Rapid Color Test for Detecting Certain Long Chain Diamines in the Presence of Monofunctional Long Chain Amines
SIR: Few literature references are available for the specific determination of diamines in the presence of amines (1, 2 ) . The examples given are generally for shorter aliphatic or aryl dianiinw with no mention of the longer chain diamines. The present paper is concerned with determining qualitatively diamines of the general formula R-SH-(CH2)3-llH2 where “R” represents an alkyl group of C-Cla caibons. Diamines of this type have found wide industrial application in the fields of asphalt, germicides, flotation, plastics, water treatment, and petroleum. .Is the structural formula indicates, these compounds contain both primary and secondary amine groupings and are, therefore, strong organic difunctional bases. Long chain diamines can be separated and identified in the presence of other amines by thin layer and gas chromatography ( 5 ) . Even though the methods are most acceptable, they do require an appreciable period of time, and a more rapid method of classification is always desirable. Using the described procedure, a qualitative analysis can be performed in a matter of minutes. The use of quinhydrone as a coloriniet,ric reagent for determining amines has been reported by several authors (3, 4). It has also found use as a colorimetric reagent in determining amino acids ( 6 ) . 13y using carbon tetrachloride as a solvent instead of an alcoholic solvent as suggested in previous publications, it was found possible to detect the specific long chain diamine in the presence of monofunctional long chain amines. EXPERIMENTAL
Reagents. Carbon tetrachloride and methanol were reagent grade. Quinhydrone was obtained from Eastm a n Organic Chemicals and used in pieparing a 2.5% solution in ni hanol. Heating is necessary t o obtain a iolution rapidly. This reagent 1- stable for several months if stored in a dark place, b u t it is advisable to iireiiare a fresh solution monthly. Procedure. Add 5 nil. of carbon tetrachloride t o a te?t tube. Dissolve approximately 5-25 nig. of sample into t h e carbon tetrachloride, heating if necessary t o obtain a solution. Cool t o room temperature and add 0.1 ml. of quinhydrone solution. Shake well. X po-itive test for a diamine is indicated b y t h e almost immediate I
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Table 1.
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Determining Presence of Long Chain Diamines in 12 Amine Solutions
Color of test Very light yellow solution Very light yellow solution Dark red solution Very light yellow solution Dark red solution
Results of test Segative Negative Positive Segative Positive
Gold
Negative
Dark red solution Very light yellow solution
Positive Negative
Gold
Negative
10. S,.~-dimethylmyristylamiIie S-cocopropaiiediamine-1,3 1 1 . Tallo\\ amine 12. Tallol\ amine S-oleylpropanediamine-1,3
Dark red solution
Positive
Gold Dark red solution
Negative Positive
appearance of a dark red solution. T h e maximum color development is reached in 2 minutes.
methylene chloride, were investigated. S o n e of these produced an immediate positive test, but upon standing, a positive test was indicated after 10 minutes in chloroform, and in 15 minutes for methylene chloride. It is apparent then that the rate of reaction is dependent to some extent on the quantity of chloro-substitution on the methyl group. .It the present, the nature of the colored product has not been studied by these authors, but a possible series of reactions has been suggested by Usova (6) in determining w-aminoenanthic acid by quinhydrone. I t may be likely that a similar chemical mechanism is applicable in the case of these diamines. It is probable that a quantitative determination for long chain diamines could be derived from this specific test, but in most cases the color fades rapidly, and in several instances, had completely disappeared in 10 minutes.
Amine solution 1. 2. 3. 4.
S,S-dimethylmyristylamine
S-methyldicocoamine
~\r-cocoprop~~iediami~ie-1,3
.\--methyldihydrogenatedtallowamine
5 . .\--methyldicocoamine
S-oleylpropanediamine- 1,3 6. Laurylamine S,.\7-dicocopropanediamine-1,3 7. 5-palmitylpropanediamine-1,3 8 , S, -\--dimeth ylt allowamine S,S-dihydrogenatedtallowamine 9. Laurylamine S-methyldicocoamine
RESULTS A N D DISCUSSION
Of the different classes of long chain amines tested, only the diamines react with quinhydrone to give a dark red color. Monofunctional primary amines also react, but give a gold color, while secondary and tertiary amines along with diamine salts do not react a t all. Several diamines of different chain lengths were te3ted. These were commercial products obtained from Armour Industrial Chemical Co. Besides these, three other commercially available long chain diamines (Formonyte 808, hdogen 560, Diam 26 D) were tested, with all of them producing positive tests with quinhydrone and carbon tetrachloride. Table I s h o w results of the test on a number of typical amine solutions. Sample numbers 5 , 6, 8, 9, 10, and 12 are amine mixtures. If the reagent< or the diamine used in the test is not anhydrous, a black floc is produced in a cloudy mixture in place of the expected dark red clear solution. The addition of a few drops of reagent grade isopropanol will make the mixture thoroughly miscible and produce a positive test. Seveial different classes of solvents were investigated in the reaction between quinhydrone and long chain amines. Since carbon tetrachloride was the only solvent of those tested in which a dark red solution appeared almost immediately and specifically in the presence of long chain diamines, other methyl chlorides, chloroform and
LITERATURE CITED
( 1 ) Binder, H., ilngew. Chem. 66, 268 (1954). (2) Farrugia, T’. J., Christopher, P. C., ASAL. CHEM.36, 435 (1964). ( 3 ) Kroller, E., Suddeut. Apoth. Ztg. 90 724 (1950). ( 4 ) Meek, W. F., Entrikin, I. B., J . Chem. Edztc. 41, 420 (1964). ( 5 ) hletcalfe. L. I>.. Schmitz. A. A . J . bas Chromatog., 2,’ 15 (1964). (6) Usova, E. P., Snesarev, K. A., Zh. Analit. Khinz. 19, 243 (1964).
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JOHN R. PELKA LINCOLX D. NETCALFE Armour Industrial Chemical Co. 8401 1%‘. 47th St. McCook, Ill. 60525 VOL. 38,
NO. 4, APRIL 1966
657
