Standardization of Kauri Butanol Test for Paint and Lacquer Thinners L. C. BEARD,V. L. SHIPP,AND W. E. SPELSHOUSE, Socony-Vacuum Corporation, New York, N. Y.
I
N DETERMINING the suitability of a solvent as a paint
and lacquer thinner, the kauri butanol test is one of the most important items in the specifications to be met. I n spite of its widespread use by the paint and lacquer as well as the petroleum industry, however, the results have not been consistent, and different laboratories have a t times been unable to check closer than 2 or 3 points on a solvent having a kauri butanol value of 35 to 45. The object of this investigation was to study the different variables of the kauri butanol test and to determine to what extent deviations in procedure would affect its results.
36 FIGURE
37
a8
1. EFFECT OF GUM CONTENT BUTANOL VALUE
39 ON
pared from the tree, (b) the same resin after exposure to the air during 1.5 or 4.5 years (Buschhars), (c) fossil kauri gum (range gum), and (d) kauri resin obtained from the peatmoors (Sumpfharz). He concluded that the per cent of pinene (the essential oil component) decreases regularly with increasing age of the resin, the optical rotation of the pinene decreasing in the same sense. The "range gum" showed 6 per cent of a high-boiling fraction of camphor-like odor, probably fenchyl alcohol, which probably was formed from the pinene under the influence of water and salts. I n case (d) pinene, dipentene, and fenchyl alcohol were found. Investigation of the resins left behind after the distillation of the crude resins with water showed that the amount of a-resin (low-melting resinic acids) decreases, and the amount of &resin (high-melting resinic acids) increases with the increasing age of the crude gum. Six samples of selected kauri gum were obtained from four different dealers in New York. Solutions of each gum were made by adding 200 grams of butanol to 60 grams of the cleaned and pulverized gum. The solutions were refluxed on a hot plate until solution appeared complete. They were then filtered through a Buchner funnel with a small amount of Sil-0-Gel to aid clarification, using suction. This produced a clearer solution than decanting after 96 hours and saved 4 days of waiting. Solutions of the same gum made by both methods gave the same kauri butanol values. The nonvolatile content of each solution was then determined accurately by weighing out 3 to 4 grams of the solution on the lid of a quart tin can. The lids were dried in an oven at 250' F. (121.1' C.) t o constant weight, which required about 2 hours.
KAURI
It was decided a t the start to follow, as closely as possible, the method adopted as official in 1931 by the Paint and Varnish Superintendents' Club of the Philadelphia District (7): One hundred grams of carefully selected pulverized kauri gum are dissolved in 500 grams of butyl alcohol distilling from 114.4' to 116.6' C. (238' t o 242' F.) using a water-cooled reflux condenser to facilitate solution. This mixture is then allowed to cool, and after 96 hours it is decanted into a clean, dry bottle and well stoppered.
No particular type of kauri gum is specified, and there is no assurance that two solutions made from different sources of kauri gum will have the same gum and moisture content (since gums vary in solubility and moisture). This method of preparing the solution, therefore, provided three points to be investigated: effect of the source of the kauri gum, effect of concentration of the solution, and effect of moisture in the solution. I n making the kauri butanol test, one method calls for the use of 25 cc. of kauri solution, and another for 20 grams, while in one case the materials while titrating are to be kept a t 68' F. (20" C.) and in the other a t 77" F. (25" (3,). These varying test methods, therefore, call for two further conditions to be studied: the effect of relative amounts of kauri butanol solution used and the effect of temperature.
FIGURE2. EFFECTOF RELATIVE AMOUNT OF SOLUTION USEDON KAURI BUTANOL VALUE The gum concentration of each solution was then adjusted t o 16.6 to 16.7 per cent by adding butanol, and kauri butanol values were obtained with each, using a petroleum lacquer diluent, and the official method of the Paint and Varnish Superintendents' Club of the Philadelphia District (7). The results appear in Table I. TABLEI. KAURIBUTANOL VALUESOF GUMSFROM DIFFERENT SOURCES
EFFECT OF SOURCEOF GUM Hosking (5) investigated the composition of the four types of kauri gum produced: (a) kauri resin freshly pre307
KAURIBuAPPEARANCE TANOL VALUE Light-colored chips 36.2 Large light-colored lumps, very clean 35.3 3. Bush kauri Light-colored chips 36.1 4. Fossil XXX Large dark-brown lumps 35.8 Large light-colored lumps, cov5. No. 1 pale (probably fossil) ered with dark crust 37.1 6. Fossil Mixture of dark and light chips 37.8 TYPEOF GUM 1. Bush kauri 2. Bush dial kauri
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ANALYTICAL EDITION
Vol. 5, No. 5
From the foregoing results it would appear that the choice of gums for the preparation of the kauri butanol solution determines to a considerable extent the kauri butanol values obtained and may produce a variation of as much as 2.5 points such, as was found between solutions of samples 2 and 6. Because of its uniform appearance, gum 2 was selected for use in all of the further work.
EFFECT OF CONCENTRATION OF GUM A large batch of kauri butanol solution was made up, using the bush dial kauri (gum 2) in the proportion of 100 grams of gum to 500 grams of butanol. This produced a solution with a nonvolatile content of 14.6 per cent, about 2 per cent of gum being insoluble. This was increased to 16.6 per cent by boiling off the calculated amount of solvent, and incidentally producing an anhydrous s o l u t i o n (butanol forms a 10 20 sa binary m i x t u r e containing 37 per FIGURE4. EFFECTOF MOISTUREIN KAURISOLUcent of water and boiling at 92.3" TION ON KAURIBUTANOL VALUE C.). About a pint of the 16.6 per cent solution was further concentrated to 21.3 per cent. Using these up again, and the new reading recorded. This was repeated at two solutions and the proper amount 76") 77") 80")83", and 85" (22.4")25", 26.7")28.2")and 29.4" C.), of butanol, eight 50-gram solutions The plot of these results appears in Figure 3. To check were prepared, ranging in gum content from 12.0 to 21.3 per cent, and these determinations, separate samples were run a t 72" F. 20-gram samples of each titrated in (22.2' C.) and 77" F. (25" C.) Both points fall on the line, a 250-cc. E r l e n m e y e r at 77" F. (25" C.) with the same petroleum within the limits of experimental error. A discrepancy of 1.3 per cent in the kauri butanol numbers 37 as solvent t o obtain the kauri butanol of a paint and lacquer solvent will result if the test is made a t FIGURE3. EFFECT OF 68" F. (20" C.) in one instance and a t 77" F. (25" C.) in * anTEMPERATURE ON KAURI BUTANOL VALUE From the results of these titra- other. tions the graph shown in Figure 1 EFFECT OF MOISTURE was obtained, which indicates that the kauri butanol value deSamples of kauri solution containing from 1 to 10 per cent, creases in a straight-line function as the gum concentration by weight, of added water were titrated to the regular end increases. Inasmuch as some description of the kauri test mentions point with a petroleum lacquer diluent. Figure 4 shows that an 18 per cent kauri gum content of the solution, an error the amount of diluent added decreases regularly in a straight line as the water increases up to about 7 per cent, where there from this source may be as high as 1.3 per cent. is a sharp break in the curve and a rapid decrease in the EFFECT OF RELATIVE AMOUNT OF KAURI BUTANOL SOLUTION number of cubic centimeters which can be absorbed without clouding. Since the solubility of water in butanol is 7.3 per USED cent at 77" F. (25' C.), this is not unexpected. Eight samples containing from 17.8 to 22.5 grams of 16.6 OF SOLVENT POWER IN TERMS OF TOLUENE per cent kauri butanol solution were titrated with the same EVALUATION VALUE petroleum lacquer diluent in the regular manner. Plotting It is clear from the above discussion of experiments that the results produces a straight line, as is shown in Figure 2, and proves that the kauri butanol value is directly propor- all sources of inconsistency in results of the kauri butanol tional to the amount of kauri solution titrated. Two labora- test can be easily eliminated by adopting a standard procetories using 25 cc. and 20 grams of kauri solution, respectively, dure, with the exception of the uniformitv of the basic material, the kauri gum. s h o u l d show a disS i n c e k a u r i gum crepancy in results as has been shown to be high as 4 per cent. a complex mixture of varying chemical EFFECTOF TEMcomposition and PERATURE physical properties, A 20-gram mmple depending upon the of 16.6 per cent kauri grade of gum, it was butanol solution was t i t r a t e d a t 65" F. t h o u g h t that some (18.3" C.) w i t h B primary s t a n d a r d petroleum lacquer solcapable of accurate vent until the end point reproduction should was reached (when white paper carrying be developed. After 10-point type became considering s e v e r a 1 b l u r r e d and was no substances, t o l u e n e longer legible), and and n-heptane weie the res u I t recorded. It was then allowed t o selected as being warm u p t o 73" F. most suitable. Both (22.8' e.),additional of t h e s e are s t a b l e BETWEEN TOLUENE-HEPTANE RATIO(TOLUENE s o l v e n t added until FIGURE 5. RELATION substances; they may NUMBER) AND KAURI BUTANOL VALUE the solution c 1o u d e d
September15,1933
INDUSTRIAL AND ENGINEERING CHEMISTRY
be obtained easily in a c. P. state and are inexpensive enough to be used for standardization purposes. Toluene has a kauri butanol value of nearly 102 and heptane has a value of only 26; thus mixtures of these two will cover the entire range of any ordinary lacquer thinner marketed and used today. Figure 5 shows the curve for the 16.6 per cent solution of bush dial kauri gum, kauri butanol values being plotted against percentages of toluene in a toluene-heptane mixture. Once such a curve is obtained for any kauri solution, any solvent may be titrated with this solution and then expressed in terms of per cent toluene or toluene number by reference to this curve. I n this way, variations due to differences in kauri solutions will be eliminated and a standard value obtained which should be easily reproducible in any laboratory, provided other points, such as the amount of kauri solution used and the temperature of test, are standardized. The authors propose that the kauri butanol solution become a testing medium only, standardized by a primary standard, the toluene-n-heptane blend. The solvent power of a paint and lacquer solvent will be expressed in comparable and re-
309
producible toluene numbers. A similar method of using a primary standard (isooctane and n-heptane blend) has been adopted and successfully used by the petroleum and automotive industries for determining the antiknock value of gasolines since 1929 (5).
(1)
BIRLIOGRAPHY Am. Paint Varnish Mfrs. Assoc., Sci. Sect., Circ. 313,390 (1927).
(2) Ibid., Circ. 318,492 (1927). (3) Edgar, G., IND.Eao. CHEM.,19, 145 (1927). (4) Fauser, E., Am. Paint Varnish Mfrs. Assoc., Sci. Sect., Circ. 291, 275 (1926). ( 5 ) Hosking, J. R., Rec. trav. chim., 48,622-36 (1929).
Paint Varnish Mfrs. Assoc., Sci. Sect., Circ. 319,595 (1927), (7) Paint and Varnish Superintendents' Club., Am. Paint Varnish Mfrs. Assoo., Sci. Sect., Circ. 378, 145 (1931). (8) Stewart, J. R., Ibid., Circ. 378, 143 (1931). (6) Kiehl, S. R., Am.
RECEIVED May 17, 1933. Presented before the Division of Paint and Varnish Chemistry at the 85th Meeting of the American Chemical Society, Washington, D. C . , March 26 to 31, 1933.
Effect of Certain Preservatives on the Determination of Sucrose by the Invertase Method N
CHARLESF. POE,MARYCOOLEY,AND N. F. WITT D e p a r t m e n t of Chemistry, University of Colorado, Boulder, Colo.
K
JELDAHL in 1881 (6) proposed the use of invertase in lieu of hydrochloric acid as a hydrolytic agent of sucrose for use in the Clerget method. The first investigators to apply invertase t o the determination of sucrose in food products appear to be Ling and Baker (8) who used the enzyme to analyze molasses and other sugar products. Invertase is replacing hydrochloric acid for the inversion of sucrose because the former is more selective, having no effect on a number of acid-hydrolyzable substances of the nonsugar group. Since invertase is susceptible to a number of chemicals which retard or prevent its action, it was decided to investigate the effects of different food preservatives on the determination of sucrose by the invertase method. The effects of the common food preservatives, other than alcohol (1, 5 , IO), on the determination of sucrose have been little investigated, although a number of studies have been conducted relating to the effects of preservatives and other chemicals upon the enzyme before it has been used as a hydrolyzing agent for sucrose, including the researches of Euler and coworkers (2, 3, d ) .
thought advisable to test the particular sample of invertase preparation used in this research-for the optimum pH. The results are presented in Table I, which shows that the activity was fairly satisfactory for pH values from 3 to 6. The most efficient pH, however, was between values of 4 and 5. TABLEI. EFFECTOF PH TIME p H 3 Min. 0 5 15 25 40 60
ON ACTIVITY OF INVERTASE (10 grams sucrose per 100 cc.) P H 3.5 ~ H 4 . 0~ H 4 . 5P H 5.0 ~ H 6 . 0~ H 7 . 0~ H 8 . 0
38.5" 3 8 . 5 38.5 38.5 38.5 38.5 38.5 23.7 27.6 36.6 27.1 2 7 . 6 2 5 . 3 23 6 7 . 6 7.2 7.3 9 . 3 32.0 8.5 9.0 0.6 0.8 0.4 2 . 8 27.2 2.5 2.3 3 . 1 22.3 2 . 9 2 . 7 2 .0 -1.0 -1.2 -6.1 16.1 -5.8 -5 6 - 5 . 2 -4.8 -5.0 10.1 7 . 6 7 . 0 7 . 6 7 . 7 -7.0 -7.2 80 -9.4 -9.5 -9.6 -8.9 5.1 -9.3 -9.0 120 1 1 . 0 1 1 . 0 1 0 . 1 1.0 1 1 . 1 1 0 . 2 1 0 . 4 300 -11.2 -11.3 -11.2 -11.3 -11.3 -10.8 600 - 1 1 . 3 0 Polariscope readings, 200-mm. tube.
38.5 38.3 37.0 35.2 33.0 30.1 27.4 22.1 2.1 -6.8
Different amounts of the various preservatives were added to sucrose solutions and the rates of inversion were determined with invertase. The pH of each solution, excepting those to which formaldehyde was added, was adjusted with PROCEDURE acetic acid or sodium hydroxide to a value between 4.5 and 5. Ten-gram amounts of sucrose were weighed into 100-cc. flasks No alkali was added to the flasks containing formaldehyde and dissolved in about 70 cc. of water, the desired amount of because the preservative would have been changed; the pH preservative was added, and the pH was adjusted. The invertase value for the 0.1 per cent solution was 4.5 and for the 4 per was added, and the volume was made up t o 100 cc. The polari- cent solution, 3.25. The rates of hydrolysis for sugar soluscope reading was taken immediately and like readings were made at stated intervals, the temperature being kept at 25" C. tions containing the various preservatives, as compared to a As each portion was removed, a small amount of alkali was control containing no preservative, are given in Tables 11, added t o stop the action of the invertase and to complete the 111,and IV. mutarotation. Complete inversion did not take place with the sugar According to Nelson and Bloomfield (9) the optimum pH solutions containing certain preservatives. It therefore for the action of invertase is between 4.5 and 5. It was remained to be determined whether or not this retardation
