THE TWO PHTHALOXIMES : A STUDY OF THEIR ABSORPTION 

 SPECTRA AND CONSTITUTION 



By D. S. Pratt and H. D. Gibbs 1 



(From the Laboratory of Organic Chemistry, Bureau of Science, 

 Manila, P. I.) 



Two plates and 6 text figures 



Phthaloxime was first described by Lassar-Cohn, 2 who made 

 it by the action of phthalyl chloride on hydroxylamine. The 

 same compound was later made by Lach, 3 who employed phthalic 

 anhydride and hydroxylamine. Orndorff and Pratt 4 have shown 

 that the course of this reaction depends upon the temperature. 



A colorless phthaloxime is formed at 60°, and a lemon yellow 

 isomer results when the same reaction takes place at 100°. 

 These two isomers are very closely related, as shown by their 

 physical characteristics and chemical properties. The principal 

 difference between them is their color. Two structures are 

 theoretically possible for phthaloxime, depending upon whether 

 the hydroxylamine residue is in the symmetrical (1), or unsym- 

 metrical (2), position in respect to the benzene ring. 



x 



NOH 



i~ C \ 



^0 \/ ^NOH 



The symmetrical formula (1) has been generally assigned to 

 colorless oximes of this type regardless of the color of their salts. 

 Both the white and the yellow phthaloxime give alkali salts of 

 a brilliant red and of almost identical color in both cases. It 

 has not been found possible, as yet, to prove beyond question 

 which of the above formulas should be applied to phthaloxime, 

 although a careful study of its formation and reactions points 



1 Associate professor of chemistry, University of the Philippines. 

 3 Ann. d. Chem. (Liebig) (1880), 205, 295. 



3 Ber. d. deutschen chem. Ges. (1893), 16, 1781. 



4 Am. Chem. Journ. (1912), 47, 89. 



165 



