MAY, 1937
INDUSTRIAL AND ENGINEERING CHEMISTRY
c. The pigments which are suspended in nonpolar compounds exhibit a simultaneous positive and negative charge. d. Mixed pigments may exhibit a charge different from that exhibited by the individual pigments when suspended in a polar-nonpolar medium.
2. When mixed pigments exhibit either a positive or a negative charge in a polar-nonpolar medium, they will disperse when the mixture is diluted with mineral spirits. 3. Mixed pigments which exhibit a simultaneous positive and negative charge in a nonpolar medium, flocculate when the mixture is diluted with mineral spirits. 4. Flooding of the pigment of smaller particle size is present when the mixed pigments, while suspended in a polar-nonpolar medium, exhibit either a positive or a negative charge. 5. With pigments that disperse, flooding occurs with the pigment of the smaller particle size. 6. Mixed pigments which exhibit a simultaneous positive
571
and negative charge in a nonpolar medium, do not flood, regardless of the variation in the range of the particle sizes of the pigments. 7. Flooding is not present if the pigment is flocculated.
Acknowledgment The author takes pleasure in expressing his appreciation to J. J. Rankin and associates on the technical staff of the St. Joseph Lead Company for their helpful suggestions and criticisms during the preparation of this manuscript.
Literature Cited (1) Edelstein, Edwin, Am. Paint J . , 17, No. 53A, 11 et seq. (1933). (2) Ladd, E. V., Ibid., 15, No. 51E, 13-14 (1931).
RECEIVED September 14, 1936. Presented before the Division of Paint and Varnish Chemistry at the 92nd Meeting of the American Chemioal Society, Pittsburgh, Pa., September 7 to 11, 1936.
Fractional Distillation of Cracked and Polymer Gasolines A cracked and a polymer gasoline were fractionated in a hundred-plate column. Unlike the polymer gasoline, the cracked gasoline fractionates similarly to a Bradford straight-run gasoline as far as the general shape of the refractive index curve is concerned. The division of the cracked gasoline into molecular size approximates that of the straight-run gasoline. This is not true of the polymer gasoline. Blends of the polymer gasoline varied in octane number from 72 to 82 ; blends of the cracked gasoline varied from below 41 to 75.
T
HIS laboratory fractionated various straight-run gaso-
lines in efficient distillation columns and found marked differences in chemical composition (IO). At the same time certain fractions of particular value were obtained. Similar distillations of cracked and polymer gasolines should yield information regarding their composition and fractions with different properties and uses from those obtained from straight-run gasoline. Accordingly, a polymer and a cracked gasoline were fractionated. Ipatieff and co-workers hqd previously studied polymer gasoline (I, 4, 6). The polymer gasoline was obtained from the Universal Oil Products Company. This gasoline was produced commercially from a stabilizing unit for cracked gasoline, with a capacity of 3,000,000 cubic feet of cracked gas per day. The olefin content of the cracked gas was 25 per cent propene and butenes. The gas, under a pressure of 200 pounds per square inch and a temperature of about 232" C. (450" F.), was passed over solid phosphoric acid catalyst in a series of four
C. 0. TONGBERG, J. E. NICKELS, S. LAWROSKI, AND M. R. FENSKE The Pennsylvania State College, State College, Pa.
reaction chambers. The yield of polymer gasoline was 4.3 gallons per 1000 cubic feet of gas, which represents about 85 per cent of the propene-butenes present in the gas. The cracked gasoline was obtained from the Kendall Refining Company, Bradford, Pa. It was the product of a two-coil selective Dubbs cracking unit, where the feed was 20 per cent kerosene, 10 per cent foots oil and slack wax, and 70 per cent gas oil, all of Pennsylvania origin. The unit was processing about 1550 barrels per day, t o give a 74 per cent gasoline yield in a nonresidue or coking type operation. The No. 1 furnace coil operated a t 499OC. (930" F.) and 450 pounds per square inch pressure; the No. 2 furnace was run at 529" C . (985" F.) and 475 pounds per square inch pressure. The properties of these two gasolines are given below; for purposes of comparison a straight-run Bradford gasoline is included. A. 9. T. M. Engler Distn. Initial b. p. 30% 40% 50% 60% %
;;
90% End point Gravity 'A. P. I. Octane hro. C. F.R. motor method
-Cracked-
' C.
F. 86 129 164 201 236 268
30 54 73 94 113 131 152 306 171 339 189 372 208 406 219 426 58.3 66
-Polymer-
-Straight-RunC. O F. 58 136 40 104 85 185 158 70 91 87 196 188 95 102 203 215 99 211 113 236 218 126 103 258 136 108 227 277 243 309 154 117 275 337 169 135 328 370 188 164 220 428 210 410 66.2 62.3
C.
81
O
F.
42
The distillations were run in a 0.95-inch i. d., 39-foot column with approximately one hundred theoretical plates when
INDUSTRIAL AND ENGINEERING CHEMISTRY
572
TABLEI. BROMINE NUMBER OF HYDROCARBONS No.-
-Bromine Carbon No. of Atoms
Compound
B. P.
7 8 7 7 8 8 9 10 8 7 7 13 12 8 8 9 10
Error
%
80.1 98.4 99.3 100.8 110.6 136.1 139 169.2 177.0 102.9 98.9 90-92 96
6
0
0
0
....
0
0 0 0 0 0 0 0 143
o
.... ....
1 4 0 172
+20.3
163 88 95 143 143 127 113
186 95 123 152 124 132 134
+14.1 7.9 t29.5 + 6.3 -13.3 3.9 f18.6
0
.. .. .. ..
it$ it:
. . . . . .. .
179.9 117-119 119 142-144 57-59 (15 mm.)
$ g:! + +
TABLE11. COMPARISON OF GASOLINE FRACTIONS~ -Cracked-Hydrocarbons of Similar B. P. Cyclopentane n-Hexane Benzene-cyclohexane n-Heptane Toluene Branchedootanes n-Octane Xylenes n-Nonane 9-Carbon aromatics n-Decane 10-Carbon aromatics
-Straight-Run-B.p.
c.
5 6 08 . 68
nv
1.3760 1.3810 1.4147 9 8 . 1 1.3955 107.4 1.4380 1 1 7 . 8 1,4032 125.8 1,4028 137.8 1.4545 150.7 1.4122 162.8 1.4398 1 7 4 . 3 1.4187 184.6 1.4408 80.0
B.p.
c.
46 98 . 15 78.4 98.5 109.0 121.2 125.3 138.2 149.2 162.3 174.9 184.6
n v
Bromine NO.
--PolymerB.p. O
1.3915 1.3837 1.4250 1.3969 1.4539 1.4150 1.4188 1.4466 1.4213 1.4537 1.4339 1.4588
137 58 137 43 105 58 70 67 56 58 38 41
c.
56 18 '. 42 80.4 97.8 109.2 118.0 125.3
n?
Bromine NO. 155 212 200 191 187 181 187
1'3852 1.4007 1.4002 1.4140 1.4124 1.4193 1.4206
The fractions of cracked and straight-run gasolines compared are the main peaks and valle s in the refractive index curve. The polymer gasoline fractions ?re aimply of oorresponxing boiling point since this gasoline gave a relatively smooth refractlve index curve. Q
tested under total reflux with a mixture of n-heptane and methylcyclohexane. This column was described previously and designated as column B ( 2 ) . The charge in each distillation was 10 liters, and the average reflux ratio was 40 to 1. Each fraction of distillate corresponded to 0.6 to 1.5 per cent by volume of the charge. Boiling points were determined separately in a modified Cottrell apparatus. Bromine numbers were obtained by the method of Francis (3, 8). This method had certain disadvantages but was used in previous studies on polymer gasoline ( 6 ) , and the determinations are rapid. The two main difficulties are substitution of bromine and slow rate of addition. The former is particularly troublesome in the case of highly branched olefins such as diisobutylene and triisobutylene. This difficulty is minimized in the method described by McIlhiney (7). The bromine numbers of certain hydrocarbons, as determined by the method of Francis, are given in Table I. The results of the distillations are given in Figures 1 and 2. The cracked gasoline fractionates similarly to a Bradford straightirun gasoline as far as the general shape of the refractive index curve is concerned. The similarity is striking, and the results are unexpected. The polymer gasoline differs considerably, having no sharp breaks in the refractive index curve, and covers a rather narrow range in refractive index. Table I1 compares these two gasolines with a Bradford straight-run. The variations of the two gasolines in the boiling range for a given per cent of charge distilled are pronounced, the cracked gasoline having certain points of similarity to a Bradford straight-run as shown in Tables I11 and IV. This similarity is surprising, particularly when the refractive index is also considered; it indicates that, under
the cracking conditions u s e d , t h e c h a r g i n g stock is broken down to hydrocarbons whose division into molecular size approximates that in the straight-run g a s o 1i n e This may also indicate a possible origin of gasoline and an additional indication that the hydrocarbons of high molecular w e i g h t i n P e n n s y 1v a n i a petroleum are cyclic c o m p o u n d s with long paraffin chains. A h y d r o g e n a t i o n of this cracked gasoline and subsequent fractionation is contemplated, for it will he interesting to see if the product then contains more normal paraffins than a s t r a i g h t - r u n gasoline. I n connection with the cracked gasoline it should also be noted that there a r e c o n s i d e r a b l e amounts of 6-, 7 - , and 8-carbon-atom olefins present' Three facts in the polymer gasoline fractionation are outstanding: (1) 48.1 per cent of the original gasoline could be classified as having 7 carbon atoms; (2) bromine numbers were too high for m o n o o l e f i n s ; and (3) the refractive index curve gave no pronounced peaks and valleys. This last fact indicates that the same type of structure predominates and that the aromatic, cyclic olefin, and diolefin contents
.
Calcd. Obsvd.
c.
Benzene n-Heptane 2 2 4-Trimethylpentane MLthylcy clohexane Toluene Ethylbenzene Xylene Pseudocumene p-Cymene Diisobutylene 2Heptrpe 3-Dimethyl-2-pentene 3LEthyl-2-pentene Di-n-butylpropylethylene Triiaobutylene Olefinfrom: Dimethyl-n-amylcarbinol ' Diethyl-n-propylcarbinol Diethyl-n-butylcarbinol Diethyl-n-amylcarbinol
VOL. 29, NO. 5
The high bromine numbers a r e p r o b a b 1y due to s u b s t i t u t i o n and not to diolefins. In view of the results in Table I1 the presence of branched, reactive olefins would be expected. I n this connection it should be noted that Ipatieff (4) in p 0 1y m e lr i Z i n g a m i X t u I e Of p r o p y l e n e s and butenes found that about 50 per c e n t b o i l e d at 80Oto 110" C.; in the distillation r e p o r t e d here, about 49 per cent boiled over the same range.
3 Sa G& E? 5
7: .IS6 ~~
uI $a(~
3"'
rn
PfNTENES #FUMES
uo
--
220 IS0
Md
WLUUE PERCENT OF CHARGE DISTILLED OVER
FIQURE1. FRACTIONATION OF CRACKED GASOLINE
MAY, 1937
INDUSTRIAL AND ENGINEERING CHEMISTRY
Two very narrow boiling fractions were obtained in the fractionation of polymer gasoline as follows: Vol. Toof Charge
Boiling Range
c. 9.3 6.9
94.8-95.6 97.0-97.8
Refractive Index Range
n
Bromine
Gravity Range O A . P . I.
No. Range
so
1.4109-1.4112 1.4140-1.4152
177-182 188-195
TABLE111. FRACTIONS OF NARROW BOILINGRANQE
1-Heptene 3-Heptene 3-Ethyl-2-pentene
c.
Gravity dZQ
94.9 95.9 94.9
0.6993 0.7043 0.7172
yo of Charge-
-Vol. Straightrun
Boiling Range
c.
Cracked
1.2 2.2 4.0 3.1 4.4 1.6 7.7 4.8 4.8 2.1 4.6 3.1 4.1 4.2 4.2 3.1 1.8 2.8 5.5
65.7-66.6 64.1-64.5
Included in the second fraction were three small fractions comprising 3.1 per cent of the charge, having a boiling point of 97.7" to 97.8" C., a constant refractive index of 1.4140, a constant bromine number of 192, and varying in A. P. I. gravity by 0.3 unit. No pure hydrocarbon for which information is available has properties approaching those given. Hydrocarbons boiling similarly to the 94.8-95.6" C. fraction are (9): B. P.
573
Refractive Index
5,6
1.8
4.4 3.6 1.7 3.3 3.5 5.4 1.8 0.9 5.9 1.6 2.9 2.3 3.8 1.0 2.1 2.1 4.6
Polymer 1.7 0.6 2.5 14.1 7.9 22.0 5.0 10.0 1.8
.. .. .. .. .. .. *.
*...
..
n"D" 1.3999 1.4090 1.4120
Hydrogenation of these fractions, followed by efficient fractional distillation, would undoubtedly be a logical means for obtaining further information on the compounds actually present, particularly as to the nature of the branching in the hydrocarbon chain. Octane numbers of blends of fractions of the two gasolines are given in Table V. The polymer gasoline blends do not exhibit marked differences in octane numbers. This is
TABLEIV. DIVISIONOF GASOLINES INTO FRACTIONB OF THB SAMENUMBER OF CARBON ATOMS -Val. % of ChargeStraightrun Cracked Polymer 5.5 5.0 0.0 7.4 3.5 1.7 10.6 5.6 9.6 0 11.7 7 16.0 48.1 10.6 8 15.2 13.5 11.7 15.0 9 ... 10 10.3 12.4 ... 11 4.6 5.5 11 and higher 12:3a 20.6 11.8 7.5 Loss 7.2 17.lb a Actually this volume contains 6ome hydrocarbons of smaller number o carbon atoms that drained back into the still. b A sudden leak developed near the still when the distillate temperature reached 125.5' C. This accounts for the major part of the loss. No. of Carbon Atoms 3-4 5
TABLE V. OCTANE NUMBERS OF GASOLINE BLENDS VOl.
% of
Fractions Charge
Approx. Boiling Range a
2-8 9-14 15-19 20-22 23-25 26-28 29-32 33-35 36-39 40-44 4548 49-53 54-57
5.8 4.8 5.4 3.4 3.8 3.8 4.6 4.3 5.1 5.8 4.6 6.4 4.7 7.1 13.9 7.9 6.9 9.3 6.8 6.9 10.3
c.
Bromine No. Range
Octane No. b y C. F. R. Motor Method
60-119 105-144 45-116 91-137 95-139 36-97 42-105 83-98 66-70 67-80 46-71 52-68 38-51
75 75 65 75 63 Below 4 1 75 51 57 63 Below 4 1 69 Below 41
F.
Craoked Gasoline 29-37 84-99 39-65 102-149 67-69 153-156 72-86 162-187 89-95 192-203 97-99 207-210 101-109 214-228 114-121 237-250 124-128 255-262 132-142 270-288 146-151 295-304 154-169 309-336 172-178 342-352 Polymer Gasoline 41-75 77-85 85-91 91-95 95-96 96-97 97-98 103-116
further indication that the hydrocarbons present are of similar type. The cracked gasoline blends, however, differ in octane number considerably-the variations being similar in character t o these experienced in a straight-run gasoline. The octane numbers of those blends corresponding to the valleys in the refractive index curve are higher than the corresponding valleys in the straight-run gasoline.
Acknowledgment V O L U m E M C€N7 OF WA&€ DLWUFO OKff
FIGUF~E 2. FRACTIONATION OF POLYMER GASOLINE
The authors are indebted to Gustav Egloff of Universal Oil Products Company and to W. B. McCluer of the Kendall Refining Company for the samples of polymer and cracked gaso-
INDUSTRIAL AND ENGINEERING CHEMISTRY
574
VOL. 29, NO, 5
lines, and to W. J. Sweeney who suggested the determination of c. F. R. octane numbers and arranged with the Standard Company for their determination. The oil assistance of A. H. Mazzarola and €3. W. Thomas in the fractionations is gratefully acknowledged.
(4) Ipatieff, V. N.,Ibid., 27,1067 (1935). ( 5 ) IPatieff, N., and Corson, B. B., Ibid., 28,860 (1936). (6) Ipatieff,V.N., and Pines, H., Ibid., 28,684 (1936). (7) McIlhiney, p. C., J.Am. Chem. Sac., 21, 1084 (1899). (8) Mulliken, S. P., and Wakeman, R. L.,IND.ENG.CHEM.,Anal. Ed., 7, 59 (1935). (9) Soday, F. J., and Boord, C. E., S. Am. Chem. Soc., 55, 3293
Literature Cited
(1933). (10) Tongberg, C. O., Quiggle, D., and Fenske, M. R., IND. ENQ. CHEM.,28, 201 (1936).
(1) Egloff, G., Oil Gas S.,34, No.44,140 (1936). (2) Fenske, M.R., Tongberg. C. O., Quiggle, D., and Cryder, D. S., IND.ENQ.CHEM.,28, 644 (1936). (3) Francis, A.W., Ibid., 18,821 (1926).
v.
RECEIVED October 2, 1936. Presented before the Division of Petroleum Chemistry at the 92nd Meeting of the American Chemical Society, Pithsburgh, Pa.,September 7 to 11, 1936.
Composition of Citrus Fruit Juices JOHN A. ROBERTS Florida State Department of Agriculture, Winter Haven, Fla.
CITRUS
juice has become in recent years an important article of commerce, primarily because of its dietary value. Knowledge of the mineral content of the juice is useful for two reasons: (a) The mineral content plays an important role in its dietary value, and (6) it may furnish some clue toward better practices in grove fertilization. Data on the complete analysis of citrus juice which would show the relation of ash constituents to the other solids present in the juice are very meager. With the object of supplying these data, the work here reported was undertaken. Analytical data were obtained on the juice and on the ash of the juice. In examining the composition of the ash, chemical methods were used to determine the principle constituents, and spectrographic methods were used to determine the trace elements. Since primary interest was in fruit which was ready for market, samples were taken direct from the packing house. I n order to ensure a sample of adequate size, one-half box (0.8 bushel) was taken for analysis. The data given for each sample are not to be considered statistically representative of variety differences but concern only the sample analyzed.
LEONARD W. GADDUM University of Florida, Agricultural Experiment Station. Gainesville, Fla.
lated from total solids, and percentage of organic matter from water and ash content. All other determinations on the juice were made according to the methods of the Association of Official Agricultural Chemists. Preparation of the ash and TABLEI. DESCRIPTION OF SAMPLES ANALYZED Sample No. Variety 1 Seedling oranges 2 Blood oranges 3 Valencia oranges 4 Lue Gim Gong oranges 5 . Marsh wedless grapefruit 6 Seedy (common) grapefruit 7 Tangerines
Location of Packing Date House, Received, County 1936 Polk March Lake March Polk April Polk April Highlands April Highlands April Lake March
all chemical methods were also those of the A. 0. A. C. (Realizing the possibility of contamination of the calcium oxalate precipitates by other metals present in the ash, spectrographic examination of the ignited precipitates was made and the findings are reported here.) Analyses For the spectrographic determinations, a Littrow spectrograph with linear disEersion of about 30 inches (76 cm.) A description of the samples analyzed is given in Table I. between 2250 and 5500 A. was used. About 20 mg. of the All juice was extracted by hand in order to avoid contaminahomogenized material were volatilized in a 220-volt arc tion by metals, and precautions were taken to avoid conusing a current of 9 to 10 amperes. Electrodes of specially tamination bv the oil of the citrus rind. aurified erawhite were In analyzyng the employed. Repeated juice, c i t r i c a c i d , TABLE11. ANALYSISOF CITRUSJUICES spectra of the electotal solids (degrees Marsh trodes were made to Brix), and ratio of Seedensure control of electotal solids to citric SeedVaJen- Lue Gim less Seedy Tanling Blood cia Gong Grape- Grapegertrode impurities. In acid (maturity ratio) Analysis Orange Orange Orange Orange fruit fruit ine order to avoid fracwere determined by 1.35 1.26 1.05 0.89 1.11 0.98 0.74 Citric acid, % 1.051 1.049 1.048 1.051 1.028 1.039 1.058 tionation during volaSp. gr., 20°/20” C. methods of the Citrus 9.74 14.33 6.95 11.80 12.60 12.65 12.15 Degrees Brix t i l i z a t i o n , the arc 7.22 11.37 Fruit I n s p e c t i o n 7.81 17.09 10.96 12.04 12.00 Maturity ratio * 3.0 3.2 3.0 3.3 3.5 3.63.2 was maintained until Bureau of the Florida 87.30 87.85 88.20 87.40 93.05 90.26 85.67 Eter, % 9.33 13.93 6.73 11.39 12.20 the sample was comOrganic matter 70 12.20 11.67 State Department of 0,099 0.092 0.090 0.094 0.043 0.052 0.069 Nitrogen orgagic % p l e t e l y volatilized. 0.43 0.33 Agriculture (1). The 0.59 0.27 0.56 0.58 0.62 Protein (‘N X 6.2b), % 3.09 3.96 4.32 3.44 3.46 3.95 4.48 Reducing sugar, Yo Spectra of mixtures quinhydrone method 7.89 2.24 1.34 4.89 5.02 4.97 4.86 Sucrose % 6.20 10.98 9.21 4.78 9.34 8.48 8.92 Total &gar % containing v a r y i n g was used t o deter0.025 0.004 0.004 0.007 0.005 0.002 0.006 Pectio acid,’% proportions of t h e mine pH. Percentage 0.453 0.482 0.412 0.403 0.218 0.414 0.401 Ash, % elements served as of water was calcuY
A
