Phenol → 2-Hydroxy-9H-thioxanthen-9-one

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Reaction Steps

An example of a conventional synthetic route to 2-carboxymethoxythioxanthone involves three stages. Firstly, phenol is reacted with dithiobisbenzoic acid to produce 2-hydroxythioxanthone in a 60% yield. Secondly, the 2-hydroxythioxanthone is reacted with ethyl bromoacetate to produce the ethyl ester of 2-carboxymethoxythioxanthone in 75% yield. Thirdly, the ester is hydrolysed by acidification to produce the desired product in 90% yield. These three stages form an inefficient and time-consuming process to provide a product that is a dark colour, contains impurities and by-products and is produced with only an overall yield of 40% from the starting material.

Provenance & Evidence