Dimroth reflux condenser

Dimroth reflux condenser, 59, 20 Dimsyl anion, 55, 18 Dineopentyl sulfides, 58,146 Dinitrogen tetroxide, 56, 65... 

The apparatus used for preparation of Grignard solutions is usually a twonecked flask carrying a reflux condenser (wide bulb condenser or Dimroth condenser) and a dropping funnel, but there are advantages in using a threenecked flask as a stirrer can then be incorporated. 

New Jersey 08360. A Dimroth condenser is recommended for use with refluxing liquids that boil up to 160°. Since the points of sealing are situated above the zone with a high temoerature gradient, the risk of cracking from thermal stress is minimized. The a-chlorination of aliphatic acids by this procedure is usually carried out at 110-140° (see Table I). The submitters circulated ice-cold water through the condenser. 

In order to concentrate a solution the solvent is distilled through a downward condenser . For this purpose various forms of coil condenser are more convenient than the Liebig pattern. For working under reflux such coil condensers are less suitable because of the layers of liquid which form in the coil between the vapour and the external atmosphere. A condenser designed by Dimroth has proved suitable for both types of work. In it the cooling water passes through the coil (Fig. 1). In order to prevent condensation of water vapour on the coil it is advisable to fix a calcium chloride tube into the upper opening of the condenser. 

The venerable Dimroth triazole synthesis is a base-catalyzed condensation of an azide 1 with an active methylene compound 2 to provide a 1,2,3-triazole derivative 3. Commonly, this reaction is run with an alkoxide base in the corresponding alcohol solvent at ambient temperature or reflux/ "" ... 

C-Nucleosides have also been prepared via Dimroth rearrangement. These compounds are desirable targets for the treatment of bacterial and viral infections due to their metabolic stability toward phosphorylase enzymes. Condensation of C-nucleoside 15 and 2-hydrazinopyrimidine 16 in refluxing ethanol led to the production of a nonisolatable purine analog intermediate, which underwent spontaneous Dimroth rearrangement to yield 17. This compound was isolated after treatment with methanolic ammonia to give the desired product in 45% yield. 

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