Stedman

The Stedman-type column is shown in Fig. 11, 56, 25. The characteristic features are (i) the use of a fine stainless steel wire cloth formed into conical discs, and (ii) an accurately fitting Pyrex glass jacket, produced by shrinking Pyrex glass on mandrels to the required inside dimensions. Modifications incorporating a silvered vacuum jacket and an electrically-heated jacket are marketed. This column is said to possess high efficiency but is expensive. It is generally employed in conjunction with a total-condensation variable take-off still head. 

Fig. 10. The postulated interaction of a-adrenoceptor agonists with the receptor. The Easson-Stedman hypothesis suggests that (R)-noradrenaline is most potent owing to its three points of attachment () to the adrenoceptor, whereas dopamine and (5)-noradrenaline are equal in activity, but less active...

Methyl trichlorosilane [75-79-6] M 149.5, b 13,7 /101mm, 64.3 /710.8mm, 65.5 /745mm, 66.1 /atm, d 1.263, n 1.4110. If very pure distil before use. Purity checked by Si nmr, 6 in MeCN is 13.14 with respect to Me4Si. Possible contaminants are other silanes which can be removed by fractional distillation through a Stedman column of >72 theoretical plates with total reflux and 0.35% take-off (see p. 441). The apparatus is under N2 at a rate of 12 bubbles/min fed into the line using an Hg manometer to control the pressure. Sensitive to H2O. [J Am Chem Soc 73 4252 7957 J Org Chem 48 3667 7955.]... 

The miotic effect induced by physostigmine lends itself to investigation of the interrelation of chemical constitution and pharmacological action, and Stedman has devoted much attention to this subject. Eseroline is devoid of miotic activity, so that the latter action in physostigmine must be mainly due to the fact that it is a methylurethane, and, since activity only becomes evident in the urethanes of phenolic bases or phenols with a basic side-chain, a basic nucleus for the urethanes appears also to be essential. 

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