ANALYTICAL CHEMISTRY
114 ~
Table I.
~~
~~
Reaction of Commercial Surface-Active Agents to Treatment w-ith Concentrated Sulfuric Acid and Formaldehyde (Continued) rninr
Product Armeen C
Source Brmour
Alkaterge C
Commercial Solvents
RXW2 K--C”
With HiGOa CH20 Beige
+
With HI SO^ Colorless
Chemical Structure“ N-C(CH,) CHzCHgOH
1
Yellow
Light orange
‘0-AH*
Cltrawet K
Atlantic Refg.
Pale yellow
Yellow
Dctergent D-40
Oronite
Pale yellow
Pale yellow
Xacconol N R
S a t l . rlniline
ROSOaXa
Pale yellow
Light orange
Hyponate L50b
Sonneborn
Petroleum sulfonate, oil-free
Dark brown
Brown-hlac k
Yellow Pale yellow Colorless Light orange Orange
Light orange Pale yellow Colorless Orange Red-orange
9
IeeDon T-73 -4ntara OT Am. Cyanamid Du Pont Duponol ME dry Du Pont Duponol LS paste b Aquasol 76AR .4m Cyanamid ” R = alkyl. Dried a t 110’ C. e PEG = polyethyleneglycol. &;os01
’
The color produced with sulfuric acid alone is indicative of the degree of unsaturation present in the nonaromatic molecules. Thus, a petroleum derivative (Hyponate ~ 5 0gives ) brown colors, tall oil derivatives (Renex, Sterox CD, Ethofat 242/25) give red-orange colors, oleic acid derivatives (Emulphors VN-430 and ON-870, ilrlacel C, P E G 400 Dioleate, Ninol 201) yield light orange colors, and saturated compounds (Span 60, Pluronic L62, Ninol 2012A, Armeen C, etc.) produce pale yellow or no colors.
LITERATURE CITED
(1) Davidson, D., and Perlman, D., “A Guide to Qualitative Organic Analysis,” p. 26, Brooklyn, N. Y., Brooklyn College Book-
store, 1952. (2) Gilby, J. A , and Hodgson, H. W., Mfo. Chemist, 21, 4 2 3 (1950). (3) Goldstein. H., Am. Dyestuf Reptr., 36, 629 (1947). (4) Linsenmeyer, K., MeLLiand Teztizber., 21 468 (1940). (5) Wurzschmitt, B., Z . anal. Chem., 130, 105 (1950). 9
RECEIVED for review February 17, 1954.
Accepted July 12, 1964.
Detection of Beta4yd roxyethy lamines by Pyrolysis with Sodium Chloroacetate MILTON J. ROSEN Department o f Chemistry, Brooklyn College, Brooklyn,
B-Llgdroxyethylatnines, upon pyrolysis with sodium chloroacetate, decompose to yield acetaldehyde. The acetaldehyde, when led into a solution of sodium nitroprusside containing diethanolamine, produces a blue color which mag be used as a qualitative test for these amines.
I
S 4 continuation of the work on qualitative tests for the
functional groups present in surface-active agents ( d ) , it has been found that p-hydroxyethylamines may be detected by a modification of the Hofmann degradation of quaternary ammonium hydroxides ( I ) . The @-hydroxyethylamine group is present in several classes of surfactants, such as diethanolamine-fatty acid condensates of the Kino1 type, p-hydroxyethylimidazolinea, and various hydroxyethylated long-chain amines. In addition, such p-hydroxyethylamines as triethanolamine, diethanolamine, and diethylaminoethanol are commonly used to form salts of fatty acids and other acidic compounds which are important emulsifying agents.
N. Y. The test depends upon the thermal decomposition of a quaternized 6-hydroxyethylamine to yield acetaldehyde, according to the following equation:
[R3~C11,CHzOH] +CHaCHO
+ [RJHI
+
The formation of acetaldehyde is detected by leading the volatile material produced during the pyrolysis into a solution of sodium nitroprusside containing a water-soluble secondary amine. If acetaldehyde is present, it reacts to form a blue color. This latter reaction is a reversal of the Simon test (3) in which water-soluble secondary amines are detected by the blue color (of unknown structure) which they produce with a solution of sodium nitroprusside containing acetaldehyde. I n order to ensure a uniform temperature for the thermal decomposition, an inert, high-boiling solvent was added to the reaction mixture, and constant temperature was maintained by conducting the reaction a t its boiling point. After a number of trials using various solvents, the dimethyl ether of tetraethylene
115
V O L U M E 2 7 , NO. 1, J A N U A R Y 1 9 5 5
test. Moreover, the use of sodium chloroacetate makes it unnecessary to convert the quaternary ammonium compound formed to its corresponding hydroxide in order for decomposition to occur. The action of sodium chloroacetate on a tertiary aniiiie produces a betaine, RzN( CH~CH~OH)CHZCOO-, which under the conditions of the test, decomposes directly to acetaldehyde.
glycol was selected as having physical and chemical characteristics most suitable for the purpose. Sodium chloroacetate was found to be a more effective reagent than methyl iodide for quaterniing these amines, since its use yielded acetaldehyde with both secondary and tertiary P-hydroxyethylamines, whereas methyl iodide, under the same conditions, yielded acetaldehyde only from tertiary P-hydroxyethylamines. Ethanolamine, the only primary p-hydroxyethylamine, does not yield acetaldehyde when treated with either methyl iodide or sodium chloroacetate, and therefore does not respond to this
Table 1.
+
RZNCHZCH~OH CICHzCOONa --f
+
R ~ ~ ( C H ~ C H ~ O H ) ~ : H ~ CxaC1 OO-
Reactions of Various Amines and Nitrogen-Containing Surface-Active Agents to Pyrolj-sis with Sodium Chloroacetate Color
Product Diethanolaniine Diethanolamine HC1 Triethanolamine Triethanolamine pliosphate Duponol WATb Diethylaminoethanol N-Ethyldiethanolaniine N-Hydroxyethylpropylenedi-
amine N , N’-Dihydroxyethylethylenediamine
Source Carbide & Carbon Carbide & Carbon Beacon Du Pont Eastman Kodak Eastman Kodak Carbide & Carbon
Bfter 5-min. pyrolysis Light blue Royal blue Royal blue Royal blue Royal blue Royal blue Royal blue Royal blue
Structure (HOCHzCHz)z.VH (HOCHzCHn)zP;Hz+Cl(H0CHzCHx)rN [ HOCHzCHz)~PiH+]aPO~-~H0CHzCHa)sNHJ +OSOzORC OCHtCHzK(CH2CHa)z (H0CHzCHz)zKCHzCHs HOCHzCHzNHCH(CHs)CHzKHz
ii
IO-min. standing “CuSO1” blue Deep blue Deep blue Deep blue Deep blue Deep blue Deep blue Deep blue T
+++ + +
Carbide & Carbon
HOCZHIXHCZHPNHCZHIOH
Royal blue
Deep blue
Carbide & Carbon
HOCHZCHZNCZHIOCZHI
Royal blue
Deep blue
N - a-?lethylbenzyldi~thanolamine Amine 220
Carbide & Carbon
(HOCHzCHz)~NCH(CHa)CsHs
Royal blue
Deep blue
Carbide & Carbon
HOCHZCHZKCZHIN=C-RC
Royal blue
Deep blue
Amine 0
Alrose
HOCHz C Hz NCz Hd=C-Re
Royal blue
Deep blue
Versen-ol b Priminox 43 Priminox 10 Priminox 21 Priminox 32
Bersworth Rohm & Haas Rohm & Haas Rohm & Haas Rohm & Haas
(SaOOCCHz)zNCzH4N(CHzCOONa)CzH~OH
Royal blue Royal blue Light blue Light blue Light blue
Deep blue Deep blue “CUSOI” blue “CuSO4” bIue “CuSO4” blue
++ ++ +
Ethomeen T/15
.4rmour
Royal blue
Deep blue
+
Ethoineen S / 2 0
.4rmoui
L-i
L J -
L-i
HOCHzCHzPiH-RC H(0CHzCHz)zNH-RC II(OCHzCHz)zNH-Rc H(OCHzCHz)zKH-RC H(OCHICHZ)Z >---Re H (OCHzCHz) y H (OCHz CHz)z ) % K C
H(0CHzCHz)g H (OCHzC Hn) z >N--K“ H(0CHzCHz) y H(0CHzCHz)z
(Z =
(Z = (Z =
5) 15) 25)
+ + +
(z
+y
= 5)
(z
+u
=
IO)
Royal blue
Deet, blue
+
(2
+9
=
15)
Light blue
Royal blue
+
Ethonieen C/25
-4rmour
Ethomeen 18/60
Armour
Light blue
“CuSOJ’ blue
+
Eastman Kodak Alrose
Light blue Royal blue
“CuSO4” blue Deep blue
++
Royal blue
Deep blue
Royal blue
Deep blue
Royal blue
Deep blue
Royal blue
Deep blue
t
Royal blue
Deep blue
+
Deep blue Pale yellow Pale yellow Gray-brown
[HOCH(CHa)CHzlaPi (C4Hs)aN (C4Hs)ahHTC1(CsHsCHi)sN HzNCzHaNHCzH$VHz HOCHzC(CHa)zh Hz
Royal blue Pale yellow Pale yellow Pale b l u e purple Pale purple Pale yellow Pale yellow Colorless Pale yellow Pale yellow
(HOCHz)zC(CHdKHz
Pale yellow
Pale yellow
(H0CHz)sCNHz
Pale yellow
Pale yellow
CHaXHCHz(CHOH)4CHzOH
Pale purple
Purplish gray
Purplegray
Pale bluegray
-
Purplegray
Pale bluegray
-
Ninol %-in01 2012.4
h-inol
Ninol .4.462
Xinol
Sinol 201
Ninol
Alrosol 0
-4lrose
Drisyn R I onoethanolannne Isopropanolamine Diisopropanolamine
Drew Carbide & Carbon Carbide & Carbon Carbide & Carbon Carbide & Carbon Eastman Kodak
2-.4mino-2-methyl-l,3propanediol Tris(hydroxymethy1)aminomethane S - M e t hylglucaniine
C
++ +++
N-Hydroxyethylmorpholine
~~
a b
Result
Solvents Commercial Solvents Commercial Solvents
Ethomid C / l 5
.4rinour
Ethomid R 0 / 2 5
.4rmour
(1 : 1 molar ratio) Diethanolamine-Coc. F.A. condensate (2: 1 molar ratio) Diethanolamine-lauric acid (2: 1 molar ratio) Diethanolamine-oleic acid (2 : 1 molar ratio) Diethanolamine-oleic acid (2 : 1 molar ratio) Diethanolamine-fatty acid condensate HOCHzCHzh-Hz H 0C H (C Ha) C Hz XH; [HOCH(CHs)CHz]zh H
H(0CzHc)z
8
(z
+y
A
(Z
+ u = 15)
)NCRC H(0CzHa)y H(OCZHI)Z >NCRC H(OCsH4)y
= 5)
+
+
+ +-
Prepared by adding dilute hydrochloric acid t o the amine until acid t o methyl orange, then evaporating the resulting solution t o constant weight Dried a t 115O C. R = alkyl or alkenyl group of 12 t o 24 carbon atoms.
-
116
ANALYTICAL CHEMISTRY
RJ( C H ~ C H ~ O H ) C H ~ C OT+ OR&HCH~COO-
+ CH~CHO
Tlie water-soluble secondary amine chosen for use with sodium nitroprusside, in detecting the formation of acetaldehyde, was diethanolamine, since its stability, water-solubility, and low volatility made it appear eminently suitable for the purpose. Table I lists the reactions to this test of various amines and nitrogen-containing surface-active agents. PROCEDURE
Two hundred milligrams (or 4 drops) of a riitrogeii-coritairiirlg compound, 0.2 to 0.3 gram of sodium chloroacetate (Dow Chemical Co., technical grade, was used), and 1 to 1.5 ml. of tetraethyleneglycol dimethyl ether (Ansul Chemical Co. ) are placed in a 5-inch test tube and agitated vigorously for a few seconds. The test tube is clamped a t an angle of no more than 30’ from the horizontal (to eliminate spatt’eringduring the pyrolysis) and a glass delivery tube with a GOO-angle bend is att,ached by means of a one-hole rubber stopper. The end of the delivery tube passes beneath the surface of the “detecting solution” contained in a +inch test tube support’edby a wire gauze placed across an iron ring. I n order to facilitate observation of color changes in the detecting solution, a piece of whit’e paper is placed over thr wire gauze supporting the test tube containing the solution. The detecting solution consists of 1 ml. of water to which havr been added 2 drops of sodium nitroprusside solution (20 grams of‘ Xa2Fe(CN)&O.2H20 dissolved in 50 ml. of water and diluted with 450 ml. of methanol) and 1 drop of diethanolamine. The contents of the 5-inch test tube are now heated with a m a l l flame a t such a rate that bubbles of gas pass through the detecting solution a t a rate not exceeding one per second. The contents should boil vigorously and the solvent should reflux from the upper portion of the test tube, but distillation of any appreciable amount of solvent must be avoided. The heating should be continued for no longer than 5 minutes. The appearance of a definite blue color in the detecting solution during the pyrolysis period constitutes a positive result. As indicated by Table I, most P-hydroxyethylamines give a royal blue color (usually after heating the quaternized amine for about 3 minutes). In those cases where a light blue color is obtained, the detecting solution should be allowed to stand for up to 10 minutes and then re-examined. If the blue color has deepened to a brilliant royal or “copper sulfate” blue, the test is considered positive. If the light blue color persists or fades, the tePt is (sonsidered negative, since traces of blue may he d u e to
P-hydroxyethylaniine impurities present in commercial materials of related structure. DISCUSSION OF RESULTS
All P-hydroxyethylamines tested give positive results with this test. In addition, amines containing one or tm-o polyethoxyethm o l groups attached to the amino nitrogen give positive results, alt~hough,. as the size of the polyethoxyethanol group increases, with consequent decrease in the nitrogen content of the molecule, the results become less definite (Priminox 43 us. 32; Ethomeen T/15 us. 18/60!. I n di(8-hydroxyethyl)aniline, the presence of the aromatic nucleus, with its electron-attracting capacit,y, apparently inhibits the decomposition to acetaldehyde, and only a light blue color (which deepens on standing, however) is obtained. This tendency is intensified in t,he amides where the strongly electron-attracting C=O group inhibits the reaction to such an extent that ethoxylated amides give negative results (Ethomids C/15 and R0/25). lsopropanolamines (mono-, di-, and tri-) all give negative results, since they cannot decompose to acetaldehyde. This makes the test valuable in distinguishing between emulsifying soaps made with triethanolamine or diethanolamine and those made with di- or triisopropanolamine. The positive results obtained wit,h diethanolamine hydrochloride, and triethanolamine phosphate indicate that in analyzing amine-containing compositions it should not be necessary to isolate the amine per se, but that a salt of the amine, often more conveniently obtained, may be tested instead. The triethanolamine salt of an anionic surfactant (Duponol W.4T) can be deiected with this method. ACKNOWLEDGMENT
The author \vishes to acknowledge gratefully the valuable suggest,ions made by David Davidson of this department during thr course of this investigation. LITERATURE CITED
(1) Hofinann, A4. W., Ber., 14, 494, 659, 710 (1881). (2) Rosen, AI. J., ANAL. CHEM.,26, 1 1 1 (1954). (3) Simon, L. J., Compt. rend., 125, 536 (1897). KFEEIYEDfor review May 7, 1954.
Accepted July 16, 1954
Colorimetric Determination of Niobium in the Presence of Tantalum MOHAMMED NAB1 BUKHSH’ and DAVID N. HUME Department
of Chemistry
a n d Laboratory of Nuclear Science, Massachusetts institute of Technology, C a m b r i d g e 39, Mass.
The major sources of error in the thiocyanate method for the colorimetric determination of niobium are loss of niobium due to hydrolysis of tantalum present and incomplete extraction of the niobium thiocyanate complex with ether. These effects have been minimized by adding tartaric acid to the reagents, changing the order of additions, and replenishing the thiocyanate and acid between extractions.
T
HE greatest drawback to the colorimetric determination of
niobium with thiocyanate has probably been the interfering effect of tantalum a t high ratios of tantalum to niobium. The authors have observed, in using a recently published procedure (a), that although satisfactory results are obtained a t a 10 to 1 ratio of tantalum to niobium a t low levels of niobium concentration, poor results are obtained a t the same ratio with larger con1 Present address, Central Testing and Standards Laboratories, Karachi, Pakistan.
centrations. They therefore extended their studies on the thiocyanate method with particular attention to the tantalum interference problem. The two main sources of error have been found to be: incomplete extraction of the niobium from the aqueous phase, and loss of niobium due to hydrolysis of tantalum present, the latter effect being the more important. It has been shown that addition of tartaric acid to the reagents and a change in the order of addition eliminate the erratic interferences of tantalum. EXPERIMENTAL
A majority of the reagents were prepared as in previous work ( 4 ) . Niobium and tantalum stock solutions were made up from spectrographically analyzed high purity oxide as before. The oxides were fused in silica crucibles with potassium pyrosulfate, with special care to obtain clear melts, and the cooled masses were taken up in 10% tartaric acid. Close attention to detail was found necessary in high tantalum mixtures if clear solutions were to result. The pure niobium stock solutions were found to be stable, but tantalum stock solutions showed a tendency to hvdrolyze on standing. The spectrographically pure ouidr
