January, 1933
INDUSTRIAL AND ENGINEERING
containing plaster of Paris came to constant weight was taken to indicate some decomposition of calcium sulfate to the oxide. It is of interest to note that a previous worker in this laboratory obtained a loss on ignition of 22.5 per cent on a sample having the composition represented by curve 1, which had been in a safe 18 years. There was no apparent shrinkage in the volume of the specimens which had been in the tubes 3 years. Although some of the mixtures studied have been used in filling the steel shells of fireproof safes, it seems probable, because of the different conditions prevailing, that the results obtained cannot be considered as indicating closely how such insulators attain atmospheric equilibrium in a safe. The data presented seem to justify the following statements as legitimate conclusions to be drawn from this work:
CHEMISTRY
9.5
1. There was a relatively large loss of weight in all cases over a period exceeding 2.5 years. 2. The percentage loss was distinctly different for the different combinations, being largest in the combination containing Sil-0-Cel. 3. The continued upward trend of the curves indicates a probable further loss of weight. 4. The loss on ignition was different for the different comhinations, but in no case was it as low as that obtained for a sample taken from a safe 18 years old.
LITERATURE ClTED (1) Alley, Eng. Mtning J. Press, 120, 872 (1926). (2) Anonymous, Chem. & M e t . Eng., 31, 972 (1924). (3) Hull, Bur. Standards, Tech. Paper 130, 4, 20 (1919). RECEIYED June 15, 1932
Component Distribution Trend in Commercial Turpentine Still Operation S. PALKIN, Industrial Farm Products Division, Bureau of Chemistry and Soils, Washington, D. C. It is not unreasonable to assume, in view of the large size camphor, terpin hydrate, and a-terpineol, preliminary of the field distillation apparatus, that rectification takes place fractionation of the turpentine (the initial material) has to a limited extent, tending to concentrate the tailings and often been found advantageous (1, 4). Not only may the also the P-pinene toward the end of the run. A study of component distribution of commercial fieldeffect of the “tailings” constituents be thus minimized, but fractions of higher /3-pinene concentration may also serve turpentine distillation under normal conditions was therefore more advantageously in certain special processes ( 2 ) in which undertaken to determine to what extent rectification takes place and to obtain data for ascertaining the practicability of this terpene is the active component. A portion of the tailings mixture may be regarded as arising dividing the product of distillation into several parts, each of through oxidation, polymerization, etc., of the turpentine, and which may serve as a better raw material for certain purposes probably also through frothing and spattering of the rosin than the whole turpentine. Since this procedure can probablv be followed without during distilling. The ch”ange in field equipmajor portion in fresh e: b + m e n t a n d since i t turpentine, h o w e v e r , o% r e q u i r e s little or no occurs originally in the e x t r a l a b o r , it may gum and includes the h a v e s o m e economic a r o m a t i c derivatives advantages. w h i c h contribute the agreeable characteristic Examination of two odor to gum turpencommercial runs in this tine. investigation has demonstrated t h a t , a l Centralized p l a n t s , though rectification ocwell equipped with fraccurs to a limited detionating towers, etc., are generally available g r e e , nevertheless a in industries where turturpentine of h i g h e r D e n t i n e constitutes a SLASH PINE pinene and lower tailLONGLEAF PINE by-product, as in the FIGURE 1. DISTILLkTION CHARTS FOR COMMERCIAL RUNS ings content than that manufacture of paper of the whole turpentine pulp or where it is one of a number of major products, such is procurable by taking early cuts a t appropriate points in as in steam and solvent extraction or destructive distillation of the distillation. pine and other woods. I n these the turpentines represent EXPERIMESTAL PROCEDURE arbitrarily set cuts in the distillation. Gum turpentining, however, is carried out by a large nuniAs the t x o species Pinus palustris (long-leaf pine) and ber of producers directly in the field, in the main with simple Pinus caribaea 31. (slash pine) constitute the sources from fire stills under conditions where the use of elaborate engineer- which practically all American gum spirits of turpentine are ing equipment is economically impracticable. These stills are obtained commercially (9), two sets of authentic samples, generally quite large, about 10 feet in height (to top of neck), representing these sources, were taken from runs made in a and 8 feet across. They have a capacity of about 10 barrels commercial still. Each set comprised three samples repreof gum per charge (about 51 gallons per barrel). sentative of the three cuts of the distillate. Sample 1 con-
I
N PROCESSES such as the manufacture of synthetic
~
I N D U S T R I A L A N D E N G I N E E R I S G C H E R.1 I S T R Y
96
sisted of 51 gallons taken after the first 5 gallons a t the beginning of the distillation had been run into a separate container; sample 2 represents the following 51 gallons; and sample 3 the last 18 gallons (long-leaf only). The gum of each charge was mixed as well as the limited facilities permitted. As there is no provision in the field stills for running total reflux, it was thought that postponement of sampling until after the first 5 gallons of distillate came over might allow sufficient time for the steam agitation to effect a thorough mixing of the large charges of gum involved. This, however, was not entirely accomplished as will be seen later. Distillation charts for the respective runs are shown in Figure 1. 15 MM.
8 MM. DIMENSIONS ARE INTERNAL
Vol. 23, No. 1
and modifications of the thermal insulation, is similar to that described previously (8). Pressure in the system was maintained constant by means of a short inclined mercury regulator and relay, shown in Figure 2A. Virtually all the distillations were carried out a t 20 mm. or less. The short manometer regulator was found to be very effective for the purpose, both on account of the low resistance t o mercury movement and increased sensitivity resulting from inclination of the contact arm. Figure 2A also shows the relationship of the pressure control system to the column assembly proper. This assembly was in its general plan, including the plate column (twenty plates and about 120 cc. in height), like the large one. I n view of the absence in the literature of mention of microplate columns suitable for fractionation in vacuum-that is, with low holdup and of sufficiently large capacity t o handle comparatively large volumes of vapors incident to low-pressure operation-detailed measurements of this column are given (Figure 2B). The trap tubes contained only 0.3 cc. of liquid each, when primed. Optical rotation measurements were made in the yellow (578 mp) and in the green (546 mp) by means of a Schmidt and Hansch polarimeter equipped with a spectroscope. Rotatory dispersion values so obtained are of particularly diagnostic significance ( I O ) . After complete fractionation of each of the samples examined, the top three or four fractions (representing the highest concentration of a-pinene in each case) were further purified by refractionation. (Constancy of rotation for this terpene from each of the respective samples was attained practically after one refractionation, as shown in Table I.) DATAo s CY-PINENE COMPOSENTS OF TABLEI. ROTATION TURPEXTIXE SAMPLESQ
-
(Observed rotation in 10-em. tube, in degrees)
S~XPLE
LOFQ-LEAF
Yellowb P R
AI
+13.09 +13.04 f12.84 +12.00
3 4
FIGURE2. FRACTIONATING ASSEMBLY Arrangement for pressure control Detail of small column
LABORATORY DISTILLATIONS. The samples were fractionally distilled a t reduced pressure and the respective fractions examined for rotation, refractive index, and density, as described previously (8). From 1000 to 1500 grams of sample constituted the charge, and all but the last 50 to 100 grams were fractionated a t 20 mm. in the large apparatus. The remaining 50 to 100 grams were then completely distilled a t lower pressure (3 or 4 mm.), leaving only the rosin, etc. Fractionation of the charge was then completed in the small apparatus (Figure 2B shows the column detail). These fractions were also examined for rotation, refractive index, etc. For purposes of calculation and to provide more accurate optical data on the tailings constituents, these fractions were refractionated. The respective proportions of a- and /3pinene and tailings were then determined by the optical method of Darmois and Dupont (IO) as described previously (8).
EQUIPMENT. The fractionating apparatus used comprised the following: large fractionating assembly with a wire-gauze plate rectifying column (thirty-two plates, 5 cm. inside diameter, 200 cm. in height), which is an improved form of this type of column described earlier (7). The rest of the assembly, with the exception of the pressure control system
= FIRST 4 F R A C TIOh'S FROM .4
1 2
A. B.
GreenC f14.84 +14.79 +14.49 $13.53
Yellow
B i = FIRST 3 FRACTIOh-S FROM B
Cl
f14.62 +13.85 +11.15 5.29
B2
1-13.60 +13.67 $13.75 f13.60 $13.56 +13.15
+16.97 +17.73 +17.63 +17.65 +17.80 +17.65
A3
= REFRhCTION.4TION O F A2
+13.75 +13.67 $13.80 f13.75 +13.80 $13.78 +13.78 +13.73 +12.98
$15.45 +15.40 +15.52 +15.57 +15.55 +15.53 +15.53 +15.53 +15.69
B3
= FIRST 4 FRACTI016 FROM A
1
-27.81 -27.81 -27.56 -26.61
2
3 4
A?
-31.31 -31.31 -31.14 -29.81
=
REFRACTIOFAT I O N O F A1
+19.15 +19.05 1-18.70
REFRACTIOIAT I O N OF B1
3
$18.95 1-20.0 +20.0 +19.99 +20.05 +20.0
=
REFRACTIONhT I O S OF BP
f17.88 +17.70 +17.70 +17.85 +17.80 +17.85 +17.82 +17.67
-SLASH hi
7
Yellow
$16.93 +16.86 f16.38
A 2 = REFRACTIONAT I O N OF A1
+15.37 +16.45 +15.47 $15.45 +15.26 1-14.87
PINE
Green
+20.20 +20.00 +20.05 +20.14 $20.10 +20.20 +20.13 $20.00
-27.70 -28.18 -28.18 -28.20
-31.19 -31.86 -31.95 -31.75
BZ = R E F R I C T I O N A TIOK OF B1
FIRST 4 FR4CTIONS F R O V C
+
+16.55 $15.75 $12.75 6.30
+
C% = REFRACTIONA$ 1 5 T. 9I O 6 N OF+16.02 C1
+16.00 +16.25 +16.92 +15.77 +15.65 C3
Ci
REFRACTIONAT I O N OF C2
f18.00 f18.05 Jr18.07 f18.20 +18.06 +17.58
= F I R S T I FRACT I O N S FROM C
-28.18 -28.21 -27.98 -26.96 CZ
+18.05 +18.31 f17.90 +17.85 +17.65
=
$16.00 C16.01 $16.01 +16.15 f15.95 1-15.57
PISE-
B1 = F I R S T 4 F R A C T I O N 0 FROM B
Green
-31.78 -31.81 -31.48 -30.16
=
REFRACTIOS.4T I O N OF C1
-28.31 -31.96 -32.01 -28.21 -28.42 -32.15 -32.01 -28.31 -28.31 -31.96 -28.50 -32.21 -28.59 -32.36 -32.11 -28.51 4 -32.37 -32.31 -28.71 -28.71 -25.76 -28.61 -27.96 -25.22 Sample takqn from 51 gallons of distillate collected at beginning of a A run (first 5 gallons distillate taken in another,vessel). R Sample gallons of of distlllate collected. B -. Samnle . . . =. .taken from next 51 aallons remaind& of distillate collected. C :. Sample taken from remainder A B and C were each fractionally distilled in the laboratory. The first thrie 0; four fractipns of each (designated under A, B, C,, respectively) were refractionated, giving a sene8 of fractlons. The first SIX or four fractions of these (designated under A*, Bz, Cz, res,pectively) were again refractlonated (in case of long-leaf pine). giving the series under 8 3 , B3, Cs. B 578 mp. C 546 mp. 1
-27.86
2 3
-27.86 -27.96 -26.21
-I
-31.51 -31.51 -31.66 -29.35
N E 15 11 1 N G C H E M 1 S T 11 Y
...
distn.6
...
IA*i 15% Oi distn
58
3'1
2.7
5tI.B
43.7
3.6
.... .
.
. .
. . . . . . .
.., .
. . . . . . . . .
97
By clmging tlie recciviiig vessel iit L. siiiiilar point iii dist,illing the slasli pine (in ~vliicli the tailings content of tire ivlioie turpentine is 4.i5 per cent), a pcoiiminced improrenrelrt iri tailings freedom is effected, the first 85 per cent sliowing ari average of 2.4 per cent less tailings than the last 15 per cent. Considerable difference is evident in the rectifying tendency of the two runs, particularly wlien the first 51-gallon disre compared. In view of tlic many variable factors involved, greater urriSoriiiity in distribution data is hardly to be expected. Tile data obtuiried in these experiments, altiiougli only approximately indicative of the general rcetifyirig tendency prevailing under normal conditions in the fire still, slrow t h a t both tailings arid @-pinenetend to conceentratr perceptibly in the last 15 per cent of the run. Thus tire proportion of p-piiiene in tlie lnst 18 gallons or so OS distillate was higher tlia.ri that in the whole turpentine by fito 8 per cent. Conversely, fractions from 2 to 6 per cent liiglicr in a-pinene comtent and ahout 0.4 to 1 per cent lower in tailings cont.cnt were obtained by taking the first 51 galloris OF distillate, than if tlie wlrole turpentine were takm. The improverrient etkcted with regard to tailings, wide app:xently not great, is niore significant than the absoliitc fignres would indicate (4). Tlie t,orpentines iirre considered acre of exceedingly good quality, particularly the long-leaf, :in11 the tailings content %wasless tiinii that ordinarily folirid in T ~ 8~ )~. turpwtiiie of ~ ~ I I I I I I C(6, hcKsl,\\-l.sua\l
,1 \tic: wiiples turpentine fmni the t w species of pine isere t,ukeii Srmi runs tirade irr a comniercid still, and were d h i i i e d irmn I). F'. €Inwcl1 of Olust,ree, Fla., throllRIl the kind ci~tiperatioiiof C. 1'. S l d i of the Pine Institute of Aini~im. 1)rawings were inatie by R. N. Raker- of the
I'resuni~rbly, coiiiplete and tlioroiigli niixiiig OS tlic gun1 \vouId have yielded an a-pinene of usdorm optical value for a l l three of the siilisani~~ler froni my oiie complete charge. As may be obserred from Table I, this wtis nearly accoinplislied in the case of tile slash pine. Appreciahlc difference, however, was noted iu the case of t,hc long-leaf pine. Suoli differences in rotatiiin can hardly be ascribed to the presence OS iii~npinene coitstituents, such as the low-boiling hydrovarhoiu obtained by C'li:Lmnnes (3) oii fractionating I'rcnel, turpentine, since tlie rotations
