Caffeine 5-Nitrosalicylate

One such add is 5-nitrosalicylic acid, which is prepared by nitration of salicylic acid in Experiment [29]. The purified caffeine obtained in this experiment may be further characterized by preparation of the 5-nitrosalicylate complex. This association is similar to the natural one formed with 3-caffe oylquinic acid  

Reagents and Equipment. Weigh and add to a 3.0-mL conical vial, containing a magnetic spin vane and equipped with an air condenser, 11 mg (0.06 mmol) of caffeine, 10.0 mg (0.06 mmol) of 5-nitrosalicylic add, and 0.7 mL of ethyl acetate. 

Reaction Conditions. Gently warm the mixture on a hot plate, with stirring, to dissolve the solids. Add 0.5 mL of petroleum ether (bp 60-80 °Q to the warm ethyl acetate solution, mix, and warm for several seconds. Remove the spin vane using forceps. 

Isolation of Product. Cool the mixture to room temperature and then place it in an ice bath for 10-15 min. Collect the crystals under reduced pressure using a Hirsch funnel, and then wash the filter cake with 0.5 mL of cold ethyl acetate. Dry the product on a porous clay plate or filter paper. 

Purification and Characterization. The product normally is suffidently pure for direct characterization. Weigh the caffeine 5-nitrosalicylate and calculate the percent yield. Determine the melting point and compare your value with that reported above. 

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Isolation and Characterization of a Natural Product Caffeine and Caffeine 5-Nitrosalicylate... 

The infirared spectrum of 5-nitrosalicylic acid (Fig. 6.26) possesses fhe typical broad medium band found in acid dimers (908 cm ). In the caffeine 5-nitrosalicylate complex, however, this band is missing. Suggest a reason why the 908-wavenumber peak vanishes. 

This material may be used to prepare the caffeine 5-nitrosalicylate derivative (see Experiment [IIB]). 

Purpose. To extract the active principle, an alkaloid, caffeine, from a native source, tea leaves. Caffeine is a metabolite (a product of the living system s biochemistry) found in a variety of plants. We wtU use ordinary tea bags as our source of raw material. This experiment illustrates an extraction technique often used to isolate water-soluble, weakly basic natural products from their biological source (see also Experiment [llA] for another extraction strategy). The isolation of caffeine win also give you the opportunity to use sublimation as a purification technique, since caffeine is a crystalline alkaloid that possesses sufficient vapor pressure to make it a good candidate for this procedure. In addition, the preparation of a derivative of caffeine, its 5-nitrosalicylate salt, will be carried out. This latter conversion takes advantage of the weakly basic character of this natural product. 

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