INDUSTRIAL AND ENGINEERING CHEMISTRY
784
growth on optical glass in binoculars. HoLvever, mold growth occurred on all surfaces which were not adequately protected, and on nonglass surfaces, such as metallic parts (retaining and reticle rings), cork pads, grease, and sealing compounds. The growth of fungi from nonglass surfaces to the margins of optical g!ms elements protected with radioactive materials offers a serious draqback to their use. Because alpha radiation is stopped by 39 microns of fungus tissue, it is conceivable that sufficient growth could occur a t the edges of the glass to stop the radiation. Radioactive emanations would not prevent the entrance of animal vectors, such as mites. The mites would die on the glass surfaces and could serve as centers of mold growth. The dead organism would shield any germinating fungus spores from the alpha radiation. Owing to the difficulty in protecting binoculars with radioactive materials and the potential health hazards in their application to the instruments, other methods for the prevention of the deterioration of these instruments should be considered. However, for the protection of simple optical instruments not containing prisms or for special instruments which cannot be pxotected by other means, the use of radioactive materials may be desirable. The internal surfaces of binoculars may also be sterilized periodically by ionizing radiation from high-voltage machines. I n order to use this external source of radiation, the optical gldsses now used will have to be replaced with glasses that do not darken when exposed to the high-energy radiation. ACKNOWLEDGMENT
Appreciation is expressed to C. C. Fawcett and E. R. Rechd of the Pitman-Dunn Laboratories and to the Ordnance Corps, Department of the Army, for permission to publish this paper. Special thanks are due IT. L. Steinbach for light-transmittance measurements.
Vol. 46, No. 4
LITERATURE CITED Berk,
S.,J l y c o l o g i a , 44,
587-95 (1952).
Ibid., 45, 458-506 (1953). B e r m a n , I. L., and E a r n e s t , E. P., Ind. M e d . and Surg., 19, 22930 (1950). B r y a n , F. A , , a n d Silverman, L. R., “Interna: Radiation E a z t r y from the Use of Polonium in Static EliminaU. S. Atomic Energy Commission, AECU-343 (1949). E v a n s , R . D., “ E x t r a c t from Report on Polonium Static Eliniinator Devices to Canadian Radium 6: Uranium Corp.,” 1949. E v a n s , R . D., J . Ind. Hyg. Toricol,, 28, 243-56 (1946). Friedlander, G., a n d Kennedy, ,J. W., “Introduction to Radiochemistry,” Yew Yolk, J o h n Wilcy 6: Sons, 1949. Hutchinson, W. G., J . Bacterid., 54, 45-6 (1947). Jones, F. L., C h e m Eng. News, 19, 390 (1941). R e r n o h a n , R. H., a n d l I c C a m m o n , G . hl., “ F a d i n g Characteristics of Gamma-Induced Coloration in High Density Glass,” U. S . Atomic Energy Cornmission. ORNL 975 (1951). l I o n k , G. S., ”Coloration of Optical .\laterials by High Energy R a d i a t i o n s , ” U. S. Atomic Energy Commission, ANI, 4536
(1950). M o n k , G. S.,Nucleonics, 10, S o . 11, 52-5 (1952). Kordblom, G. F., “Condensate Formation on the Interior Optical Surfaces of 6 X 30 Binoculars,” Frankfcrd Arsenal Ord, Laboratory, Memorandwn Rept. MR-379 (1947). Slater, J. C., J . A p p l . P h y s . , 22, 237-56 (1951). S m y t h , €1. D., “Atomic Energy for Military Purposes,” Princet o n , S . J. Princeton University Press, 1946. Stenstrom, W,, and Vigness, I., J . Chem. Phus., 5 , 298-301 (1937). Stockdale, G. F., a n d Tooley, F. V., J . Am. Cemm. Sac., 33, 11-16 (1950). Teitell, L., a n d Berk, S., ISD.EXG.CHEX, 44, 1088-95 (1952). U. 9. Army Specification 51-70-2C, “Optical Components for Fire Control I n s t r u m e n t s : General Specification Covering the AIanufacture, Assembly a n d Inspection of,” 1951. Vicklund, R . E., I s n . ENQ.Cmar., 38, 774-9 (1946). TVillianiu. C‘. R.. J . I n d . Hag. Tozicol.. 30, 594-9 (1945).
RXCEIV~X for review October 1 5 , 1Qj3,
. ~ C C E P T C DDecember
1 , 1933.
Thermal Isomerization of Gum Rosin J. S. STINSOX AND RAY V. LIWRENCE Naval S t o r e s Research Division, Southern Regional Research Laboratory, Olustee, Fla.
T
HE effect of temperature on the physical and chemical
properties of gum rosin is an important problem. Since the industrial utilization of rosin generally requires that it be processed at temperatures between 225” and 290” C., a study was made of the effects of temperatures in this range for time intervals up to 8 hours. As rosin is sometimes stored by resin manufacturers for a few days at temperatures around 155’ C., one run was included a t this temperature. It has been shown by others (2, 3, 8, 13, 14) that approximately one half of the acidic portion of rosin may be converted to abietic acid by thermal or acid isomerization. It has also been shown (3-7, 9, 12, IS) that on continued heating abietic acid undergoes several reactions, including dphydrogenation, disproportiondtion, isomerization, polymerization, decarboxylation, and anhydride formation. The acids present in rosin that cannot bc isomerized to abietic acid, such as dextropimaric, isodextropirnaric and dihydro- and dehydroabietic acids are fairly stable at temperatures of 250” C. Some decarboxylation of these acids may ocrur a t higher temperature, but this group of acids would be expected to account for a very minor part of the changes taking place in the rosin. Many of these changes are interrelated. For example, the increase in the Boftening point, the change in optical rotation from positive to negative, and the increased tendency for the
rosin to crystallize that occur with moderate heating are causrd principally by the increase in abietic acid content of the rosin. As this heating is continued or as the temperature is increased all of these changes are reversed. The optical rotation becomes more positive. there is less tendency to crystallize, and there is n gradual decrrdse in softening point. EXPERIMENTAL PROCEDURE
Guin rosin samples of 300 grams each were heated in threenecked, 500-ml. round-bottomed flasks equipped with stirrer. side-arm trap, thermometer holder, and nitrogen inlet tube The temperature was controlled within i.5’ C. and the sample4 were heated a t such a rate that approximately 20 minutes wa.i required to obtain the desired temperature. A slow current oi nitrogen (20 to 25 ml. per minute) was passed over the rosin to provide an inert atmosphere. Samples of each run were removed a t suitable intervals and grade, acid number, softening point, and optical rotation were determined. Saponification numbers were determined on the original and final products. Grade samples were allowcd t o cool in containers in the presence of carbon dioxide. Grade, acid number, saponification number, and softening point (ring and ball) were determined by ASTlI methods. Optical rotatior
INDUSTRIAL AND ENGINEERING CHEMISTRY
April 1954
T~
EFFECT OF HEAT(155' C.) ox PROPERTIES O F GUM ROW
I . EI.
Crystallization SoftenTimeb from ing Pt., Acid Acetone Soln., Grade C NO [ a ] y Hours 0 WW 74 0 168.2 +13.1° No crystals 3 WG 74 0 20 168.4 f21.30 7 TVG 75.0 2 168.1 +12.4' 31 N 9.8; 78.0 166.6 I/% N 164.1 58 -20 7 81.5 ]/e R ,5 163.1 AI -26.0' 83.0 I/( 14.5 -21.70 162.1 AI 86.0 l/e -24.80 103 K 162.3 87.5 I/( 2% solution in ethvl alcohol. b Time reauired for first crystal to appear i n acetone solution, Palkin and Smith method (ff). Tiwe. Hollis
-
+ S O L
250
i
O P b J -
-20
i
l
O
I
l
225
V
2
3
4
5
6
I I
I
t
7
8
HOURS
Figure
P. Effect of Heat on Specific Rotation of Gum Rosin Temperature, 225O to 290° C.
determinations were made using a 2% solution of the rosin in ethyl alcohol. The tendency of the rosin to crystallize was checked by the method of Palkin and Smith ( 1 1 ) . This method consisted of placing 10 grams of broken lumps of rosin in a test tube (150 mm. long, 18 mm. in outer diameter) and adding 10 ml. of aretone. The test tube was stoppered and allowed to stand undisturbed. The time required for the first crystals to form was recorded. Rosins which show a tendency to crystallize will do so within 12 hours. Runs were made with commercial gum rosin a t 156", 225", 275", and 290' C. Samples of rosin prepared in the laboratory from pure slash (Pinus carribea) and pure longleaf (Pinus palustris) oleoresin were also included. These species of pines are the only ones used for the production of gum naval stores in this country. The slash pine provides the greater portion of the rosin. At the present time gum rosin will vary from 60 to about 90% slash rosin. An additional series of runs was ma'de duplicating the first series, with the exception that no samples were removed, to determine the amount of material volatilized. The results of these runs are listed in Table 111. The rate at which the nitrogen was passed over the samples (25 ml. per minute) was carefully controlled. The distillate collected in the Dean-Stark trap consisted of approximately equal quantities of aqueous and nonaqueOUB material. Titration of the aqueous layer showed i t to be 35% acid, calculated as acetic acid. Duclaux values on the distillate indicated that it was principally acetic acid with formic acid as a minor constituent. RESULTS
CRYSTALLIZATION. The crystallization of rosin increases the difficulty of handling the material and is also highly undesirable
785
for some uses such as the preparation of paper size, One of the effects of moderate heating (155' to 250' C.) on rosin was to increase its tendency to crystallize. Gum rosin ordinarily is noncrystalline but as the heat isomerized some of the other acids present into abietic acid, the rate of crystallization increased. While the tendency of rosin to crystallize is greatly influenced by the concentration of abietic acid present, the abietic acid content of the crystals formed is only slightly greater than that of the rosin from which i t crystallized. Under more drastic conditions the abietic acid present was disproportionated and polymerized to form a noncrystalline product (1, 3,10, 15). The tendency of these samples to crystallize was determined by the method of Palkin and Smith (11). Tables I and I1 show the length of time required for crystals to appear in the acetone solution. After heating a t 155" C. for 7 hours the rosin required 2 hours to crystallize from the acetone solution and after 31 hours a t this temperature the acetone solution formed crystal8 in 10 minutes. It required only about 15 minutes a t 275" C. for the rosin to reach its maximum tendency to crystallize and after 2 hours a t this temperature the rosin no longer showed any appreciable tendency to crystallize. At 290" C. the rosin was converted to a noncrystallizing product in considerably less thaa an hour. OPTICALROTATION.The effect of temperature on the optical rotation of rosin is shown in Figure 1. The specific rotation of these samples was measured in a 2% solution of rosin in 95% ethyl alcohol. The first change in rotation on moderate heating, from positive to negative, involves the isomerization of neoahietic acid, [a], = +159", to abietic acid, [a], = -106'. The change from negative to positive that occurs on more drastic heating involves the dehydrogenation of the abietic aci'l to dphydroabietic acid, [a],= +64". Other changes that occur on prolonged heating also influence the rotation, but those mentioned would be expected to have the greatest effect. The opticnl rotation of rosin is useful as an indication of its tendency to
TABLE 11. EFFECTOF HEATON COLORAND CRYSTALLIZATION OF WW GUMROSIN Temp.,
c.
Time, Hours
Color Grade
ww
225
N N N
Crystallization Timea from Acetone Soin., Hours No crystal3
'/ 6 '/e 1/i
N
'/e
...
N N N
'/c
...
N 25 0
0 1 7
3 4
5 6 7 8
273
W
w
#/k
?U'O crystal,
pi
I/& I/ 2
N N N WG WG WG WG
2 N o crystals
WW
N o crystals
% Ww ww X X X
X
1/4
...
KO
Orystals
4b N o crystals
... ... ...
XOcrystale NO
Or'&tals
Time required for first crystal t o appear in acetone solution, Palkln and Smith method (11). b Scetone solution crystallized in 15 minutes and 1.25 hours from samples that had been heated a t 275O C. for 15 and 45 minutes, respectively.
786
INDUSTRIAL AND ENGINEERING CHEMISTRY
120
I 1
I .
I
I
2
3
4
5
6
7
8
HOURS
Figure 2.
Vol. 46, No. 4
HOURS
Effect of Heat on Acid Sumber of G u m Rosin
Figure 3. Effect of Heat on Acid Number of Longleaf, Slash, and Commercial Gum Rosins
Temperature, 225' to 290' C .
Temperature. 2i5' C.
I
90,
E5
I
I
I
I
I
I
I
1
2
3
4
5
6
7
' 8
HOURS
0
7
1
2
1 3
I 4
I
I
5
6
7
HOURS
Figure 4. Effect of Heat on Softening Point of Guni Rosin
Figure 5 . Effect of Heat on Softening Point of Longleaf, Slash, and Commercial Gum Rosins
Temperature, 225' to 290" C.
Temperature, 275O C.
crystallize. If the rosin has not been heated strongly enough to have a negative rotation, there is seldom any trouble from
*4t 275c C. and above a niasimuin ir-as obtained followed by a. gradual decrease. arid only at 200" C. did the softening point fall below the softening point of the original rosin. At 158" C. the softening point rose from 74" to 87.6' C. in 195 hours and was continuing to increase. A comparison of the effects of temperature (275" C.) on t h e softening point of pure slash and pure longleaf rosin with a sample of commercial gum rosin is given in Figure 5. COLOR. The effect of temperature on the color of rosin is shown in Tables I and 11. At 225" C. and below there was a gradual darkening of the rosin while a t 280' C. and above there \%-assome darkening a t first, follon-ed by an improvement in color. The first darkening xr-as probably caused by surface oxidation of the rosin before it \TRS melted and the cont,inued darkening that occurred a t 1%' C. may have been caused h y the small amount of o en present in the nitrogen. .it temperatures above 260" C. the'color bodies produced by oxidation vcre apparently decomposed.
crystallization and if the rosin has been heated enough to give it a positive rotation! it has usually undergone enough niodification to lose its tendency to crystallize. A rosin that has been dieproportionated by heating with a catalyst (4,6 ) has a high positive rotation and a very strong tendency to crystallize. ACIDNUMBER.The effect of temperature on the acid nuinber of rosin is shown in Figure 2 and in Table I. The deer the acid number of abietic acid was shown by LaLande ( 6 ) to be caused principally by anhydride format,ion below 275' c'. Only a t higher teiiiperat,ures did decarboxylation play a bignificant part in the decreased acid number. The decreaae in acid number of the rosin was considerably greater than that reported for pure abietic acid. The rosin used in the rune reported in Figure 2 had a saponification number of 173. This decreased only nine units in heating for 8 hours a t 228' C. and 16 units after 8 hours a t 260" C. At 275" C. the saponification number deereased from 173 to 145 in 8 hours and the acid number dropped from 168 t'o 127 during the same period. The difference between the acid number arid the saponification number of rosin is probably due t o the presence of the anhydrides of the resin acids (9). This indicates that about 10% of the acids present in the original rosin was converted to the anhydride by heating a t 275' C. for 8 hours. Figure 3 gives a comparison (at 275" C.) of the effcet of tempera.ture on the acid number of pure longleaf and pur? slaah rosin with a commercial sample of gum rosin. SOFTESIXO PoisT. The effects of temperature on the softening point of rosin is listed in Figure 4 and Table I. I n all rases the softening point of the rosin increased with inoderat,e heating.
TABLE 111. VOLATILEX ~ T TFROM E RROSIN (Runs a t 2 2 5 O , 2 5 0 ° , and 278O C . were l o r 8 hours; 290' C.1i:n wa8 f o r 7 hours) Material in Dean-Stark Trap ~ ~cnact , Temp., Aqueous, To of Nonaqueous 70 counted for", O c. orig. rosm of orig. rosin 470 0.1 0.1 1.0 223 0.4 0 4 0.6 230 1 2,: 0.Yb 0.7 2,' 0.9b 1 0 290 li Total loss in weight not eccounted for, includes CO1, CO, EL, and C H I . b Aqueoua layer consisted of 35% acid. calculated as acetic acid. Duc l a w values indicated it t o be a mixture of acetic and formic acids.
.E
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
April 1954
LITERATURE CITED
(1) Butts, D. C., U.S. Patent 1,791,658 (Feb. 10, 1931). ( 2 ) DuPont, G., and Dubourg, J., BziZZ. inst. pin., 1928, 181. (3) Fanica, Rl., I b i d . , 1933, 151-65, 181-9. (4) Fieser, L. F., and Campbell, W. I'., J . Am. Chem. Soc., 60, 159
(1938). (5) Fleck, E. E., and Palkin, S.,I b i d . , 60, 921 (1938). (6) Ibid., 61, 247 (1939). (7) Greth, A., 2.angew. Chem., 47, 827 (1934). Chem. (8) Harris, G. and Sanderson#J. F.s J . (1948). c.p
709
334
(9) LaLande, W. A., IND.ENQ.CHEM.,26, 678 (1934). (10) Logan, W. B., U. S. Patent 1,643,276 (Sept. 20, 1927). (11) Palkin, S., and Smith, W. C., Oil & Soap, 15, 120 (1938). (12) Ruzioka, L., Bacon, R. G. R., Stemback, L., Waldman, H., Helv. Chim. Acta, 21, 591 (1938). (13) Rurioka, L., and Meyer, J., Ibid., 5 , 315 (1922). (141 Ruzicka, L., and Shins, H., Ibid., 6, 662 (1923). (15) Sanderman, W., Fette u. Seifen, 49, 578 (1942). RECEIVED for review September 18, 1953. ~ C E P T E DNovember 19, 1953. Presented before the Division of Paint, Plastics, and Printing Ink Chemistry a t the 123rd Meeting of the AMERICANCHEWICAL SOCIETY, Lo8 Angelee Calif.
Catalysis with Cation-Exchange Resins PREPARATION OF 1,3-DIOXOLANES AND 1,3,6-TRIOXOCANES MELVIK J. ASTLE, JOEL A. ZASLOWSKY1, AND PAUL G. LAFYATIS Case Institute of Technology, Cleveland 6, Ohio
THE
cyclic acetals and ketals made from vicinal glycols and aldehydes or ketones have the general structure R2-C-0
in which the R groups may be the same, or different, or may be hydrogen. These compounds are usually named as derivatives of 1,3-dioxolane. Although acetals can be formed noncatalytically by heating the reactants for some time, the reaction proceeds more easily under the influence of acid-type catalysts. For example, Neish and MacDonald (9) reported the use of hydrochloric and sulfuric acids as catalysts for the formation of acetals. Clark (6) used phosphoric acid as a catalyst and Meyer ( 7 ) lists stannic chloride, ferric chloride, boron trifluoride, and p-toluenesulfonic acid as effective catalysts for the reaction. Iieish (8) describes the formation of a cyclic ketal from ethyl acetoacetate and l-2,3-butanediol in the presence of hydrochloric acid and ptoluenesulfonic acid. Tink and Neish ( 1 7 ) describe the extraction of 2,3-butanediol, glycer~l, sugBrs,, and sugar alcohols as cyclic acetals and the subsequent recovery of the polyhydroxy compounds. The cyclic acetals of butyraldehyde were particularly effective and were prepared in the presence of dilute hydrochloric acid. Tink, Spencer, and Roxburgh (18) used a cation exchange resin (Duolite C3 obtained from the Chemical Process Co., San Francisco, Calif.) for the preparation of cyclic acetals of glycerol and aldehydes, particularly butyraldehyde. These acetals were used for the separation of glycerol from dilute aqueous solution. Roxburgh (12) also describes a process for removal of glycerol as cyclic acetals from dilute aqueous solutions. Senkus (IS) describes the recovery of 2,3-butanediol, as 4,5-dimethyldioxolane from fermentation beers. The formation of the cyclic acetal was catalyzed by sulfuric acid. Backer ( 1 ) passed 2,3-butanediol vapor over aluminum oxide a t 350" to 400' C, and obtained 2-methyl-2-ethyl-4,5-dimethyldioxolane.Methyl ethyl ketone was probably formed as an intermediate which reacted with the 2,3-butanediol t o form the cyclic acetal. Cation exchange resins of the sulfonic acid type, such as Amberlite 120, Dowex 50, or Zeo Karb H (16),are effective in promoting these reactions. Ion exchange resins have certain inherent ad1
Present address, hlathieson Chemical Corp., Niagara Falls, N. Y.
vantages over the conventional acids listed above. Removal or neutialiaatiori of the acid catalyst upon completion of the reaction piesents no problem, as the resin can be removed by simple filtration or decantation. The catalyst lends itself to use in a continuous process where the reactants are introduced into a column packed with the resin and the product mixture is continuously removed. Under ordinary conditions the resin does not require regeneration and the product is not contanmated with the catalyst. Furthermore, corrosion problems are minimized, as the hydrogen ion is present only on the surface of the resin and is not free t o attack metal equipment, as when conventional acids are used. Diethylene glycol and formaldehyde might be espected to form a linear polyacetal of the type [CH~-O-CH*-CH2-eCH,-CH*-O~
I
[n order to confirm this a mixture of diethylene glycol and formaldehyde was made to react in presence of Amberlite IR120 in the hydrogen ion state. Attempts to isolate the expected polyacetal were completely unsuccessful; instead, a fraction which boiled a t 150' to 153' C. at atmospheric pressure was isolated. This boiling point wa8 much too low for the unreacted glycol and the fraction did not give a positive aldehyde test with Tollens' or Fehling's reagents. Seymour (14) describes the preparation of a cyclic acetal from formaldehyde and diethylene glycol, by refluxing molar amounts for 18 hours in the presence of hydrochloric acid. Fractional distillation then produced his product, which boiled from 180" t o 240°C., a 60" boiling range. Diethylene glycol boils a t 246", indicating that Seymour obviously had an impure product probably diluted with a large amount of diethylene glycol. Ilurd ( 6 ) reported the preparation by an indirect method of the methyl derivative of the cyclic formal of diethylene glycol, which was indexed by Chemical Abstracts as a derivative of 1,3,6 trio xocane. 2
6
