INTRODUCTION In experimental chemistry, especially synthetic, a lot of harmful solvents are used to improve reaction conditions and toxic by-products are often generated .
These chemicals are a source of pollution and are hazardous to the ecosystem.
The scratching process gives the aspirin a crystalline surface on which it can grow.
The melting point determination gives an idea of purity as the purer a substance is the more defined it’s melting point is.
In classical synthesis, salicylic acid and acetic anhydride are refluxed with a strong acid in benzene. Middle As shown, the two products of the reaction are aspirin and acetic acid.
The ASA is characterized as white crystals with the smell of vinegar caused by the acetic acid.Furthermore, by Lewis theory, the lone pairs on the oxygen atoms also make sodium carbonate a base. 5 - base-catalyzed reaction with salicylic acid The ionic character of the sodium salicylate makes attack on the carbonyl of acetic anhydride favourable.In figure 5, the carbonate abstracts a proton from the carboxylic group to form bicarbonate because this functional group is the stronger acid. This forms an intermediate that requires a proton to hydrolyze and form acetic acid. 6 - Attack on acetic anhydride The molecule produced in figure 6 is clearly very unstable. In the microwave synthesis spectrum, the resolution was quite good and this phenomenon can be observed.With the conventional heating method, a 52.4% yield was obtained, while an 83.5% yield was obtained by microwave heating.The high-yielding microwave irradiation method also displayed higher purity with a melting temperature range of 128-132�C (lit.Aspirin has been with us for long time – the first documented reports of its use occurred over 2000 years ago.That said, the aspirin may not be in the form that you instantly think of (ie, a tablet) but it has been used all the same.Given environmental concerns, chemists have been redesigning synthetic schemes in order to minimize the use and production of hazardous compounds .In the synthesis of acetyl salicylic acid (aspirin), abbreviated as ASA, a popular drug, the principles of green chemistry are applied to improve its environmental friendliness.The hot solution will be saturated, meaning that crystals will form out if the solution as it cools down and can therefore hold less solute.It is common practice to scratch the inside of the vessel with a glass rod, below the level of solvent to encourage crystals to grow.