As dehydrating reagent

The conversion of cyclic a-halo ketones into amino-substituted allyl halides 8 can be facilitated by the use of titanium(IV) chloride as dehydrating reagent." The ring closure into cyclic iminium... 

Useful application of Tf20 as dehydrating reagent is accounted by the synthesis of isocyanides from formamides and vinylfor-mamides (eq 43). ... 

Trifluoroacetic anhydride, thionyl chloride,and carbonyl chloride have been applied as dehydrating reagents. When trifluoroacetic anhydride is used, a reaction that usually takes a few days can be completed in seconds. In aqueous solution, N,N-diisopropylcarbodiimide has been used in this reaction at room temperature. 

Thermally-sensitive hydrogels were also used as dehydration reagents. In this case, the water absorption and desorption is led in the proximity of phase-transition temperature of used gels. Polymer gels based on N-isopropylacrylamide have been used for concentrating albumin, gelatine or dextrane solutions [135]. 

In a facile synthesis of 6-hydroxyindole-3-acetic acid, the o-isocyanodimamate route was also chosen [1183], as in a similar synthesis carried out with phosgene [1168 see above]. The isocyanide was obtained in 92% yield by using triphosgene as dehydration reagent [1183]. 

Cyanopyridine 23 has been prepared from nicotinic amide by several methods, in good to excellent yidd in each case. As dehydration reagents, phenyl chloroformate [28], phenyl chlorothionoformate [29], oxalyl chloride/DMSO [30], triflic anhydride [31], and the Burgess reagent [32] have been used, giving yields of 23 of 92%, 92%, 75%, 93%, and 92%, respectively. 

Potassium Oxalate. The monohydrate [6487-48-5] K2C204-H20, mol wt 184.24, is produced as a colodess crystalline material or a white powder. The anhydrous salt [583-52-8] mol wt 166.22, is obtained when the monohydrate is dehydrated at 160°C. The monohydrate is preferred as a reagent in analytical chemistry and in miscellaneous uses principally because of its high solubihty as compared with other simple neutral oxalates the saturated solution, at 0°C, contains about 20 wt %, and at 20°C, about 25 wt %... 

Dehydration of fi-nitro iilcohols provides an important method for the preparation of nitroalkenes. Because lower nitroalkenes such as nitroethylene, Tnitro-Tpropene, and 3-nitro- Tpropene tend to polymerize, they must be prepared careftdly and used immediately after preparation. Dehydration v/ith phthalic anhydride is the most reliable method for such lower nitroiilkenes. Such lower nitroalkenes have been used as important reagents for Michael acceptors or dienophiles in the Diels-Alder reacdon, which v/ill be... 

---