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the permission granted by the officials of the Northwest Paper Company to include these data in the present paper. Without their wholehearted coiiperation this study could not have been completed for publication.
Literature Cited Aronovsky, S. I., U. S. Patent 2,037,001 (April 14, 1936). Aronovsky, S. I., and Gortner, R. A., IND. E s G . CHEM.,22, 264 (1930).
Ibid., 22, 941 (1930); 25, 1349 (1933); 26, 61, 220 (1934). Ibid., 27, 451 (1935). Engel, O., and U'edekind, E., German Patent 581,806 (-4ug. 3, 1933). Higglund, E., and Urban, H e l m u t , Cellulosechem., 8, 69 (1927); 9, 49 (1928).
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(7) Hibbert, H., and Rowley, H . J., Can. J. Research, 2, 357 (1930). ( 8 ) Kleinert, T., and Tayenthal, K., Z . angew. Chem., 44, 788 (1931); U. S. Patent 1,856,567 (May 3, 1932). (9) M ~ McK., ~ and ~ Gortner, ~ ~R, A , , J ,Phys. Chem., 34, 1509 (1929). (10) Phillips, Max, Chem. Rea., 14, 103 (1934). (11) Rassow, B., and Gabriel, H., Cellulosechem., 12, 227, 248, 290, 318 (1931).
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RECEIVEDAugust 28, 1936. Presented before the Division of Cellulose Chemistry a t the 92nd Meeting of the American Chemical Society, Pittaburgh, Pa., September 7 t o 11, 1936. Published with permission of the director as Paper KO.1443, Journal Series, Minnesota Agricultural Experiment Station. 5. I. Aronorsky was Cloquet Wood Products Fellow, University of Minnesota; the fellowship wae established by the Northwest Paper Company of Cloquet, Minn. At present he is Resident Fellow of the Sorthwest Paper Company a t the Institute of Paper Chemistry, Appleton, Wis.
Germicidal Action of Benzylphenols
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r\' THE past few years considerable information has appeared in the literature concerning high-coefficient germicides, which show phenol coefficients ranging from 10 or 20 u p to values as high as 2000. The investigation of germicides of such high potency has proved attractive. By their use it is possible to conceive of new types of antiseptic solutions which possess a high killing power against disease organisms and a t the same time are free from the faults of the older phenolic diainfectants, such as odor and causticity. In many of the studies reported on these high-coefficient germicides, an attempt has been made to correlate killing power with chemical structure. The reasons for such an attempt can readily be understood, since organic research workers have for years been correlating chemical structure with purely phyqical properties such as viscosity, index of refraction, etc. However, in dealing with killing power upon microorganisms, we are dealing with a biological phenomenon which can be measured only by selecting certain standard conditions for the measurements. The need for suck standardization in determining the phenol coefficient was early recognized by bacteriologists and has resulted in the adoption of three technics: the Rideal Walker (R. W.) method; the standard used in England, the Hygienic Laboratory method (H. L.) ; and the Food and Drug Administration (F. D. A.) method, ahich is standard in the United States. Since American conditions are dealt with here, the F. D. A. method is considered in connection with the phenol coefficient. Reddish ( 7 ) recently pointed out that the phenol coefficient is readily reproducible when the standard conditions of 'the technic are rigidly observed. The more important conditions are : 1. Use of Bacillus lyphosus as the test organism. The strain selected is killed by phenol in a concentration of 1:90 in 10 minutes but not in 5 minutes under the standard conditions. 2. A test temperature of 20" C. 3. Dilution with water of the germicide to be tested.
The phenol coefficient technic was originally developed for testing phenolic or cresylic germicides prepared for use by the ultimate consumer. That is, the germicides for which the test was intended were either water-soluble or were emulsified in such a way that they could readily be diluted in water and thus observe the standard conditions of the test.
Effect of Formulation with Sulfonated Oil T. S.CARSWELL AND J. A. DOUBLY Monsanto Chemical Company, St. Louis, Mo.
A serious departure from the standard test occurred when recent investigators tried to measure the phenol coefficient of high-potency germicides. These germicides differ radically in chemical composition and physical nature from the phenols and cresols for which the test was originally proposed. The most important deviation lies in their low water solubility. I n many cases the water solubility is so low that it is impossible to obtain an aqueous solution which can be diluted in the phenol coefficient test and still retain killing power. As a result, some investigators resorted to the use of alcohol or sodium hydroxide to retain the high-molecular-weight phenols in solution. The result was that figures were obtained which may not accurately represent the phenol coefficients of the materials in question, depending upon the quantity of solubilizing agent added and its effect either upon the microorganisms or upon the germicidal properties of the phenol itself.
Recent publications indicate the germicidal and fungicidal value of benzylphenols and their substitution products. I n this paper the effect of formulating benzylphenols with sulfonated oil is described. The facts presented are of theoretical interest since previous investigators i n the field of high-potency germicides frequently have considered only the germicidal power as determined in dilute aqueous or aqueous-alcoholic solution. Such solutions have little practical sig-
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This objection is serious even if we consider that the investigators were only trying to obtain some kind of empirical relation between chemical constitution and killing power. The objection becomes more serious if we consider that the ultimate aim of such work is not purely scientific, but has for its commercial objective the formulation of better and more powerful disinfectants, In general, it is impractical t o use these high-potency germicides either by themselves or in the very dilute aqueous solutions which represent their solubility limits. To be practically effective, these products must be formulated in such a way that the average layman can use them with success. This means that they must be solubilized so that they can be readily diluted with water. Various means have been employed, such as solution in caustic soda, emulsification (either through a chemical dispersing agent or through mechanical means such as the colloid mill), or solubilization by admixture with sulfonated oil, soap, or other dispersing agents. Previous investigators pointed out that such treatments have a marked effect upon the germicidal power of the products (3-6, 9, 10). For some time the present writers have concentrated their efforts upon that group of highcoefficient germicides embraced by the benzylphenols and their alkyl and halogen substituents. These compounds are effective against most types of microorganisms, and certain members of the series are little influenced by combination with the solubilizing agents needed to give useful formulations.
Germicidal Activity That the benzylphenols and their substitution products possess considerable germicidal activity has been known for some time. Klarmann (1) studied 4-hydroxydiphenylmethane (p-benzylphenol) ; he gives the phenol coefficient against Bacillus typhosus (using the H. L. method) as 4.6. Schaffer and Tilley (8) give the phenol coefficient of p-benzylphenol against Bacillus typhosus strain No. 1 (using a modified R. W. method) as 62. Klarmann ( 2 ) gives the phenol coefficient for 2-benzyl-Pchlorophenol against Bacillus typhosus as 71.4 and Staphylococcus aureus as 200; the F. D. A. method was employed but the tests were made a t 37” instead of the standard 20’ C. prescribed for general disinfectants. Klarmann, Gates, and Shternov (3) studied halogen derivatives of monohydroxydiphenylmethane (benzylphenol) and reported phenol coefficients against a number of organisms for a variety of compounds. I n order to obtain solutions, varying proportions of alcohol were employed. Sulfonated oil has been used for preparing germicidal solutions for some time. Owing to the relative insolubility of the benzylphenols, a sulfonated oil was selected which would disperse the products when a relatively small quantity of oil was
nificance since high-coefficient germicides cannot, in general, be applied in simple formulations. There is a wide variance in the behavior of closely related members of the benzylphenol series when dispersed in sulfonated oil, although the general effect of such formulation is to decrease the phenol coefficient. By plotting phenol coefficients against concentration of sulfonated oil, it is possible to obtain a “theoretical phenol coefficient” for aqueous solutions of germicide.
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FIGURE 1. PHEA-OLCOEFFICIENT MEASUREMEXTS AQAINST Two MICROORQAXISMS
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used in proportion to the germicide present. Even with this selected grade of oil, dispersion with a relatively low ratio of oil to germicide could be obtained only with certain members of the benzylphenol series. When two parts of this oil were mixed with one part of 0- or p-benzylphenols, a clear solution resulted. Upon dilution of this clear solution with water, a uniform dispersion of the germicide was obtained. This dispersion showed a marked Tyndall effect, indicating that the germicide particles were colloidally dispersed. When a larger proportion of sulfonated oil was taken, the dilution solutions showed less and less of the Tyndall effect as the degree of dispersion became greater. With o-benzyl-p-chlorophenol, p-benzyl-o-cresol, and p-benzyl-o-chlorophenol, three parts of sulfonated oil were required to give dispersion on dilution. No dispersion could be obtained with o-benzyl-ocresol or o-benzyl-o-chlorophenol.
Phenol Coefficient Measurements Figure 1 and the following table show the results of phenol coefficient measurements against Bacillus typhosus JHopkins strain), using varying ratios of sulfonated oil to germicide; all measurements were made by the F. D. A. method at 20 O C. : --Ratio,
Benzyl Compound o-Benzylphenol p-Benzylphenol o-Benzyl-p-chlorophenol p-Benzyl-o-cresol p-Benzyl-o-chlorophenol
1:2 58 42
... .... ..
1:4 44 31 3.1
