Table IV. Precision of Column Chromatographic Method
Acids Determined Saturated Total monoenic cis Monoenoic trans Monoenoic Total polyenoic cis, cis Polyenoic cis,trans Polyenoic
Acids Found, yo Std. Mean Range dev. 16.15 0.12 0.04 53.40 0.42 0.18 36.42 1 . 2 1 0.51 16.98 0.96 0.37 30.45 0.53 0 . 2 1 25.49 0 . 5 4 0.21 4.96
0.69
0.27
was subtracted from the cis.cis value obtained chromatographically. Although generally &,trans in nature, small amounts (591, or less) of conjugated dienes are believed not to interfere with and not to be measured by the infrared trans band at 10.3 p since conjugated trans double bonds absorb a t shorter wavelengths (about 10.1 p ) . Thus, they would be included in the cis& value obtained b y difference in the chromatographic method. The conjugated dienes are not measured b y the enzymatic method and hence a correction is in order t o arrive a t a basis for comparison. The reasonable agreement indicated b y the data in Table V is in accord with the assignment of a cis,trans rather than a trans,trans configuration to the polyunsaturated acids in hydrogenated samples, since expressing the infrared results on a trans,trans basis would have resulted in much higher cis,& levels for the chromatographic method. Pub-
lished data (18) also indicate that the trans polyenoic isomers in hydrogenated fats are predominantly cis,trans dienes. The column chromatography of the mercury derivatives is applicable to much smaller quantities than the usual fractional crystallization or countercurrent distribution methods. High purity (>97%) cuts of saturated, monoenoic, and polyenoic acid species are isolated, suitable for further chemical, infrared, gas chromatographic, or double bond distribution (oxidative cleavage) analyses. No difficulty is experienced in separating such troublesome pairs of species as palmitic-oleic and myristic-linoleic. The use of this method in following the hydrogenation of fats and oils should result in a clearer picture of the changes occurring during hydrogenation than has been available to date. LITERATURE CITED
(1) Callen, J. E., Pace, Z. T., ANAL. CHEW30, 2066 (1958). (2) Chatt, J., Chem. Rev. 48, 7-43 (1951). (3) Inouye, Y., Soda, M., Hirayama, O., J . Am. Oil Chemists’ SOC.32, 132-5 (1955). (4) Janben, E., Andreas, H., Angew. Chem. 70, 656 (1958); Chem. Ber. 92, 1427-35 (1959); Chem. Ber. 94, 628-33 (1961); Fette, Seifen, Anstrichmittel 63, 685-8 (1961). . ‘ (5) Kauffman, K. L., Lee, G. D., J . Am. 0 2 1 Chemists’ SOC. 37.385-6 (1960). (6) Kaufmann, H. P., Feite, heifen, Anstrichmittel 5 8 , 492-8 (1956). (7) Kaufmann, H. P., Schurnbusch, H., Ibtd., 60, 1046-50 (1958). (8) Kishimoto, Y., Radin, N. S., J . Lipid Res. 1, 72-8 (1959). (9) Kuemmel, D. F., J . Am. Oil Chemists’ SOC.35, 41-5 (1958).
Table V. Comparison of Column Chromatographic and Enzymatic Results for Polyunsaturated Acids
Enzy-
mat- Chromatographic ic (cis, (cis,& minus Sample cis) Conjugated Dienej Cottonseed oil 55 55.9 - 0 . 4 = 55.5 Partially hy- 24 25.5 - 1 . 6 = 23.9 drogenated soybean oil Partially hy14 17.4 - 1 . 2 = 16.2 drogenated soybean oil Partially h 1s 18.6 - 1 . 3 = 1 7 . 3 dr ogenateJsoybean oil Conventional 8 9.9 - 0 . 1 = 9.8 shortening
(10).Landomne, It. A., Lipsky, S. R., Bzochim. Biophys. d c t u 46, 1-G (1961). (11) Li sky, S. R., Landome, R. A.,
Lovegck, J. E., A s . 4 ~ . CHEW 31, 852-6 (1959). (12) MacGee, J., Zbzd., 31,298-302 (1959). (13) Mangold, H. IC., Kammereck, R., Chem. Znd. (London)1961, 1032-4. (14) Quinlin, P., Weiser, H. J., J . Am. Oil Chemists’ SOC.35, 325-7 (1958). (15) Sallee, E. M., ed., “Official and Tentative Methods of the American Oil Chemists’ Society,” 2nd ed., Method L 12a-55. American Oil Chemists’ Society, Chicago, Ill. (16) Schmidt, G., Saturwiss. 45, 41 11958). (17) Scholfield, C. R., el al., J . Am. Oil Chemists’ SOC.38, 208-11 (1961). (18) Sreenivasan, B., Brown, J. B., Ibid., 33,341-4(1956). RECEIVED for review February 23, 1962. Accepted May 14, 1962.
Manometric Determination of Active Hydrogen by Reaction with Diborane FRED E. MARTIN and RAYMOND R. JAY Chemical Products Division, Aerojet-General Corp.,
b A simple and rapid manometric procedure for determining active hydrogen in organic materials has been developed based upon the evolution of hydrogen from a solution of diborane in tetrahydrofuran. The method is applicable to a wide variety of materials, but is especially valuable for hydroxyl group determinations of nitro alcohols, epoxy compounds, and sterically hindered hydroxyl compounds not amenable to analysis b y the various anhydride or acid chloride esterification techniques. Precision of is obtained. about 1
yo
T
AZUSU, Calif.
common titrimetric methods for determining hydroxyl groups inelude acetylation (6) or phthalation (8) in pyridine. Gasometric methods for active hydrogen generally involve measurement of gases evolved in reactions with lithium aluminum hydride (4)or a Grignard reagent such as methyl magnesium iodide (6). Fritz and Schenk (3) described a perchloric acid catalyzed acetylation in ethyl acetate or pyridine which extends the scope of the acetylation procedures to include many sterically hindered hydroxyl groups while greatly decreasing the time HE
required for analysis. Stetzler and Smullin (3) substituted p-toluenesulfonic acid for the perchloric acid showing good results for polyether diols and unsaturated compounds attacked by the perchloric acid reagent. However, no method has proved entirely satisfactory for analysis of the many diverse types of frequently encountered hydroxy compounds. For example, certain nitro functions constitute direct interferences with the LiAlH4 and Grignard methods (Table I), while the instability and acidic nature of many of these compounds preclude VOL. 34, NO. 8, JULY 1962
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use of the titrimetric acetic or phthalic anhydride procedures. Furthermore, the oxirane ring interferes m t h hydroxyl group analysis by acetylation, phthalation, and Grignard techniques, whereas certain sterically hindered or tertiarj-
Table 1. Apparent Active Hydrogen Values of Nitro Compounds
Active Hydrogens per Mole Grignard Li.$lH, DiCompound ( 6 ) b borane iiitroniethane 0.83 2.40, 2.75 . . . Kitroethane 0.93 ... ... 1-Sitropropane" 0.68 ... 0.02 2.08 ... Kitrobenzene . , . 2-Nitropropane" ... ... 0.02 The values given for the diborane method were not corrected for water. The small values obtained may well be ascribed to the water contents of the samples. Data taken from references cited. Table II.
Active Hydrogen Values by Diborane Method
Compound 2-Bromo-P-nitro-1,3propanediol 2-Chloro-2-nitro-1,3propanediol 2-Chloro-2-nitro-1propanol 3,3-Dinitro-1.5pentanediol 2,2-lkiitro-1,3propanedial 2,2-Dinitropropanol 2-Ethyl-2-nitro-1,3propanediol ~ - Hdroxymethyl-5T ni tro-2-phenyl1,3-dioxan 5-Hydroxymethj l-5ni tro-2-( n-propyl )1,3-dioxan l,I,l-Trinitroethanol 2-Methyl-2-ni t ro- 1propanol tris-Hydroxymethylnitroniethane Water bis-Phenol A Triphenylsilanol ( Dow-Corning Lot P-375 (Purified Gradej 5,5-L)initro-1,2hexanediol
-4rtive Hydrogens per Mole 2.01, 2.02 1.99, 1.99 1.03, 1.02 1.97, 2.00, 1.99 2 . 0 1 , 2.01, 2 . 0 2
1.02, 1.01 2.01, 2.01, 1.98 1.00, 1.00 0.99, 1.01 0 . 9 7 , 0.98
1.01, 1 . 0 1 3.07, 3.05 2.01, 2.05, 2.05 2.03, 2.05 0 91, 0 95 (0.14 by Ac:O) (4) 2.01, 2.02, 1.97, 1.97, 2.00, 2.01, 2.01, 2.02, 2.01, 2.02, 2.01 1 , 9 6 , 1.92 0.99, 0.98
2-Mercaptoethanol Benzoic acid, U. S. Bureau of Standards n-Butyl nitrate 0.00 Dimethylnitramine 1.44 Epon 815 (Sample 2) Epon 828 (Sample 1) 0.67, 0 . 6 4 , 0.65 0.94, 0.92 Epon 828 (Sample 2) 1.22, 1.21, 1.19, 1.21 Epon 828 (Sample 3) Epirez 5071 0.72. 0 . 7 2 , 0.73 Eaon 820 0.74: 0.77: 0.77. 0.76 4.12; 4.06; 4.15;4 12 Epon 812 Epirez 510 0.84, 0.85, 0.89, 0.86 Alkyl epoxy stearate (KP-90) 0 . 4 5 , 0.46 Alkyl epoxy stearate (KP-90) plus added poly(buty1ene ether glycol) 3 . 0 9 , 3.15 Polypropylene glycol 1.86, 1.84 Commercial polyolsc 2.94, 2.86 Polyglycidyl nitrate 4.06, 4.12, 4.09, 4.21, 4.18 4 a Calculated on basis of known values. b By phthalic anhydride. c A commercial mixture of polyether and polyester diols containing epoxy compounds and an aromatic secondary amine. d Based upon infrared studies of reaction with isocyanate. I
rapidly reduced by diborane at room temperature, and esters are slowly reduced to produce dialkosy boranes ( I ) . However, no interference is encountered because hydrogen is not evolved. This is verified b y the data presented in Table I1 for cyclopentanone. The slight hydrogen evolution actually found is attributed to water. In the diborarie analysis of organic hydroxyl groups, water and carboxylic acids are direct stoichiometric interferences. However, correctioiis are easily made based upon separate water and acid analyses of the sample by conventional techniques. \17ater reacts in the presence of excess diborane to give two moles of hydrogen per mole. Euperimental verification was obtained in triplicate determinations giving values of 2.01, 2.05, and 2.05 moles of hydrogen per mole of miter. X sample of benzoic acid (U.S. Bureau of Standards) was found to evolve 0.98 and 0.99 mole of hydrogen per mole. It is interesting to note that alkyl amines do not cvolve hydrogen in the diborane method and hence do not interfere as long as sufficient excess diborane is present. A sample of isobutylainine was found to evolve essentially no hydrogen (0.02 mole per mole of amine). Under the test conditions apparently stable, amino boranes are formed ( 2 ) . This fact suggests a useful technique for analysis of mixed amines and alcohols. The diborane method gives only the alcohol while the Grignard reagent gives the sum of amine plus alcohol. The amine may also be determined alkalimetrically. Hydrazine and sym-dimethylhydrazine are reported (7) to form crystalline adducts with diborane. Although i t has not been tried, i t appears t h a t the hydrazines will not evolve hydrogen in the present diborane procedure. This
suggests the possibility of using the diborane technique for determining the water content of hydrazine and its homologs, n-hich cannot be satisfactorily analyzed by the usual Karl Fischer mater methods. The reaction with diborane of less basic or weakly acidic-SH groups such as amides, imides, pyrroles, and sulfonamides has not been investigated but i t appears probable that the more acidic species n ould evolve hyl-lrogen. ACKNOWLEDGMENT
The authois express their gratitude to Aerojet-General Corp. for peimission to publish this work and extend their appreciation to N. H. Simpkins and R. J. Bloomfield for their suggestions and for conducting many of the analyses reported in this paper. LITERATURE CITED
il’i Brown. H. C.. Schlcsinger. H. I , Burg, A. B., J.’ilm. Ch&. ’Soc. 61, \
,
673-80 (1939). (2) Callery Chemical Co., Tech. Ruii. C-020, March 1958. (3) Fritz, J. S., and Schenk, G. H., ASAL. CHERI. 31, 1808-12 (1959). (4) Higuchi, T., “Organic Analysis,” I1 (J. Mitchell, Jr., I. 34. Kolthoff, E. S. Proskauer, A. Weissberger, eds., pp. 123-67, Interscience, New York, 1934. (5) Kharasch, M. S., Reinmuth, O., “Grignard Reactions of h’on-metallic Substances,” p. 1166, Prentice-Hall, Kew York, 1954. (6) Ogg, C. L., Porter, IT. L., Willets, C. 0.. IND.ENG.CHEM..ANAL.ED. 17. 394 (1945). (7) Schlesinger, H. I., Steindler, M. J., J . Am. Chem;,Soc. 75,756 (1953). (8) Siggia, S., Quantitative Analysis via Functional Groups,” 2nd ed., p. 12, Kiley, h’ew York, 1968. (9) Stetzler, R. S., Smullin, C. F., AXAL. CHEY.34, 194-5 (1962). RECEIVEDfor review hlarch 9, 1962. Accepted hlay 14, 1962. Contribution No. 234 from the Aerojet Chemical Products Division. VOL. 34, NO. 8, JULY 1962
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