got
40-
30-
2010-
4
3
5
6 Figure 1.
Table 1.
Analysis of Chlorendic-Type Alkyd Chlorendk Acid
Found (Gravimetric)
%
Found (new method), %
34.2 45.2
47.0, 4 7 . 3
Present, f+rnple 81% g. 3’% 47.2O
4
1 2 3 4
48.1 50.8
Obtained from total chlorine analysis.
The chlorendic acid is extracted with 7 5 , 50-, and 50-ml. consecutive volumes of ethyl ether, with vigorous shaking in each extraction. The ether extractions are collected and washed with 25ml. portions of water until acid-free. If phthalic acid is present, as many aa eight washings with 50-ml. portions of water may be necessary. The ether is withdrawn into a 500-ml. Erlenmeyer flask and 75 ml. of absolute ethyl alcohol are added. Five milliliters of m-cresol purple indicator (0.025 gram in 100 ml. of absolute ethyl alcohol) are added and the sample is titrated to a purple end point with 0.2N potassium hydroxide in absolute methanol.
yo chlorendic acid
=
ml. of alkali X normality X 19.45
sample weight
x nonvolatile vehicle fraction
DISCUSSION
The presence of potassium carbonate in the alcoholic alkali causes no interference and need not be removed. As
7
8
9
IO
II
12
13
14
MICRONS hfrored spectrum of chlwendic acid alkyd
the precipitated salts are not weighed, the filtration crucibles do not require drying or weighing, but if freshly prepared with filter asbestos, they should be rinsed with alcohol and benzene before using. If phthalate esters are known to be present along with the ehlorendic alkyd, a more thorough washing of the ether extracts will be necessary to remove phthalic acid, which is soluble in both ether and water. This separation is made possible by the near insolubility of chlorendic acid in water and its high solubility in ether. An infrared spectrum of the resin sample is useful, particularly if the material is of unknown origin, to detect other dicarboxylic acids and to establish the presence of chlorendic acid. The chlorendic acid alkyds do not show the strong, characteristic phthalate ester absorption bands at 7.8, 8.8, and 9.3 microns that are always exhibited by infrared spectra of phthalic alkyds. The medium to strong aromatic substitution bands in the 13.5- to 14.5 micron region are also missing. They are characterized by a strong band a t 8.45 microns arising from the aliphatic ester structure and a band of medium strength at 12.2 microns due to the - C C l r grouping as illustrated in Figure 1. This spectrum was obtained with a Perkin-Elmer Model 21 spectrophotometer. The resin film was dried on a sodium chloride plate in a vacuum oven a t 60’ C. for 1 hour. The limited analytical data are due to the scarcity of commercially available materials a t the present time. Although sources are limited, the chlorendic acid
alkyds have already attained considerable commercial importance. The authors feel confident that the analytical method will be applicable to other alkyds based on this dicarboxylic acid, as they become available. ACKNOWLEDGMENT
The advisory assistance of C. F. Pickett, director of the laboratory, is acknowledged and appreciated. LITERATURE CITED
(1) Am. Soc Testing Materials, Phil-
adelphia, “ASTM Standards,” Designation D 563-52, 597 (1958). (2) Zbid., D 1306-54T, 599. (3) Ibid., D 1307-54T, 602. (4) Esposito, G. G., Swann, M. H., ANAL.CHEM.32,49 (1960). RECEIVED for review September 29, 1959 Accepted February 9, 1960.
Correction Rapid Method for Semiquantitative Determination of Volatile Aldehydes, Ketones, and Acids I n this article by Jack W. Ralls [ANAL.CHEM.32, 332 (1960)], on page 336, the first line after the Literature Cited section should read Received for review, April 20, 1959.
VOL 32. NO. 6, M A Y 1960
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