ANALYTICAL CHEMISTRY
435 Table 7’111. Purity of Anhydrides by Morpholine-Carbon Disulfide nIethod Total, 70b y Wt. - Purity, b y Wt.a Anhydride
Morpholine carbon hlorphodisulfide lineD 98.8 0.1 (4) 9 8 . 9 97.3 f 0.2 (2) 96.9 97.4 0.2 (2) 97.8 (Carbic) 96.0 5 0 . 0 (2) 0.2 (2) oi:i 90.9 98.2 i: 0.1 (4) 98.5 f 0.05 (2) 9~:s 99.5 i 0.2 (2) 99.4 96.5 =t 0.1 (2) 96.9 95.7 i 0.1 (2) 95.2
*
*
*
Propjopic Succinic a
Scid Content,
% by Wt.“ 0 . L i: 0.1 (4)
* *
2 . 7 f 0.1 (2) 1.83 0.0 (2) 1 3 i 0.0 (2) 8.i) 0 . 0 (2) O.!) 5 0.03 4) =t 0 . 0 5 12) 0 0 f 0.05 (2) 3.3 zk 0.0 (2) 4 . 1 :k 0.05 (2)
hl orpholine-
fiIorpho-
disulfide 99.2 100.0 , 99.0 97.5 99.8 99.1 100.0 ion.1 99.8 100.1
linea 99.3 99.6 99.4
100:o
i0i:o
100.0 100.2 99.6
Figures in parentheses indicate number of determinations. of Johnson and F u n k (6).
b Procedure
Table IX. Analysis of Mixtures of Anhydrides and Their Corresponding Acids by Morpholine-Carbon Disulfide illethod dcid-4 n h yd ride Mixture
Maleic Acetic
Added, % b y Wt. AnTotal Bcid hydride 74.0 99.4 26.4 46.0 99.6 53.6 45,5 99.3 53.8 99.3 77.6 21.7
LITERATURE CITED
Found, % b y Wt. Anhydride Acid Total 25.7 74.3 100.0 53.7 46.0 99.7 53.9 45.4 99.3 21.9 77.7 99 6
with results obtained using the method of Johnson and Punk (6). The precision is in the order of &O.l% for the determination of purity. I n Table IX the analyses of several known mixtures of carboxylic acids and their corresponding anhydrides are listed. For these data the accuracy of the method is within =k0.2% for both the acid and the anhydride determinations. I n general, the method is subject to the same interferences as the method of Johnson and Funk ( 6 ) , except that organic acids interfere quantitatively and tertiary amines are not basic to the indicator. The method is applicable to the determination of a wide variety of anhydrides. Maleic anhydride can be determined by the method if O.2N morpholine solution is used. TT‘ith l.0.V morpholine, addition across the double bond occurs. The method of Johnson and Funk (6) cannot be used for this
anhydride because maleic acid is acidic to the indicator used in this method. Of the comp o u n d s i n v e s t i g a t e d only acrylic and chloroacetic anhydride could not be determined b y t h i s m e t h o d . Halogensubstituted anhydrides react with morpholine to liberate a h a l o g e n acid; acrylic compounds add morpholine acrom the unsaturation. The method also has merit in that both the acid and anhydride determinations are obtained using a single sample and titrant.
Carpenter, A. L., Coldfield, S., Wilson, D. L., U. S. Patent 2,566,717 (Sept. 4, 1951). . 28,436 (1956). Critchfield, F. E., Johnson, J. B., A N ~ LCHEM., Hawkins, TV., Smith, D. AI., Mitchell, J., Jr., J . Am. Chem. Soc. 66, 1662 (1944).
Hofman, A. TV., Ber. 1 , 169 (ZSSS). Johnson, J. B., Funk, G. L., unpublished data. Johnson, J. B., Funk, G. L., ANAL.CHEM.27, 1464 (1955). NcIntire, F. C., Clements, L. RZ., Sproull, AI., Ibid., 25, 1757 (1953).
AIi’tcheli, J., Jr., Hawkins, IT’., Smith, D. hl., J . Am. Chem. SOC. 66, 782 (1947).
Rlizuch, I
