SEPTEMBER. 1939
INDUSTRIAL AND ENGINEERING CHEMISTRY
have been present in the solvent drops nrriving at the top. In using the ketone a correction was made for thesmall acid cuncentration of the water phase in the tower, hut with benzene this correction was quite negligible. In both cases the water in the bower wm changed after eheh run. Total material balances cheeked within 2 w r cent in all tests. method described helow for the samples from (he pncked col'kn. aqueous nroducts were obtained from the buret readinas. The
B stbp
1145
or lowered as desired. The elevation of this overflow determined the position of the interface between phases in the tower, which could he controlled easily in this way. This overflow device in the raffinate line is indicated in Figure 1. Both feed liquids were pumped continuously from storage vessels at floor level to head boxes situated on a platform ahout 14 feet above the floor. The feed to the column was by gravity from these constant-head supply vessels, tho overflow in each case heing returned to the storage vessels. Calibrated orifices were inserted in each feed line, as Figure 1 indicates, and fitted with petcocks to remove air from the manometer leads. Dyed butyl phthalate was used as 5 manometer fluid. Glass carboys were used for aeid storage, with a copper head box and 0.59-inch glass lines. Steel drums were used for the solvent, with a/&ch iron pipe lines.
watch on smale drops
effective height of the column was v a h d irom'i.0 to 57.7 inches by adjusting the position of the lower stopper carrying the nozzle. .4ll runs were made at 22-28" C. (71.6-82.4" F.).
Packed Tower Solvent m d aqueous streams were contacted in a 3.55-inch i. d.
Pyrex glass tower, 6F inches long and mounted vertically. This was fitted with headers and distributing nozzles at both ends and operated empty as a spray tower or acked with one of three
FlOURE 2. BRASS HEanEH packing materials. In addition to %e tower, the necessary auxiliaries included storage vessels, feed and product lines, orifice meters, pumps, and an overfloow device to control the interface The solvent extract was stripped of acid for re-use by contactin between the two phases in the tower (Figure 1). with water or with a dilute solution of sodium hvdroxide. Acii In all runs the direct.ion of diffusion was from aqueous laver to solvent layer-i. e., an squeous solution, initially6.0 per cent acetic acid, was extracted by either benzene or methyl isobutyl ketone. laver. ~ either or raffinate. ~~.The - amwm~s~ .~ "feed~ ~ , will be referred to as acid. Since the flow oi one phaso past the other is keDt in the solvent drum. Snce th&dves& &re anrbted bv necessarily by gravity, the heavier acid phase entered the tower at the top and was withdrawn a t the bottom, while the solvent passed in the reverse direction. head boxes for annroximatelv'one hour in order to saturat; each At each end of the glass tower was a brass header consisting of a cylindrical chamber 3 inches hi h and 3.5 inches i. d. The incomin liquid was fed into tho d e of the chamber whence it entered &c tower through six 0.120-inch i. d. brass tubes extending .~~~ 2 inches into the tower and 2 inches into the header chamber. iusted hv meam of the overfl&contr& and theK6ws were set These were spaced s mmetrically and held at the desired rates. The a t a radius of 1 incx from the center of the tower. Tho outgoing liquid was withdrawn through a '14inch brass pipe leading from a hole bottom header, dewndina on which phase was dispersed. After ahout in the center of the header plate. One of these headers is shown in four complete changes oi the conFigure 2. The six small feed tubes tinuous nhase in the column. iudeed extend into the header chamber, sufficient' to obtain steady atate: a with the supply tube feeding the header at the right and the brass pipe through which li uid was withdrawn a t the left. Tee cover plate the flow rates. and thetestbvas enaed (shown removed) was fitted with a petcock and a glass theraometer. In most a i the runs with packing the packed height was 54 inches, with &inches free spaco above and helow the packing. The packing rested on a a/s-inch-mesh nickel vire grid. In a few runs only 20 inches of packing were used, with the free space above the packing increased to 40 inches. In order to avoid the occurrence of appreciable extraction in the large cat&& used a i d tge mixture was free space above the packing in these shaken violently until the end point tests, the six upper ired tubes were ws6 reached. extended by 0.24-inch glass tubing to A faint blue in the water layer was introduce the acid a short distance taken as an end point. As a check A wood spacer above the paekin it was found tKat the Fame end maintained the &ss extensions in point was obtained when sufficient the snme rclati;e position as the ethvl alcohol was added to make short brass tubes previously dethe" two phases completely miscible. scribed. The ketoneextrsct wss titrated in s PUMP PUMP The aqueous raffinate leaving the similar manner with 1 N caustic. column passed from the bottom The benzene feed was titrated with header through a svivel pip0 to an 0.01 N caustic; the ketone feed with overtlois- vcssd which rould be raised FIOURE 1. DIAGRAM OF APPARATUS 0.1 N caustic. ~
~
~
~~~
INDUSTRIAL AND ENGINEERING CHEMISTRY
SEPTEMBER, 1939
1119
FIGURE 1. VISCOSITY-NITROCELLULOSE CONTENT CURVES A.
B.
100 parts solvent (undiluted) C. 60:40 toluene dilution 80:ZO toluene dilution D . 50:50 toluene dilution E. 40:60 toluene dilution
1. Ethyl aoetate (90%) 2. Ethyl propionate (90%) 3. Isobutyl acetate (90%) 4. n-Butyl acetate (90%)
Isobutyl acetate (10% n-BuOH) 6. Isobutyl propionate (87%) 7. Isobutyl propionate (99%) 8. Pentacetate (87%)
5.
posed of curves for the eight ester compositions undiluted and at a toluene dilution of 80:20, 60:40, 50:50 and 40:60, respectively. The weights of nitrocellulose used were such t h a t the resulting viscosity values and the curves which they yield cover a range of 40 to 70 seconds. This includes the complete range of spraying viscosity from the point of very fluid, low solids compositions up to the point where the solution is approaching a viscosity which would not be practical with the ordinary spraying technique. The curves for the solvencies of n-butyl acetate, isobutyl 10 per cent n-butanol for acetate, and isobutyl acetate nitrocellulose coincide almost completely throughout the
+
Data obtained by the use of the constant viscosity procedure for nitrocellulose solvent evaluation are presented for eight solvent mixtures throughout the complete range of toluene dilution and of practical spraying viscosity. These data may be used for a rapid calculation of the relative values for solvent strength of the mixture a t any desired viscosity. The data demonstrate that nbutyl acetate and isobutyl acetate possess essentially the same nitrocellulose solvency characteristics with toluene as the diluent. The excellent solvent strength of ethyl propionate for nitrocellulose is pointed out, and its advantageous position between ethyl acetate and the butyl acetates is shown. The great inflaence of increased alcohol content on the solvent strength of isobutyl propionate is demonstrated.
90
entire range of toluene dilution (Figure 1, A , B, C). Any difference between the three materials is insignificant until a dilution of 50 per cent (D) is reached. At 60 per cent dilution ( E ) the differences have become somewhat more obvious, with the isobutyl acetate-n-butanol mixture showing a slight advantage. This indicates that a t least in the case of the butyl acetates the isoester is susceptible t o greater activation with a suitable alcohol than the normal ester. Although ethyl propionate has an evaporation rate roughly midway between ethyl acetate and the butyl acetates, Figure 1A shows that its solvent strength approaches t h a t of the butyl acetates in the undiluted mixtures. This relation holds until a toluene content of around 40 per cent (C) is
00
70 60 50 40
6
7
e
9
IO
CRAMS NITROCELLULOSE PER IOOcc. BASE LACWER
II
1120
INDUSTRIAL AND ENGINEERING CHEMISTRY
VOL. 31, NO. 9
FIGURE 2. SOLVENT COMPOSITION-NITROCELLULOSE CONTENT CURVES A. B. 1. 2. 3. 4.
40-second viscosity 50-second viscosity
Ethyl acetate (90%) Ethyl propionate (90%) Isobutyl acetate (90%) n-ButyI acetate (90%)
C. D. 5. 6. 7. 8.
60-second viscosity 70-second viscosity
Isobutyl acetate (10% n-BuOH) Isobutyl propionate (87%) Isobutyl propionate (99%) Pentacetate (87%)
tions of isobutyl propionate with isobutanol. With Pentacetate (Figure 1A) of 87 per cent ester content as the reference material, both concentrations of isobutyl propionate possess a better solvent action than the Pentacetate in the undiluted condition. This relation still maintains a t 20 per cent dilution ( B ) although the curve for the 99 per cent ester lies much closer to that of the Pentacetate and both are considerably removed from the 87 per cent isobutyl propionate. Further dilution to 40 per cent toluene (C) brings out an appreciable difference in the curves for the three mixtures ; here the 99 per cent isobutyl propionate has a much lower solvency than the Pentacetate, while that of the 87 per cent isobutyl propionate is better to about the same degree. Figure 1D for 50:50 dilution shows the comparative loss in solvent strength of the 99 per cent ester to be still more pronounced, while that of the propionate with the lower ester content now lies midway between Pentacetate and the butyl acetates. TABLE 11. SOLVENT COMPOSITION-NITROCELLULOSE CONTENT AT VARIOUS TOLUENE DILUTIONS AND VISCOSITIES Solvent: Toluene Ratio
1oo:o SO 120 60 40
50 150
40160
...
1oo:o
...
80l20
... ...
60 I 40
io150
...
40 I60
...
...
1oo:o
...
80 I20 ... 60 40
reached. Dilutions of 40 and 50 per cent are of greatest practical interest, and a t these two points (see also D) the solvent strength of ethyl propionate is closer to that of ethyl acetate than it is to the butyl acetates. For the lacquer formulator who desires a somewhat slower evaporating and a more blush-resistant solvent than ethyl acetate and the lower ketones, and a t the same time must maintain a high solids content and high hydrocarbon dilution, the use of ethyl propionate offers interesting possibilities. That the inclusion in the lacquer formula of relatively large amounts of alcohol, within the desired evaporation rate range, has decided advantages from the economic standpoint is demonstrated-by the data and curves for the two concentra-
...
50 I50
Solvent Comuosition Ethyl acetate Ethyl propionate Ethyl acetate Ethyl propionate Ethyl acetate Ethyl propionate Ethyl acetate Ethyl propionate Ethyl acetate Ethyl propionate Isobutyl acetate n-Butyl acetate (90 Isobutyl acetate Isobutyl acetate n-Butyl acetate Isobutyl acetate Isobutyl acetate n-Butyl acetate Isobutyl acetate Isobutyl acetate n-Butyl acetate Isobutyl acetate Isobutyl acetate n-Butyl acetate Isobutyl acetate Isobutyl propionate Isobutyl propionate Pentacetate Isobutyl propionate Isobutyl propionate Pentacetate Isobutyl propionate Isobutyl propionate Pentacetate
...
... a
Crams Nitrocellulose/lOO Cc. Base Lacquer 50 60 70 sec. sec. Ban. _.._ 9.3 10.9 12.1 13.0 8.8 9.9 11.2 10.8 9.0 10.6 12.3 11.6 9.8 8.7 11.2 10.4 10.0 8.7 10.8 11.4 8.1 9.2 10.0 10.6 9.4 8.2 10.2 10.9 8.7 7.7 10.1 9.5 7.7 10.2 8.8 9.6 7.0 7.9 9.0 8.5 7.8 8.8 10.0 9.4 7.8 9.5 8.8 10.1 7.8 9.4 10.2 8.8 7.8 9.2 8.7 9.8 7.8 9.3 8.7 9.9 7.8 9.3 8.7 9.8 7.2 8.1 9.4 8.8 7.2 8.2 9.5 8.9 7.3 8.2 9.5 8,9 7.1 7.8 8.9 8.4 7.0 7.9 9.0 8.5 7.2 8.0 9.1 8.6 6.3 7.3 8.1 7.8 6.4 7.3 7.9 8.3 23.5 6.6 7.4 8.0 .~ 9.3 7.0 8.0 8.8 9.2 6.9 8.0 8.6 9.1 7.0 7.8 8.6 9.3 7.0 8.0 8.7 8.9 7.7 6.8 8.4 7.0 8.8 8.3 7.7 6.8 8.9 8.4 7.7 6.3 7.1 8.1 7.7 6.6 8 . 0 8.5 7.4 6.4 8.5 7.4 8.0 7.4 6.6 5.7 7.1 6.2 8.1 7.1 7.7
82..
~~
Viscosity in No. 7 cup a t 25' C.
Solubility Table I1 shows the solubility values of the esters a t four standard viscosity points for the various dilutions as derived from Figure 1. These nitrocellulose content values are plotted against per cent solvent in the volatiles for the four standard viscosities in Figure 2. From these curves there
SEPTEMBER, 1939
INDUSTRIAL AND ENGINEERING CHEMISTRY
may be obtained the grams of nitrocellulose which will dissolve in any solvent-toluene mixture t o form 100 cc. of base lacquer a t any given viscosity within the determined range. Figure 2A shows the relations as they exist a t the low solids content corresponding to a viscosity of 40 seconds, B shows the conditions existing a t 50-second viscosity, and C those a t 60 seconds. Finally, on the high solids side of the viscosity range, D shows the relations a t 70 seconds. The influence of the solids content upon the slope and relative positions of the curves for the various esters is illustrated most strikingly by a comparison of A and D. From Figure 1, curves for any viscosity within the given range other than those shown may be established. With these curves it becomes a simple matter t o calculate the relative value of the solvent strengths of the solvents a t any desired viscosity. The method was covered in detail in the preceding paper (2) and consists in assigning a cost value to the solvents and to the diluent, calculating on this basis the costs of the amount of several different solvent-toluene mixtures necessary t o dissolve 100 grams of nitrocellulose with each of the eight solvents. Curves are drawn for solvent and diluent cost against nitrocellulose content, and from these curves the mixture of minimum cost for each solvent is determined. At this point the mixture of minimum cost for any one of the eight solvents may be chosen as a standard, and the values of the other solvents a t the same nitrocellulose content calculated accordingly; to make the evaluation still more complete, the value of each solvent may be calculated on the basis of the most economical mixture of all the other solvents. Obviously, the comparison of the cost values is of greatest practical use with solvents or solvent mixtures which have
1121
comparable evaporation rates and similar film-laying characteristics, or in cases where a change of these properties in one direction or the other is definitely desirable. The CVP has been used to evaluate, in addition to the esters covered in this paper, other acetates and propionates, several ketones, ether-alcohols, and miscellaneous solvents. Although toluene is the only hydrocarbon for which data have been presented, other commonly used diluents have been compared in formulas containing the solvents described here. Several commercially used petroleum hydrocarbons of both the aromatic and aliphatic types have been included. Lack of space prevents a complete description of these data, and the results will be reported in future communications. Dry nitrocotton has been used in the evaluations summarized above to conform with usual practice. However, comparable data are being obtained with commercial, alcohol-wet nitrocellulose. Further studies now under way demonstrate the utility of the CVP, not only for measuring the activating effect of various alcohols, but also for comparing in a practical way the influence of alcohol concentration on solvent activation. These investigations confirm the wide applicability of the constant viscosity procedure and will be described later with the other applications of this method.
Literature Cited (1) Gardner, H. A., “Physical and Chemical Examinations of Paints, Varnishes, Lacquers and Colors,” 8th ed., p. 585
(1937).
(2) Ware and Teeters, IND. ENQ.CHEM.,31, 738 (1939). PR~SH~NTIUD before the Division of Paint and Varnish Chemistry at the 96th Meeting of the American Chemical Society, Milwaukee, Wis.
Acidic Constituents of Bone Oil MAX F. ROY AND GEORGE HOLMES RICHTER The Rice Institute, Houston, Texas
A
LTHOUGH numerous studies have been made of the basic and indifferent portions of bone oil, there has been little mention of the acidic compounds present other than the reported isolation of phenol by Weidel and Ciamician (3). The purpose of this study was to investigate further the constituents of the acid fraction of bone oil. I n so far as possible the methods of modern qualitative organic analysis were followed in which the oil was treated as a very complex mixture. Preliminary experiments showed that extraction with immiscible solvents was impractical owing to the troublesome emulsions that formed. Therefore the crude oil was purified somewhat by the removal of the nonvolatile matter by distillation. This distilled oil was extracted with water, dilute acid, and dilute alkali. I n this manner the constituents of the distillate were separated into the following groups: watersoluble compounds, 7.7 per cent by weight; organic bases, 22.6; organic acids, 2.9; indifferent compounds (i. e., substances not appreciably soluble in water and neither basic nor acidic), 66.8. The acidic fraction was found to contain phenol, o-cresol, m-cresol, p-cresol, 1,3,5-xylenol, and probably 1,4,3-xylenol. Some pyrrole was also found in this fraction; its presence was due to its solubility in water.
Sixty liters (51.2 kg.) of the crude oil were distilled to give 48 liters (41.5 kg.) of a clear yellow-brown oil and a water layer of 1.5 liters. The temperatures of distillation ranged from 80’ to 270 O C. The residue was a black viscous tar which solidified on cooling. During the distillation small quantities of a white solid material collected in the condenser; it consisted of ammonium carbonate with smaller amounts of ammonium sulfide and cyanide. Four-liter portions of the distilled oil were extracted six times with 1-liter portions of water. In this operation the weight of the oil diminished 3.2 kg. or 7.7 per cent. Four-liter portions of the oil thus extracted were again extracted with 1-liter portions of 5 er cent hydrochloric acid until the extract was acid to Congo Reland then washed once with 0.5 liter of water. The weight of the oil decreased 9.4 kg , which indicated 22.6 per cent of organic bases. Four-liter portions of the remaining oil were then extracted with 1 liter of 5 per cent sodium hydroxide solution which was sufficient t o remove all the organic acids. The loss in the weight of the oil was 1.2 kg., representing 2.9 per cent of acidic constituents. After being washed with water, the residue from the extractions weighed 27.7 kg. This represents 66.8 per cent of indifferent compounds.
Isolation of Acidic Constituents The alkaline extract was acidified with sulfuric acid and extracted with ether. The removal of the ether left a residue of 847 grams of crude acidic compounds, which was then put
