations; in the case of those compounds of high optical rotation, such estimates were ISOPRENE FROM &LIMONENE in close agreement with estimates made simply by measuring the The results of typical runs under varying conditions are given optical activity of the pyrolyzate as a whole. The amount of in Table IV. Decreased pressure serves to increase the yield of unchanged terpene in the residue in the pyrolyaing flask was usually determined by fractional distillation or, especially in the case of the compounds of high 200 1.4800 optical rotation, from the optical activity. Estimates based on optical activity, especially for [-limonene, agreed quite closely with those made I75 1.4700 on the basis of fractional distillation. Data obtained from a typical pyrolysis are I50 1.4600 presented in Table I. Figure 3 gives refractive .o w' index and boiling point data obtained on distilling 3 125 1.4500 ? a typical l-limonene pyrolyzate. Other signifix % cant data for this pyrolyzate are listed in Table a z 11. 5 100 1.4400 w Results indicating the percentage of isoprene 0 in the pyrolyzate and the volume of gas produced, 75 I4300 U. for a few representative terpenes, are given in Table I11; typical distillation curves for the Li pyrolyzates are shown in Figure 4. The percent2i 50 I. 4200 age of isoprene in the pyrolyzate is in inverse ratio to the volume of gas produced, and di1.4100 25 pentene (d, I-limonene) is distinctly superior to any of the other terpenes as t o both the percent0 age of isoprene in the pyrolyzate and the small 0 IO 20 30 40 50 60 70 SO 90 IO0 PERCENT BY WEIGHT amount of gas produced. I n the case of a-pinene and allo-ocimene, the weight of noncondensable Figure 3. Distillation of Limonene Pyrolyzate Obtained at 7.5 Mm. Pressure gas lost was about equal t o or even exceeded
z
3
,56
INDUSTRIAL AND ENGINEERING CHEMISTRY
Vol. 38, No. 1
18%,). The pmxntage of unsatura.ted hydrocnrboris obtained was higher than for limonene, ranging from 26 with terpinolcne to SOTG with 0-pinene. Chmparison of the density of the gases, computed on the basis of the indicatcd composition, with the measured volume of gas obt,ained and losses sustained during pyrolysis, indicates fair agrcement. Thc facts that' not all losses during t'he pyrolysis are due t o gassing alone and t,hat the unsaturat,ion may be due t o a diolefin greatcr t'han C8 could adequately account for the discrepancies hetiwen the observed and calculated densities.
180
160
140
Y W
a 3 120 a I Y W
a
=
w 100
c
z
-
0
t;
ANALYSIS OF LIQUlD PRODUCTS 80
The liquid products, other than isofrom both the pyrolyzat,e and prene, t-m t'he residue resulting from the pyrolysis * 60 of limonene were examined further, This material, exclusive of unchangcd limonene, comprises about 36T0 of 40 the limonene altered. As indicatcd by the distillation data. of the pyrolysates, this mat.eria1 consists of a 20 complex mixture of substances, probably containing both cyclic arid acyclic aliphatic and many aromatic compounds. 0 The method of analysis depended on: ( a ) fractionat>ionof this material, using the Bruun column; ( b ) measurement of Figure 4. Distillatioil Curves of Terpene Pyrolyzates unsaturation by t.he bromine adtlition number method of Uhrig and Leviri isoprene and to decrease gas production and power consumption (as),consisting of titration of the olefin in chloroform with bromine in glacial acetic acid; and (c) measurement of the specific The use of diphenyl as a diluent increases the yield of isoprene but also slightly increases gas production and materially increases power consumption. I n addition, some increased carbonization occurs, but even so the total amount of carbon formed amounts TABLE 111. PYROLYSIS O F REPRESBNT-44TIVE TERPENES to only a few tenths per cent of the pyrolyzate formed. Use of Gas per Gram 5% Isoprene -benzene as a diluent increases the gassing (a small amount is due of I s o p rIbIg.r ene In py- Over.ali Terpene AI1.b rolyiate yield t o pyrolysis of benzene) and increases the power consumption Useda Purity without materially affecting the yield of isoprene. 54 70 1-Limonened 98+% 23 210 &Pinene Samples of the gases not condensed by dry ice-acetone were 21 250 kircene 14 840 Turpentine cullected from the runs made a t atmospheric pressure and ana1550 13 0-Pinene 180-81 98+% C. lyzed for olefins by two essentially different methods. The 11 2600 Terpinolene 5 4000 Allo-ocimene 95+% Matuszak method (1I) is based on the differential absorption of Cs, CJ, and C, olefins by *varying concentrations of sulfuric acid. The method of McMillan el al. (9) is based on catalytic hydrogenation, except that palladium instead of a nickel catalyst was a s produEta of the vapor-phase pyrolpsia of a-pinene a t about 375' C . Terused. I n general, the results obtained by the two methods agreed pinolene was a commercially available sample. reasonably well. Table V summarizes the rcsults of these gas Measured by gas meter. C Calculated on basis of loss during pyrolysis. analyses. d No significant difference was observed when d , 2-limonene (dipentene) wa3 used. Table V shows t h a t the gases obtained from the pyrolysis of Z-limonene a t atmospheric pressure consisted of methane (4597,), hydrogen (30%), ethylene (20y0), and rather less than 5 % of oleTABLE IV. PYROLYSIS OF GLIMONENE fins higher than ethylene. Calculation of the density of a gas of Av. G r a m Over-all" Watt-Hr. hI1. Gas this composition agrees reasonably well with the density obtained Pyrolyzate Yield of per Gram per Gram Distinguishing by considering all the losses during pyrolysis, as gas. The gases Isoprene per Min. Isoprene, %; Isoprene Feature of Run obtained from the pyrolysis of the other terpenes were of the same 70 4.8 3.6 54 755-mm. pressure 50 3.8 4.1 61 75-mm. pressure general character, differing chiefly in the proportions of the vari20 3.6 3.3 63 7.5-mm. pressure 59 80 9.7 3.2 Diphenyl diluent ous components. I n general, the hydrogen content was lower 150 8.1 3.1 55 Benzene diluent than with limonene, ranging between 10 and 20%, except in the 0 Over-all yield of pure isoprene is based on total limonene altered in any case of myrcene which had 35VG hydrogen. The gas from Pway-e.g., by racemization, isomerizFtion, polymerization, or pyrolysis--as indicated by changes in optical rotation. pinene contained about twice as much hydrogen when a platinum pyrolyzing coil was used instead of chrome1 A (34 compared t o J
1
~~
~~
January, 1946
INDUSTRIAL AND ENGINEERING CHEMISTRY
57
dispersion and evaluation of the TABLE V. ANALYSES OF GASES NOTCONDENSED BY DRYICE-ACETONE amount of aromatic compounds Unsatupresent according to the tables Unsaturates5 Absorbed, % rates by Methane of Grosse and Wackher (6). B 66% By 87% B ' 100% Total by Catal sis, Hydro- by Differ- Grams per TerpeneUsed &SOr HzSOs &SO, Hn80r pen, % ewe, % Obsl-d. Calcd. The results of this analysis Limonene 4.5 0.5 20 25 24 , 30 46 0.60 0.61 (Table VI) may be summarized Limonene + * diphenyl 2.5 0 20 22.6 19 31 50 0.79 0.57 as follows: Fraction I was highly Limonene 0 32.5 32.6 44 10 46 0.77 0.80 unsaturated, having about one ben~ene 0 26 35 1.03 0.75 Limonene vapor .... .. ... .... .... 39 double bond for each C6 to Ce a-Pinene *.. .... .... 42 10 48 0.82 0.86 @-Pinene unit, and contained a considera18 32 0.72 0.82 Chrome1 A ... .... .... 50 34 24 0.81 0.62 33 39 Platinum i:5 1.5 ble amount of isoprene. Frac42 48 13 39 0.77 0.88 22 30.5 Turpentine 1 7.5 51 0.93 0.78 tion I1 was still highly unsatu14.5 21 33 Allo-ocimene 4.5 2 57 0.76 0.72 13 20 26 Terpinolene 4.5 2.6 rated, having an average of 0.76 0.67 41 43 46 36 l7 18 Myrcene 0.5 1.6 about 0.6 double bond per C6 Per oent by volume. under the conditions used, 667 HnSOi readily absorbs isobutyl e and higher olefins; propylene, butadiene, add n-butenes are absorbed by 87$ HISOG loo.% HzSO4 is requirsrtnto @sorb ethylene. unit, but also probably contained b Volume % hydrogen absorbed: preaence of acetylenic linkages or diolefins would result in high valuea in comconsiderable aromatics. Fracparison with total unsaturates as determined by absorption in HzSO4. 0 Temperature, 26O C.; pressure, 755-760 mm. tion I11 showed an average of less than 0.5 double bond per C I unit and apparently contained up to 65% aromatics. Fraction IV TABLE VI. ANALYSISOF NONISOPRENE LIQUID PRODUCTS FORMEDFROM &LIMONENE contained almost 10% limonene, showed a n average of about 0.5 double bond per CSunit, and also contained about 65% aro205.3 0.6918 1.4241 201.4 0 16.6 35-70 0 I matics, which appeared t o be 175.7 0 6211 125.4 0.7818 1.4605 70-100 I1 12.5 0.6 69.5 15.4 100-125 - 00.52' 95.7 174.0 0.8340 1.4781 I11 largely xylene. Approximately 23.2 125-150 81.0 0,8478 1.4848 166.3 9.4 67.7 --337.51; 41.6 32.4 27 149.1 0.8422 1.4759 147.5 V IV 18.3 150-163 half of the nonlimonene compo-43.52; 176.3 0,8390 1.4739 144.3 54.5 22.5 VI 20.6 163-170 nents of fractions V and VI were -67.22 199.0 0,8398 1.4721 130.5 84.0 0 VI1 82.3 170-172 203.5 0,8401 1.4716 130.2 92.5 0 VI11 133.6 172 -73.89" aromatics. The next three frac-73.70' 203.5 0.8404 1.4721 130.4 92.2 0 IX 22.8 173 65.4 42.1 X 19.0 Pulldown -52.24° 1.4852 159.4 188.4 0,8583 tions, comprising about 22% of Charged 385.4 grams the whole, were highly unsatuTotal all fractions 364.3 grams rated, showing about two double 17.2 g r a m Reaidbe 381.5 gram bonds per Cto unit and no Column holdup and loss 3.9 grams aromatic content. Thus, a t 385.4 grams leabt 22% of cyclic dienes isomeric with limonene appeared to be present. This is especially significant, becauseif any p-cymene were formed, which might be liquid products of pyrolysis (other than isoprene and unchanged expected, some should be found here. The final fraction (pulllimonene), which comprise about 35% of the limonene altered, down) was still high in limonene content; although the dispersion consist of unsaturated acyclics, unsaturated cyclics, and aroindicated that the nonlimonene portion was chiefly aromatic in matics in about equal proportions (about 30% of each), the renature, the other physical characteristics (refractive index and mainder being polymer (dimer). The acyclics are chiefly unsaturated hydrocarbons greater than CS;the unsaturated cyclics are density) fitted in much better with a polymer (dimer) than with an aromatic such as p-cymene. chiefly isomers of dipentene, although the presence of unsatuSummarizing the preceding discussion and basing conclusioh rated cyclics of lower molecular weight is also indicated. The on an evaluation of the data with respect to boiling point, refracaromatics seem t o be chiefly xylene with some toluene, but tive index, density, optical rotation, and specific dispersion, the apparently little or no p-cymene.
%r
+
LITERATURE CITED
Rekkedahl, N., Wood, L. A,, and Wojciechowski, M., J. Research Natl. Bur. Standards, 17,883 (1936). (2) E'rolich, P. K., Hearing before Subcommittee of Committee on Mines and Mining, House of Representatives. Production of Gasoline, Rubber, and Other Materials from Cod and Other Products. July 15,1942,table p. 91. ( 3 ) Gottlob, K., Brit. Patent 18,431 (1911); German Patent 249,947(1910); U.S. Patent 1,065,522(1913). (4) Gross, C. K.F. L., U. 8. Patent 1,099,498 (1914). (5) Grosse, A. V., and Wackher, R. C., IND. ENG.CHEM.,ANAL. ED., 11, 614 (1939). (6) Harries, C.,and Gottlob, K., Ann., 383, 228 (1911). (7) Heinemann, A.,Brit. Patents 14,040and 24,236 (1910), 1953 (1912): U. S. Patents 1,092,838 and 1,095,395 (1914), (1)
1,159,380(1915). (8) Herty, C. H., and Graham, J. O . , J. IND. ENQ.C H ~ M6, . , 803 (1914). (9) McMillan, W. A,, Cole, H. A., and Ritchie, A. V., IND. ENQ. CKEM.,ANAL.ED.,8,105 (1936). (10) Mahood, S.h.,J. IND. ENG.CHEM.,12,1152 (1920). (11) Matuszak, M.P., IND. ENG.CHEM.,ANAL.ED., 10,354(1938). (12) Mokijowsky, W.A, Chem.-Ztg., 28,991 (1904).
Muntwyler, O., thesis, Zurich 1917; Schotz, S. P.,"Synthetic Rubber", p. 94,London, E. Benn, 1926. Ostromislensky, I., U. 5. Patent 1,108,781(1914). Palmer, R. C.,IND.ENQ.CHEM., 34, 1034 (1942). Schorger, A. W.,and Sayre, R., Ibid., 7,924 (1915). Silberrad, O.,Brit. Patent 4001 (1910); U. S. Patent 1,022,338 (1912).
Staudinger, H., German Patent 257,640 (1913); U. S. Patent 1,065,182 (1913).
Staudinger, H., and Klever, H. W., Ber., 44, 2212 (1911). Stephan, K. (to Schering and Co.), U. S. Patent 1,057,680 (1913).
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Waltereck, H. C., Brit. Patent 27.908 (1909). Whitby, G.S., and Crozier, R. N., Can. J. Research, 6, 203 (1932).
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