A NEW ADDITION APPARATUS IRVING SCHEER and AMEDEO P. D'ADAMO, b. Ortho Research Foundation, Raritan, New Jersey
ADDITION of a solid reagent in small portions to a reaction mixture, particularly reagents which are sensitive to air and moisture such as lithium aluminum hydride and sodium hydride, is usually an awkward and troublesome procedure. Fieserl describes an apparatus for such addition which consists of an Erlenmeyer flask fitted to one of the tubnlatnres of the reaction vessel by a section of rubber tubing. The intermittent addition of the solid is accomplished by raising the containing flask which can then be cut off from the system by kinking the rubber tube. However, several disadvantages are inherent in this method: the rate of addition of the solid is difficult to control and condensing solvent vapors may clump up the reagent so that complete addition is prevented. Solids may also be added from a hopper provided with a glass valve as described by Webster and Dennis.= This apparatus is somewhat difficult to manipulate and does not prevent the solvent vapors from coming in contact with the reagent. We have devised an addition apparatus which does not suffer from these disadvantages. As shown in the figure, it consists of two parts, A and B. The essential features of the avvaratus are a half-moon plate sealed FIESER,L. F., "Experiments in Organic Chemistry," D. C. Heath $ Co., 2nd ed., New Yark, 1941, p. 311. WEBSTER, 8. H., AND L. M. DENNIS, J. Am. Chem. Sac., 55, 3234 (1933).
into part B and the construction of part A in such a fashion that when it is fitted into part B, the open bottom fits snugly on the glass plate when in the closed position. In operation, the solid is charged into part A and moisture and air excluded by sealing with a ground-glass stopper. The rate of addition is controlled by rotating part A. I n reactions where reflnx is necessary, a straight condenser may be interposed between the reaction vessel and the addition apparatus, thus preventing the wetting of the reagent with solvent. We wish to thank the Kontes Glass Company for construction of the original model.
~ l a r sp l a t e sealed in; -upper face ground
Ground to fit plate
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VOLUME 35, NO. 6, JUNE, 1958
PART B
PART A
