DRUGS AND THERAPEUTICS

Drugs And Therapeutics

Drugs And Therapeutics

Introduction

The uses of acetylsalicylic acid are numerous and important. The synthesis of acetylsalicylic acid (3), methyl salicylate (5), and methyl benzoate (7) were conducted through the use of Fischer Esterification. Fischer Esterification is one method used to synthesize the products below. The isolated yields of the products were 96.6% (3), 44.3% (5), 75.3% (7). Compound (3) was fairly pure judging by the results from the melting point, IR, and the results from Trinder's test. The synthesis of product (5) did not result in the desired product, and instead gave back starting material. Product (7) had a very good RI reading, which pointed toward a pure product. This conclusion was confirmed after reading the results from the IR and MS. Electrophilic substitution was used in order to synthesize 5-nitrosalicylic acid (8). The isolated yield for (8) was 74.4%. According to the melting point and IR, product (8) was not pure.

Discussion

Acetylsalicylic acid, more commonly known as aspirin, is a commonly used analgesic. When taken orally, this compound hydrolyzes into salicylic acid in the intestines.1 It isn't until about one to two hours that the salicylic acid levels even appear in the plasma.2 Once in the plasma, this acid has a half life of about six hours. The absorption of this medicine, and its bioavailability depends on many factors. Some of which are how much food is in the stomach, the gastric pH, and also other physiological factors. Upon entering the body, the aspirin is distributed throughout all of the tissues and fluids including breast milk and fetal tissue. owever, the highest levels are in the plasma, the liver, the renal cortex, the heart, and the lungs.

In this lab, methyl salicylate and methyl benzoate were also synthesized. To do so, Fischer Esterification was conducted. For the acetylsalicylic acid, hydrolysis was carried out with the use of a steam bath. The methyl salicylate and methyl benzoate came about through refluxing, which was followed by extraction of the desired compound through the use of a separatory funnel.

Electrophilic aromatic substitution was used in order to synthesize 5-nitrosalicylic acid (8). More specifically, aromatic nitration occurred. In this reaction, an electrophile replaces another group, which is usually hydrogen. In this case, an NO2 group was added to the aromatic portion of the salicylic acid (1). Because the carboxylic acid portion of this compound is electron withdrawing, it is deactivating, which means that the NO2 group will add to the meta position of the aromatic. This nitration can be done in the lab simply using salicylic acid (1) and concentrated nitric acid.

Chemistry Synthesis

Fischer Esterification was used to synthesize the first three products. Fischer Esterification requires a carboxylic acid, an alcohol, and a catalytic amount of acid. This reaction will form an ester. When synthesizing acetyl salicylic acid (3), salicylic acid (1) reacted with acetic anhydride (2) and a catalytic amount of concentrated sulfuric acid. A scheme for this reaction is given below (Figure ...