August 1948
INDUSTRIAL AND ENGINEERING CHEMISTRY
of the autoclave may function as a catalyst or more probably the malls retain traces of catalysts used in previous experiments. Previous work (10) has shown that tin sulfide alone when used with Tetralin as a vehicle has an important effect on the rate of liquefaction. The present work shows that with o-cyclohexylphenol and perhaps with most phenolic compounds such an effect is not manifest. The peculiar synergism of tin sulfide and ammonium chloride suggests that the combination is necessary to accelerate a particular kind of reaction which neither catalyst alone is effective in promoting. The hydroxylated vehicle probably solvates the coal or coal fragments and the combination of catalysts is necessary to orient the hydrogen attack. Further work on this problem is in progress. ACKNOWLEDGMENTS
The authors wish to thank George Goldbach, Margaret Wolak, and David Kusler for help with the autoclave experiments; R. A . Friedel for the spectra measurements and the gas analvses; 11. G. Pelipetz for the experiments in the glass-lined autotlave; €€, L. Smith and H. J. O’Donnell for the hand-picked samplcs of
1389
Bruceton coal; and H. 91. Cooper and Roy ,4bernathy for all the ultimate analyses except the analysis of 2-methoxy-1-cyclohexylbenzene, which was kindly performed by R. Raymond. LITERATURE CITED (1) Boudroux, Ann. chirn. (lo), 11, 556 (1929). (2) Fisher, Sprunk, Eisner, O’Donnell, Clarke, and Storoh, Bur. Mines, Tech. Paper 642 (1942). (3) Kiebler, in Lowry’s “Chemistry of Coal Utilization,” Chap. 19, New York, John Wiley & Sons, 1945. (4) Kreulen, Fuel, 24, 99 (1946). (5) Musser and Adkins, J. Am. Chem. Soc., 60, 664 (1938). (6) Orchin, Ibid., 66, 535 (1944).
(7) Orchin, M., patent pending. (8) Pauling, “Nature of the Chemical Bond,” p. 318, Ithaca, N. Y . , Cornel1 University Press, 1944. (9) Pott, A., Broche, H., Schmits, H., and Scheer, I?., GZiickuuf, 69, 903-12 (1933). (IO) Storch, Fisher, Hawk, and Eisner, Bur. Mines, Tech. Paper 654 (1943). RECEIVED April 24, 1947. Presented before the Division of Industrial and Engineering Chemistry a t the 110th Meeting of the AMERICANC H E m c A L SOCIRTY, Chicago, Ill. Published by permission of t h o Director, U. S. Bureau of Mines.
FLUORINE DISPOSAL Continuous Process RALPH LANDAU1 A N D RAPHAEL ROSEW, The Zcellex
Corporation, 233 Broudwuy, S e w k h r k , 4.Y .
Increasing industrial use of fluorine and hydrogen Huoride has caused concern regarding the disposal of gases containing even small amounts of these materials, which are toxic and unpleasant as well as destructive to crops as far away as ten miles from the source. The present paper describes a disposal plant of industrial size designed to handle large quantities of fluorine or hydrogen fluoride in varying concentrations and to remove them completely. The plant is capable of handling large quantities of pure
Huorine with relatively simple equipment as compared to previous methods. I t operates continuously, and while the excellent absorption characteristics of caustic soda ale employed in the absorber, it is continuously regenerated with lime so that the cheaper lime is consumed. Operating data on the plant are presented. The same type of plant can be employed also in handling other acidic types of gases, such as carbon dioxide, and has pqtential applications in many other directions.
I
The calcium fluoride is removed continuously from the system by gravity settling, and the caustic soda concentration is niaintained constant. Gaseous fluorocarbons and nitrogen are unabsorbed and pass out of the exit part of the system unchanged, along with traces of unabsorbed fluorine gas, when the system ia operating satisfactorily. The caustic concentration should exceed 2% ( 1 ) so that the intermediate fluorine oxide, a very toyic compound, is destroyed. The reasons for the regeneration step are: the sodium fluoride would be an objectionable contaminant and poison in the water effluent from the system; also, it has limited solubility in the caustic system and would tend to plug and erode equipment. Although the use of potassium hydroxide would reduce the second objection to a limited extent because of the greater solubility of the potassium fluoride, the cost of the potassium hydroxide R ould be appreciably higher than that of the sodium hydrouide.
N PROCESSES involving the w e of elemental fluorine for fluorination purposes, there is the problem of the removal of the residual fluorine which is usually admixed with various amounts of hydrofluoric acid, gaseous fluorocarbons, and nitrogen. Various methods that ‘have been investigated for the removal of this residual gas have been presented (1, 2 ) . This paper discusses the operation of a commercial installation which was designed and built for the removal of fluorine-containing gases involving the usc of strong caustic soda solution as the absorbent. BASIS OF PROCESS
The process is a continuous one in which the fluorine and hydrofluoric acid are absorbed by caustic soda solutions of greater than 2y0 sodium hydroxide concentration, and in which the caustic soda is continuously regenerated by continuous treatment with lime slurry, which precipitates calcium fluoride and recovers the caustic soda. The chemical reactions involved are as follows:
+ 2NaOH = 1/20, + 2NaF + HzO HF + NaOH = NaF + H20 2NaF + CaO + HzO = CaF2 + 2NaOH Fa
1 Present address, Scientific Design Company, Ino., 2 Park Ave., iiew Pork 16, N. Y. * Present address, Standard Oil Development Company, New York, N. Y .
DESCRIPTION OF PLANT
The major portion of the equipment employed i n this installation consists of ordinary steel and only those portionq of the tower and related apparatus which are likely to come in diyect contact with fluorine must be made of corrosion refiisting equipment. Carbon brick lining has been found to be satisfactoiy for this purpose. Other materials of construction suitable for rcsistancg against fluorine have been described (I).
INDUSTRIAL AND ENGINEERING CHEMISTRY
1390
u
Process FIOWSheet
Figitre 1.
The fluorine-containing gases ai'e introduced to a packed absorpt,ion tower, 1, through nozzle 2, Figure 1. The tower is fed with a countercurrent strram of 5 to 10% sodium hydroxide solution, which is int,roduced at the top of the tower through nozzle 3. Inert gas is vented through stack 3a. The effluent'liquid from the tower, containing sodium fluoride in solution, i s continuously withdrawn from the ton-er through line 4, and passed into a regeneration tank, 5 , to Khich is supplied, through line 6, a small stream of lime slurr5 which enters from slaker 7. I n the regeneration tank, 5, t,he sodium fluoride formed is converted to calcium fluoride by reaction with lime, under conditions of good agitation. The mixture flows through line 8 into a settling tank, 9, wherein the calcium fluoride and excess lime are settled out. The clear, regenerated liquor overflows weir 10 and is discharged through line 11 back to the absorption tower, 1. In order to maintain temperature control on the tower, the discharge from settling tank 9 first passes through a heat exchange system, 12. This system is automatically regulated to maintain a constant temperature of 100' to 150 a F. on the tower feed. The lime slurry is prepared by the addition of lime (quick or hydrated) from bin 13 to tank 7, using belt feeder 14. The slaking
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Figure 2.
Fluorine Receiled by Plant
~
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Vol. 40, No. 8 or slurrying medium i,portion of fresh tower f t x d recyclcd to tank 7 through line 15. This solution may be cooled b y p a s s a g e through exchanger 16. Incoming 50% sodium hydroxide solution is puniprd from tank car 17 through lint: 18 to storage tank 19, which is part,ially filled with xawr to make a 257, solution. Make-up alkali can be rvit 11d r a m from 19 as n e e d d and pumped through lints 20 to the settling tank, 9. When sufficient solids havt: accumulated in the scttlirig tank, the clear liquor is c1t'canted off through a swing pipe and pumped t'hrough line 21 to decantation tank 22. After the sett'ling taIlk has been cleaned, the clew liquor i s returned thereto from the decantation tank, 22. Waste solids in t,ho settling tank may be lonioved by adding sufficient uati>r to make a slurry, and puin1)ing t,hrough 23 lo disposal.
OPEK.4TIOS ?'I.:s'r
A I-moiith test ivas run on this unit for the purpose 01 furnishing engineering data for plant, operation. The results of this test demonstrate the basic operability of thP chemical regeneralive process. Fluorine was fed to the syst,eni at a rate of approxiniately 60 pounds per day with some fluctuations during the period of the test (Figure 2 ) . The rate of lime addition is shown irr Figure 3. OPERATIOV OF REACTIOR TANK
The soluble fluoride concentration in the tower feed is shown in Figure 4. During the period of October 13 to 22, the soluble fluoride concentration (expressed as fluorine in parts per million by weight) increased steadily from about 1000 to 3500 p.p.m. This was believed to be due to the lack of sufficient lime fed to the reaction tank. Accordingly, the lime rate was increased on October 23, and the fluoride concentration was then brought back to a level of about 1000 p.p.m. I t rose, thereafter, to about 1500 p.p.m. for a short nrhile; subsequently, it dropped back to about 1000 p.p.in. and remained at that figure. It is apparent that, over the month of operation, mhatever fluoride ]vas formed in the tower vias precipitated out in the reaction tank, as calcium fluoride. The value of 1000 p.p.m., which could not be reduced appreciably by greattr increase in the lime rate, evidently represents the limit of thc equilibrium of the reaction of lime \J ith soluble sodium fluoride in the presence of caustic. If the lime treatment had not bcen used during the run, the total fluoride concentration in the caustic would have incieawd by 10,000 p.p.m. of fluoride, or to about 2.07, by weight of sodium fluoride. This probably would have resulted in the precipitation of sodium fluoride in the tower (solubility of sodium fluoride in caustic is about 1.5%) and possihle plugging. Alonk with regeneration of the caustic, it was this eventuality which the ieaction ivith lime was designed to prevent. Another confirmation of the effectiveness of the regcncrative reaction is found in the data on the caustic strength from November 1 to 11; during this time the caustic concentration remained s t 7.4% (Figure 5 ) . Over this interval the toxw absorbed 720 puuncls of fluoriile (Figure 2 ) n-hich would have caused a
INDUSTRIAL AND ENGINEERING CHEMISTRY
August 1948
1391
AVERAGE
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Figure 3.
Lime Consumption
reduction of 0.8% sodium hydroxide in the caustic concentration if no lime treatment had been in use. During the earlier part of the month's run (not shown in Figure 5 ) the caustic concentration gradually dropped from about 8 to 7.4% as water was added to the system for washing out the lime slaking and other equipment. During the month's operation, the total fluorine fed was 1882 pounds and the lime fed was 8960 pounds. The theoretical lime requirement to precipitate all of the 1882 pounds of fluorine as calcium fluoride is 2770 pounds. It is evident, therefore, that the lime consumed was over three times the theoretical: the excess lime settled out along with the calcium fluoride. During the period October 13 to 22, the pounds of fluorine absorbed were 697, and the pounds of lime; 1780. As the theoretical lime requirement for this weight of fluorine is 1030 pounds, the excess was only '70%. However, the fluoride content of the solution increased almost continuously during this period. A higher ratio of actual to theoretical lime therefore appears necessary for completeness of reaction, somewhere between two and three times the theoretical. The thermodynamic data available in the literature are not sufficient to permit calculation of the equilibrium constant of the reaction between lime and sodium fluoride, and the observed data therefore cannot be checked. Equilibrium calculations (and analyses) are complicated by the fact that the reaction occurs in very dilute solution (except for the caustic) and involves only small changes over short time intervals. Calculations show that, a t a flow rate of 60 pounds per day of fluorine to the tower and a caustic liquor rate of 100 gallons per minute, the change in fluoride content of the solution through the absorption tower would not exceed 50 p.p.m. This value is well within the experimental error of the determination, so that the chart presented in Figure 4 is representative of the fluoride coni only tent a t all points in the system e t any given time. It R over a period of some days that the trend becomes observable. Therefore, it is not necessary to obtain more than a sample at the tower feed for routine plant control. During the period preceding the run, it was observed that the soluble fluoride content dropped about 100 to 900 p.p.m. when the temperature was raised from about 70' to 90 O F. This probably can be attributed to the increased solubility of lime and improved reaction rates. A similar effect would be expected in the case of a reduction in caustic strength, although this was not tried. It is believed that the optimum caustic strength for the whole plant is 5 to 8%. Further reduction of this value would lower the efficiency in absorbing fluorine and the efficiency of settling out the calcium fluoride (as observed experimentally). The data demonstrate that it is possible to keep the soluble fluoride content of 5 to 10% sodium hydroxide solution a t a satisfactorily low level (such as 1000 p.p.m.) when feeding lime at a uniform daily rate of about two to three times the theoretical amount required t o react with the fluorine consumed, without the necessity for close adjustment of lime rate t o fluorine rate because a deficiency or excess of lime feed for one day can be remedied the next.
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Figure 4. (A) Fluoride Ion Concentration-Settling Tank Overflow and Tower Effluent; (B) Turbidity of Settling Tank Overflow OPERATION OF SETTLING TANK
The data presented in Table I were obtained during experiments designed to estimate the efficiency of the settling tank. Almost independent of the entering solids content, the suspended solids in the effluent from the settling tank ranged from 93 t o 154 mg. per liter for samples taken a t various times during the period November 1 to 7. At the same time the range of entering solids in suspension was 202 to 900 mg. per liter. The overflow from the settling tank was relatively clear and the suspended particles were very fine.
TABLE I. EFFICIENCY OF SETTLING TANK Date Sample Point Nov. 1 Settling tank 1 Tower effluent 3 Reaction tank
Suspended Solids, Mg./Liter 154 154 211
% in CaFz CaFz, Mg./ Solids
81.5 83.0
70.4
Liter 125 128 148
3 4
Settling tank Reaction tank
140 290
..
64.0
186
4 6
Settling tank Reaction tank
140 202
86.1 65.3
121 132
6
7
Settling tank Reaction tank
93 900
34.0
89.3
83 306
7
Settling tank
130
87.3
114
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Remarks Control sample Control sample Flow of caustic so!ution 100 gal./ nun. Sample lost Flow of caustio so!ution 100 gal./ min. Flow of caustic solution 50 gal./
nun.
Flow of caustic sqlution 50 gal./
nun.
Increased lime feed
I n Figure 4 are presented data obtained with a turbidimeter. Although this was calibrated for another suspension and, therefore, has no absolute validity, it is clearly indicated that there was relatively little change in turbidity during the test, despite fluctuating lime and fluorine feed rates. There was some qualitative indication that a t the lower liquor circulating rates (50 gallons per minute), the settling efficiency was improved somewhat because of the increased holding time in the settling tank, but the data are not accurate enough t o establish a definite trend. The data also show that the amount of calcium fluoride in the solution was substantially reduced by settling. Thus, the outgoing calcium fluoride (in suspension) ranged from 83 to 121
INDUSTRIAL AND ENGINEERING CHEMISTRY
1392
ing. per liter, whereas the incoming calcium fluoride ranged from 132 to 306 mg. per liter. The amount of calcium fluoride which should settle out can be calculated readily from the amount of fluorine being absorbed by the tower. For the three days November 4, 6, and 7, the amount of calcium fluoride settled out corresponded to 3.5, 1.3, and 5.1 pounds per hour, respectively. Since the rate of fluorine absorbed during that period was about 60 pounds per day, the hourly rate was about 2.5 pounds, which is equivalent to 5 pounds per hour of calcium fluoride. It is apparent that the amount of calcium fluoride settled out is, in two cases, substantially equivalent to that formed in the reaction tank and, in the other cam, is of the right order of magnitude.
I O O ~
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-A-
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this indicated uniform flow from inlet to outlet across the tanks There was considerably more deposit a t the inlet point. corrcsponding t o the fact that more excess lime than calcium fluoride was t o be settled out; the lime, being of larger particle size, srttled first. The solutions left at the bottom of the tank at the end of the iun XT c w slurried up 1% ith water and pumped to a holding pond. Some measurements taken on October 22, at sample points near the bottom of the settling tank (Table 11),indicated that, except for the verylowest sample point-that is, a few inches from the bottom of the tank-the caustic concentration and soluble fluoridc content were identical with values obtained a t the tower outlet and tower inlet. This indicated that there was sufficient mixing in the system t o avoid stratification in the tank and that only at the lowest point, which probably represents solution occluded by settling solids, is there any deviation. This occluded solution vias higher in caustic and lower in soluble fluoride and, therefore, probably represented fresh caustic from the beginning of the run.
SO
OPERATIOU OF SLhKING T4NK OAY
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Figure 5. (4)Caustic Flow to Tower; (B) Caustic Temperature; (C) Caustic S t r e n g t h
Because of the extieme difficulty of obtaining true represcntati\ c samples and because of short time variation in conditions, it ii not believed that these results can be interpreted qiantitativiilv. They do indicate, however, that the amount of calcium fluoiide that settled out is roughly equivalent to that entering the system. This was confirmed by the fact that the calcium fluoride content of the caustic feed to the settling tank did not change much in the week during which the data were obtained (Table I) when the amount of fluorine absorbed was approximately 420 pounds, equivalent to about 860 pounds of calcium fluoride. If this calcium fluoride had not settled out, the observed concentration would have increased by about 5000 mg. per liter. It is possible that the minimum calcium fluoride retained in suspension (about 100 mg. per liter) is the amount of colloidal suspension stable under the prevailing conditions, and that calcium fluoride over this mininium is coagulated sufficiently to permit settling in the holding time involved. Previous laboratoiy experiments have sh0a.n that the caustic helps coagulate calcium fluoride and it appears likely that the suspended calcium fluoride circulating in the system would be much larger if water weye used. On the basis of this consideration, the caustic concentration should not be reduced too much. I n the absence of more data, i t is suggested that 5y0be the minimum caustic concentration employed. At the end of the run, inspection of the settling tank confiimed the findings of the efficiency determinations-namely, that most of the excess lime settled out near the entrance point, whereas the solids found near the weir overflow from the settling tank consisted of calcium fluoride. Solids were distributed fairly uniformly over the bottom of the tank in the transverse direction;
Early tests in the plant run nith a lime feed rate of well ovrr 1500 pounds per day showed that the slaking equipment could not handle such high feed rates, as evidenced by the fact that the lime settled out at the bottom of the slaker and various parts of the piping system; the cloudiness of the settling tank overflow also increased sharply. However, after experience showed that the soluble fluoride content could be maintained at an approximatelv uniform flow by feeding a small but constant lime stream, the slaking problem was considerably simplified. I t was found unnccessary to use a mechanical agitator for maintaining thrs lime in suspension, as air agitation was sufficient. 9 recycle rate of about 10 gallons per minute of clear sodium hydroxide wlution m-as employed; this pave a lime slurry of 0.2 to 0.4% b y n-eight of calcium oxide. This slurry caused very little trouble in the lines and necessitated only occasional wash downs at the measuring orifice on the line, the point a t which most of the plugging occurred.
TABLE 11.
COSCESTRATIOX
Sample Location Tower inlet. Tower outlet Rottoin of settling tank Lowest point
Next loxest point S e x t lowest point Last point
STUDY IX
SETr1,INc; T a S K
26.0
Fluorine Lfg./Lit& 3240 3250
27.3 26.0 26.0 26.0
900 3310 3320 3380
Temp.,
O
26.0
C.
?/; XaO tI 7.4 7.4
10.4 7.4
7.4 7.4
Toward the end of the run commercial hydrated lime was substituted for pebble quicklime because of the unsatisfactory quality of the latter. This seemed to improve the slaking operation somewhat and did not affect visibly the turbidity of the solution leaving the settling tank. Accordingly the use of pebble quieklime was abandoned. (Experiments run with the pebblr quicklime revealed the presence of a large part of silica and other inert material: it was observed that at least 30% of the lime added settled very rapidly and, therefore, probably did not conti ibute materially to the reaction.) The lime feeders appeared t o operate satisfactorily. As a result of the lower caustic temperatures employed during the run, there was substantially no steaming at the slaker and, consequently, no caking of lime on the belts, as was encountered previously in the plant with higher caustic temperatures. As a result of the low lime feed rates, the heat of slaking became negligible and it was not necessary to use the recycle caustic cooler.
August 1948
1393
INDUSTRIAL AND ENGINEERING CHEMISTRY OPERATION OF TOWER
ACKNOWLEDGMENT
Tests made employing a sensitized paper detector indicated that the fluorine was almost completely absorbed, and the concentration of fluorine (or hydrogen fluoride) in the gases from the 4-foot diameter tower, at fluorine feed rates u p to 500 pounds per hour, did not exceed 3 p.p.m,, which is believed to be nontoxic ( 1 ) . SUBSEQUENT EXPERIENCE
After the run described in this paper, the installation operated smoothly for an extensive period of time; this supported the observations made during the month of testing.
The assistance of H. A. Rehnberg of the Kellex Corporation, under whose supervision the plant was constructed and operated, and W. C. Moore and E. W. Thomas of Ford, Bacon, and Davis, who conducted the tests, is acknowledged with appreciation. This Paper is based on work done for the Manhattan Project under contract, W-7405-Eng. 23, a t the Kelley Corporation. LITERATURE CITED
(1) Landau, R., and Rosen, R., IND.ENG.CHEM.., 39,281-6 (1947). (2) Turnbull, S. G., Benning, A . F., Feldmann, G . W., Linch, A . L., McHarness, R. C., and Richards, M. K., Ibid., 39, 286 (1947).. Presented as a p&Tt of the Symposiul,l on RECEIVED November 1, 1947. Fluorine Chemistry, Division of Industrial and Engineering Chemistry. a t the 112th Meeting of the ANERICANCHEarIcAL SOCIETY, New York, N, Y .
LACTIC ACID POLYMERS As Constituents of Synthetic Resins and Coatings PAUL D. WATSON Agricultural Research Administration, U . S . Department of Agriculture, Wushington, D . C.
The
paper describes modified lactic acid condensation polymers dqveloped in the Division of Dairy Research Laboratories which may be of interest to the coatings industry. The most useful of these products appears to be a modified polylactylic acid-fatty oil polymer, from which tough, water-resistant coatings may be formulated. Another class of resins is the metal polylactyl lactates derived almost entirely from lactic acid; these may be used for protective and decorative coatings.
T
HE lactic acid of commerce is produced by fermentation of
the carbohydrates present in corn sugar, molasses, and whey. It has been estimated that the whey produced annually as a by-product in the manufacture of cheese and casein contains about 500,000,000 pounds of lactose, which is a potential source of about 400,000,000 pounds of lactic acid. Although approximately 6,000,000 pounds of lactic acid (100% basis) produced from all sources are utilized annually by various industries, the relatively high price of the purified acid has apparently retarded greater use. About 400,000 pounds are used in the plastics industry-chiefly as a catalyst and plasticizer in cast phenolic resins. Adoption of the methyl lactate purification process (10) or of the selective extraction method for the recovery of lactic acid esters (3) eventually may lower prices for the high grade acid. With the above considerations in view, research workers in the Division of Dairy Research Laboratories developed a number of resins which are based largely on lactic acid. The can manufacturing industry became interested in their possibilities as a coating for tin cans and sesearch was continued. Then the critical shortage of tin during the war caused serious concern in the milk industry, and further work was carried out with the object of obtaining a coating for milk cans which would substitute for tin. Shortages of other basic chemicals used in the plastics industry-such as phthalic anhydride, glycerol, and oils-made further studies of lactic acid based resins appear desirable. More detailed information will be found in the patents of reference. The brief survey of lactic acid resins made by Light (9) shows that considerable interest has been directed to this field over a period of years. Several patents (7, 8, 1.8) mention lactic acid as a constituent of various plastic materials. Stearn, Makower,
and Groggins (11) have investigated lactic acid as a coniponent of alkyd resins. I n considering the economic phases, they expressed the opinion that i t may become an important. industrial chemical if the cost can be made comparable with other resin ingredients. POLYMERIZATION OF LACTIC ACID
Bezzi ( I ) , Hovey and Hodgins ( 6 ) , and Flory ( 5 ) have discussed the theoretical aspects of the linear condensation polyiners formed from lactic acid, and the subject need be outlined oiily. When a solution of lactic acid is dehydrated by heating, interesterification occurs by loss of water between the carboxyl and alpha alcohol groups, and monolactyllactic acid, CH3.CHIOH)COOCH(CH8)COOH, dilactyllactic acid, tri-, tetra-, and finally polylactylic acids consisting of long chain molecules of the folloiving type are formed successively: ’
H- [OCH(CHa)CO]z--OH
The reaction may proceed intramolecularly also wit,h the Eormation of the cyclic-dimeric compound, lactide: CHJ-CH-0-CO
1
1
CO-O-CHCH3 Some of the latter compound is usually formed, dependiiig 011 the reaction conditions, and a portion generally escapes because of its ease of sublimation. The water freed during the interesterification reactions evidently hydrolyzes part of the lactide to lactyllactic acid, which then reacts with other lactide molecules by ester interchange. The functional groups apparently react with each other at random, and the polymerization proceeds by the addition of the monomer or cyclic dimer to the linear chains. The bifunctional nature of lactic acid, therefore, makes it possible to form resinous polymers by self-esterification. However, these simple resins have very little utility because they are brittle, have a high acid value, and lack water resistanqe- The writer has found that useful resins may be formed by causing polylactylic (polylactyllactic) acid to react with other a g w t s containing functional groups-such as alcohols, aldehydes, carbohydrates, fatty oils, and certain metal salts. Apparently the functional groups of these compounds react with the hydroxyl
