Reaction methods liquid reagents

Tritylpotassium. (CeHslaCK (deep red). In one method the reagent is prepared by reaction of triphenylmethane with potassium in liquid ammonia and replacement of the ammonia by ether to give a suspension of the reagent and provide a medium suitable for acylations, alkylations, and carbonations. Tritylsodium also can be prepared from triphenylmethane in the same way, but it is destroyed when the ammonia is replaced by ether the preparation of an ethereal solution from trityl chloride and sodium takes considerably longer than the preparation of tritylpotassium from triphenylmethane. Moreover, triphenylmethane is recoverable in good yield from a condensation in a form suitable for reuse. Typical reactions utilizing tritylpotassium are an ester condensation (1 ), an acylation (2 ), an alkylation (3 ), and a carbonylation (4 ). 

The liquid reagent has high solvent power, particularly for oxygen-containing substances and for aromatic compounds. It is an effective dehydrating and condensing agent comparable to coned, sulfuric acid but less prone to permit secondary reactions such as enolization and aromatic substitution. Treatment with liquid HF at room temperature provides a simple and efficient method for the cyclization of /3-arylpropionic acids and y-arylbutyric acids to 1-indanones and 1-tetralones, as shown by the yields cited under the formulas of typical ketones. It is far superior... 

Liquid reagents and solutions are added to a reaction by several means, some of which are shown in Figure 7.9. For microscale experiments, the simplest approach is simply to add the liquid to the reaction by means of a Pasteur pipette. This method is shown in Figure 7.9A. In this technique, the system is open to the atmosphere. A second microscale method, shown in Figure 7.9B, is suitable for experiments in... 

Phenylcyclopropane has been prepared by the base catalyzed decomposition of 5-phenylpyrazoline (33 %),2 by the reaction of 1,3-dibromo-l phenylpropane with magnesium (68%),3 and by the reaction of 3-phenylpropyltrimethylammomum iodide with sodium amide in liquid ammonia (80%)4 However, the method frequently used at present is the reaction of styrene with the methylene iodide-zinc reagent (32%)5... 

Thiophenes of type 31 (X-Y = CH) were generated via Lawesson s reagent-mediated cyclization of 1,4-dicarbonyl compounds 30 under microwave irradiation in the absence of solvent [37]. The reaction was carried by mixing the two solid reagents in a glass tube inserted inside a household microwave apparatus and irradiating until the evolution of H2S ceased. An interesting application of this method is the preparation of liquid crystals and other ferro- and antiferroelectric material such as compound 33 (Scheme 10). 

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