A Simple and Inexpensive Dilution Apparatus The synthesis of medium- and larger-ring compounds using the dilution principle has, previously, seldom been included in the chemistry students' practical program. Thismay be mainly based on the fact that the terns "medium rings" and "dilution principle" have frequently been equated with elaborate and costly equipment and with practical expertise. Since glassware and apparatus presently available for such proeeduresl is indeed rather expensive, we have designed a simple and inexpensive setup which has proved quite useful and perfectly satisfactory far many dilution reactions. The apparatus,a which in arrangement (a) (see drawings) may be connected to a single-neck flask, resembles a normal three-socket adaptor. It differs from the normal adaptor, however, in that it is fitted with a 10-mm-high collar, which serves as a reservoir for approximately 25 ml of liquid. The central socket and ground-glass joint is used far insertion of the stirrer, and the two side necks for attachment of a dropping funnel and reflux -condenser, respectively. The reactant added dropwise from the dropping funnel can thus be pre-diluted with refluxing solvent in the reservoir hefore entering the reaction flask. The diluted solution overflows from the reservoir collar into the middle of the wellstirred contents of the flask. If two different reactants are to he added simultaneously then two of the simpler dilution adaptors shorn in drawing (b) are used; they are connected to the two side necks of a three-neeked flask. The middle neck of the threenecked flask is used for canying the stirrer; it is advantageous in longtime experiments to use stirring bushes made from polytetrduoroethylene. In this arrangement care should also he taken to ensure that both reflua condensers deliver ~pp&imately the same amount of condensate. a review see Vegtle, F., Chemiker-Ztg., 96,396 (1972) Vbgtle, F., and Wittig, G., Pat. pend..
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Institut fim Organische Chemie der Universitat 87 Wwzhurg, Landwehr, Germany
650
/ Journal of Chemical Education
Fritz Vagtle Girnther Wittig
