Naproxen sodium preparations

The phase transformation relationships for the solvatomorphs of naproxen sodium have been reported [71], The dihydrate phase is obtained upon crystallization from water, and a monohydrate phase could be prepared by the dehydration of the dihydrate phase in a desiccator (RH = 0%) for two days. The anhydrate phase could be obtained from either the monohydrate or dihydrate by drying the substance in an oven at 120 °C for two hours. Thermal analysis data was used to demonstrate the existence of two types of water in the dihydrate phase, and that each could be removed at a characteristic temperature. 

The standard compounds will all be available as solutions of 1 g of each dissolved in 20 mL of a 50 50 mixture of methylene chloride and ethanol. The purpose of the first reference plate is to determine the order of elution (R values) of the known substances and to index the standard reference mixture. Several of the substances have similar Revalues, but you will note a different behavior for each spot with the visualization methods. On the sample plate, the standard reference mixture will be spotted, along with Naproxen sodium and several solutions that you will prepare from commercial analgesic tablets. These tablets will each be crushed and dissolved in a 50 50 methylene chloride-ethanol mixture for spotting. 

A stereoselective GC method for determination of etodolac enantiomers in human plasma and urine was first reported as a preliminary method [35], and then as a validated method [36]. Sample preparation involved addition of (S)-(+)-naproxen (internal standard) and sodium hydroxide to diluted plasma or urine. The samples were washed with diethyl ether, acidified with hydrochloric acid, and extracted with toluene. ( )-(+)-naproxen was used as a derivatizing agent to form diastereomeric derivatives of etodolac. The gas chromatograph system used in this work was equipped with fused-silica capillary column (12 m x 0.2 mm i.d.) coated with high-performance cross-linked methylsilicone film (thickness 0.33 pm) and a nitrogen-phosphorous detector. The operating conditions were injector 250°C detector 300°C column 100-260°C (32 °C/min). 

Sample preparation Mix 300 pL of a 30 pM solution in dichloromethane with 10 pL 20 mM l-(6-methoxy-2-naphthyl)ethyl isothiocyanate in anhydrous dichloromethane and 50 pL 0.1% triethylamine in dichloromethane, vortex thoroughly, heat at 50° for 1.5 h, inject an aliquot. (Synthesize l-(6-metho -2-naphthyl)ethyl isothiocyanate as follows (protect from light). Dissolve 500 mg (S)-(+)-naproxen in 50 mL dry toluene, slowly add 5 mL freshly distilled thionyl chloride, reflux for 1 h, evaporate to dryness under vacuum, dry the acyl chloride (mp 87.5°) under vacuum over KOH for 2 days. Dissolve 0.5 mmoles acyl chloride in 5 mL acetone, stir at 0°, add 0.6 mmoles sodium azide dissolved in ice water, stir at 0° for 30 min, add 10 mL ice-cold water, filter, dry solid in a desiccator under vacuum. Dissolve the solid in 1 mL toluene or dichloromethane (dried over 3 A molecular sieve), reflux for 10 min, evaporate, store resulting isocyanate (mp 51°) under vacuum over a desiccant. Dissolve 0.5 mmole isocyanate in 5 mL acetone, add 20 mL 8.5% phosphoric acid, heat to 80° for 1.5 h, adjust to pH 13, extract with diethyl ether dichloromethane 4 1. Wash the organic layer twice with water, dry over anhydrous sodium sulfate, evaporate to dryness, dissolve in 1 mL toluene, evaporate to give the amine from... 

The sodium salt of (5)-naproxen is the active ingredient in Aleve and a score of other over-the-counter nonsteroidal anti-inflammatory preparations. 

In this experiment, you will be preparing the carboxylic acid, naproxen, rather than the sodium salt, sodium naproxen. As is often the case with pharmaceuticals. 

Give a balanced equation for the reaction of naproxen with sodium hydroxide to prepare sodium naproxen. 

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