dicator, possesses the advantages enumerated earlier.
addition, they thank Lester McKenzie for making available the alkaloids which wcre used.
ACKNOWLEDGMENT
LITERA1URE CITED
The authors are indebted to Thomas C. Boersig, Joseph R. Simmler, and (1) Conant, J. B., Werner, T. H., J. Am. Chem. SOC. 52, 4436 (1930). Howard W. Ziegler of the Department of chemical Control, ~ ~ l l i ~ ( 2~) Goddu, k ~ R. ~ F., d ~ Hume, D. N., ANAL. CHEM.26, 1679 (1954). (3) &d., p. 1740. Chemical Works, for assisting with the (4) Lange, N. A,, "Handbook of Chemisexperimental work of this paper. I n
try," 9th ed., pp. 1203-4, Handbook Publisbm, 1nc.t Sandusky, Ohio, 19%. (5) Nadeau, G. F., Branchen, L. E., J . Am. Chem. SOC.57. 1363 (1935). (6) Fkilley, C. N., Schweizer, B., ANAL. CHEM.26, 1124 (1954). (7) Seaman, W., Allen, E., [bid., 23, 592 (1951). RECEIVED for review April 22, 1960. Accepted August 15, 1960. Presented in part, Division of Anakytical Chemistry, 130th Meeting, ACS, Atlantic City, N. J., September 19, 1956.
Primary Standards for Titration af Anionic Detergents Using Quaternary Ammonium Halides BENJAMIN VELDHUIS General Chemical Division, Allied Chemical Corp., Morrisfown, N. 1. The alkaline salts of polyhalogenated benzenesulfonic acids have been found suitable for direct standardization of quaternary ammonium halides. These stable sulfonates can be prepared easily.
D
with quaternary ammonium halides is the most widely applied method for assaying anionic surfactants ( 1 , 3 ) . I n spite of gcneral use, present reagcnts for primary standardization of the quaternaries are some\\ hat iriconvenient. Sodium alkarylsulfonate ( I ) is of inexact chemical composition and purity; the corresponding sulfohic acid (3) is hygroscopic. Anotlicr rccommended standard ( b ) , a 0.25% aqueous solution of Aerosol OT (American Cyanamid Co.), the clioctyl ester of sodium sulfosuccinic acid, was found to undergo slow deterioration shortly after preparation. The alkaline salts of polyhalogenated benzenesulfonic acids appear free of these objections. They are relatively easy to prepare and purify, and appear indefinitely stable both as solids and in solution. I n addition, they are pure compounds of known chemical composition. One of these materials, potassium 2, 4, 5-trichlorobenzenesulfonate, is being made commercially available (Baker and Adamson Division, Allied Chemical Corp.). IRECT TITEATION
EXPERIMENTAL
Preparation of Reagents. Exactly 363 grams of lJ2,4-trichlorobenzene, practical grade, were placed in a threenecked laboratory reaction flask equipped with dropping funnel, mcchanical agitator. thcrmometer, and piovision for extcrnal cooling arid Iicxting Then 168 grmis of stabilizrri
liquid sulfur trioxide, Sulfan (Baker and Adamson Division, Allied Chemical Corp.), were added dropwise over 18 minutes. The temperature rose spontaneously to 105" C. and was held there by slight cooling. After addition of the trioxide, the dropping funnel was replaced by an azeotrope trap; 500 ml. of water were added and the mixture was refluxed with stirring for 2 hours to distill 23 ml. of unreacted starting material. The warm solution was then filtered to give 1337 grams of acid solution. A 668-gram portion of the acid solution was neutralized with 17% aqueous potassium hydroxide, cooled to room temperature, filtered, and washed with cold water to give the crude potassium sulfonate. The 403 grams of wet cake --ere redissolved in 3.5 liters of distilled water a t 95" C.; the solution was filtered hot to remove suspended solids, cooled, and refiltered. The product was airdried to constant weight, 157 grams. The other sulfonates w r e prepared similarly from the corresponding halogenated benzenes. Analytical and
Table I.
Analytical Data for Standard Sulfonates
Hydration, >foles
S o . Benzenesulfonate 1 4-Bromo 2
3
2,4,5-Trichloro 2,4,5-Trichloroc
4
2-Bromn-5-
.5
6
chloro 2,5-Dibromo 2,4,5-Trihromo
titration data are given in Table I. The degree of hydration shown for sulfonates 1,2, 5, and 6 are in agreement with the literature values (4); salts 3 and 4 are new, although the sulfonic acids are known (4). None of these sulfonates has been prepared previously using liquid sulfur trioxide. The solubilities of salts 2, 4, and 6 in water at room temperature are approximately 0.9, 3.0, and 0.8 grams per 100 grams of solution, respectively. At 95" C., the corresponding figures are a p proximately 6, 12, and 7 grams per 100 grams of solution. The theoretical molecular weights in Table I were arrived a t by determining the water content and assuming the sulfonates to be pure as indicated by halogen and sulfur analysis. Originally chloride determinations were used to determine the Hyamine 1622 concentration. Since this method was not completely satisfactory, salt 2 became the usual standard. The water was determined by the Karl Fischer titration; the halogen by
Water Sone None 15
Molecular Wt. Theo. Founda 275 33Ob 300
310
Halogen Found
300 312 326
Tho. 29.0 35.4 34.3 26.4 43 0
1 0
328
1 0 1 0
372
374
451
149
53 1
Sulfur
Theo.
Found
28.9
11.6
34.6
10.3
11 3 10.7 0.7
42 6 .5Z 1
8 6 7 1
8 1 6.8
35.8
26 6
10.7
By titration with rtmdardized Hyamine 1622 (diisohutyl phenoxy cttiosy ethyl clirwttiyl bt~iizylanirnonirim chloride, monohydrate). End point w r y iiidistirict. Sotliiim d t used; all others were potassium ssirs.
VOL 32, NO. 12, NOVEMBER 1960
1681
Parr bomb followed by Volhard titration; and the sulfur by Parr bomb, fol-
to sulfonic acids of molecular weight about 250 and less.
lowed by gravimetric determination of
BaSO4 Analytical Application. The quaternary salt employed was Hyamine 1622 approximately 0.0055M solution. A typical Standardization was per-
(a,
formed as follows: Dissolve 3.954 grams of potarsium 2,4,5-trichlorobenzenesulfonatein water to 500 ml. of total solution. Titrate 5 ml. of this solution as detailed in the House and Darragh (3) modification of Epton’s (2) procedure with 24.4 ml. of the quaternary solution. Normality = (sample weight) (1OOO) (aliquot) (molecular weight) (ml. Hyamine 1622)
-
DISCUSSION
The sulfonates were stable at least a year at room temperature, both in solid form and in water solution. The potassium salts were favored over sodium merely because the former were more fully described in the literature (4); as noted above, the former are less soluble in water. The series of five sulfonates of ascending molecular weight was prepared to permit standardization at various desired points over the usual commercial range of water-soluble surfactants (3). In general agreement with others (I, 3), the present study shows the quaternary titration procedure to be inapplicable
ACKNOWLEDGMENT
The author acknowledges the assistance of E. E. Gilbert in preparing this paper. UTERATME CITED
(1) American Society for Testing Materials, Philadelphia, Pa.,
ASTM Stand-
=&,D 1681-592’, Pt. 10, p. 276,1959. (2) Epton, S. R., Tram. Faraday Soc. 44,226 (1948). (3) H o w , R., Darragh, J. L., ANAL. CHEY. 26,1492 (1954). (4) Prager, B., et al., e&., “Beilateins Handbuch der Organischen Chemie,”
J Y ed., Vol. XI,Berlin, Sprinqr, 1928..
(5) Rohm and Haaa Co., Phdadelph, Pa., Tech. Bull. SANaO,1954.
RECEIVED for review February 18, 1960. Accepted July 7,1960.
A Classification Test for Alkyl Halides RALPH L DANNLEY and FRANK V. KITKO Morley Chemical laboratory, Western Reserve University, Cleveland, Ohio ,Treatment of alkyl halides with sodium nitrite in a dimethylformamide solution containing urea yields the corresponding nitroparafins of the primary and secondary compounds. After addition of aqueous sodium hydroxide and carbon tetrachloride, acid is added dropwise to produce the red nitrolic acid salt from the primary nitroalkane, a blue-green pseudonitrole from the secondary compound. The test distinguishes primary and secondary alkyl halides through octyl, and most cycloalkyl halides. It is not applicable to benzyl or allyl halides, cyclohexyl chloride, or most difunctional compounds. Sodium nitrite in dimethyl sulfoxide provides an even more sensitive test with some alkyl chlorides and many bromides and iodides. Unfortunately, an interfering color develops with tertiary bromides and iodides which makes the solution undesirable for general test purposes.
T
HE only tests included in the common organic qualitative analysis texts to classify alkyl halides are of limited utility. Alcoholic silver nitrate is primarily applicable only to chlorides and even then does not differentiate between primary and secondary chloroallcanes. The less common sodium iodide in acetone test gives a partial Merentiation of primary, secondary. and tertiary alkyl bromides and chlorides but is useless with alkyi iodides. Meyer, as a consequence of his re-
1682
ANALMICAL CHEM!STRY
search on nitroles and pseudonitroles, proposed a sequence of reactions to classify‘alcohols(4). First, the alcohols were converted to the iodides using phosphorus and iodine. Next, the iodides were heated with silver nitrite to form the nitroparafKns. Finally, by nitrosation, the primary nitroalkanes were converted to reddish tan salts of nitrolic acids, the secondary nitroalkanes formed blue pseudonitroles, while the tertiary nitroalkanes were unchanged. This was called “the red, white, and blue test for alcohols.” The simplicity of the nitrosation step has resulted in the continued use of this portion of the procedure as a classification test €or nitroparaffins. The Meyer procedure has not been used as a classification test for alkyl halides in general because of the quantities of reagents needed and the limitation that only some of the more reactive halides, usually primary bromides or iodides (3),give satisfactory tests. Kornblum ( I ) and his coworkers have recently reported that alkyl halides react with sodium nitrite in dimethylformamide or dimethyl sulfoxide solution t o form nitroparaffins. In the present work, the procedure of Kornblum has been adapted together with the nitrosation reaction of Meyer to give a complete classification test for alkyl halides. EXPERIMENTAL
Reagents. The compounds used in testing these procedures were gener-
ally samples of commercial prpducts or the more highly purified compounds sold by chemical supply houses. A few unusual halides were available from other research in progress in the laboratory. No attempt was made t o purify any of these samples further. Special Solution. Dissolve 15 grams of sodium nitrite and 25 grams of urea in 500 ml. of dimethylformamide. Kornblum and his coworkers, in developing the procedure for p r e p aration of nitroparaffins, inhibited a side reaction of oxidation by adding resorcinol or catechol (I). These compounds could not be used in the present work for they give a red color interference in the h d step of acidScation. Procedure Using Dimethylformamide. Place 0.5 ml. of the alkyl halide and 1.5 ml. of a solution of sodium nitrite in dimethylformamide in a test tube. Allow alkyl iodide mixtures t o stand for 20 minutes; place bromide and chloride mixtures in boiling water for 15 minutes. If the alkyl chloride has a boiling point below 100’ C., it will distill and give no test unless a reflux condenser is attached t o the test tube. Next, add 1 ml. of 10% aqueous NaNOz and 2 ml. of 10% NaOH and mix well. Add 1 ml. of CCL and then 1.5 ml. of 10% sulfuric acid drop by drop with shaking. If the aqueous solution turns tan, the halide is a primary type. The reaction mixture sometimes is brownish before adding sulfuric acid. To be a positive test, the color must become more intense on adding acid. (If there is still doubt regarding the tan color, confirmation can be obtained by adding acetic acid until the solution is acid. I n a proper
