m-Cresoxyacetic Acid as a Reagent for Thorium

Abstract

rpHH separation of thorium from the rare earths, particularly in -* monazite, is of great interest. Previous work on the subject has been critically reviewed by XX'illard and Gordon (11), who also describe an elegant method for the decomposition of monazite and the estimation of thorium therein. Reference may also be made to a later communication by Gordon, Vanselow, and Willard (£). Several reagents have been under investigation in this laboratory (4, 9, 10). Organic reagents present the advantage that the precipitate is voluminous and enable small quantities of the metal ion to be handled convenient!!". m-Cresoxyacetic acid, which is described here, gives with as little as 2.0 mg. of thorium oxide a precipitate large enough for easy handling. The precipitate has a varying composition and cannot be weighed directly, but this difficulty is overcome by igniting to the oxide.

Thermolysis of Thorium Precipitates Salts of Organic Acids

“…Preparation of Precipitates. The thorium precipitates were prepared according to procedures described (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12). In general, an aqueous solution of the organic acid was added to a boiling hot solution containing about 0.2 gram of thorium nitrate in 150 ml.…”

“…and minimum oxide temperatures. The precipitates examined have all been prepared previously: the thorium salts of stearic, pyrogallic, m-hydroxybenzoic (8), m-cresoxyacetic (8), benzoic (9,12), 2,4-dichlorophenoxyacetic (2), phenylacetic (1, 6), cinnamic (4,10,11), and o-aminobenzoic (anthranilic acid) (5) acids, and mercaptobenzothiazole (7).…”

Inorganic Gravimetric Analysis

“…Other new aliphatic reagents recorded were adipic and succinic acids (287), the latter having lesser value for separations from rare earth elements. New aromatic reagents recorded were vanillic acid (150); m-cresoxyacetic acid (323); ammonium picrate and ammonium 2,4-dinitrophenol (235); camphoric acid (197); ammonium furcate and sodium sulfanilate (161); pyrogallic and m-hydroxybenzoic acids (58).…”

Spectrophotometric Determination of Thorium in Monazite Sands

“…Some of these are new, and others are modifications and improvements of older procedures. The use of organic acids to precipitate thorium selectively has received wide attention (6, 10, 13- [45][46][47][48][49]51). Other precipitation methods investigated recently use selenious acid (2), iodic acid (45), potassium iodate (51), ammonia (3) at a controlled pH, and radioactive pyrophosphate (26) in which the activity of the excess pyrophosphate in the filtrate is measured.…”