Question

What is the balanced chemical equation for the synthesis of guaifenesin? Guaiacol is reacted with NaOH and 3-chloro-1,2-propanediol to yield guaifenesin.

Answer 1

1. Guaifenesin is used as an expectorant in many common cold & cough syrups, including Benylin, Robitussin & Novahistex.
2. It loosens and thins bronchial secretions, which leads to more productive cough. It is also available in tablet form both over-the-counter, and in a higher dose prescription form.
3. The compound is administered in racemic form, although it has been suggested that the (S)-(+)-enantiomer is more potent. The synthesis of guaifenesin follows Williamson ether synthesis.
4. (±)-3-chloro-1,2-propane-diol will be allowed to react with the conjugate base of Guaicol (2-methoxyphenol) via an SN2 reaction to provide guaifenesin as a racemic mixture. The same material will also be isolated from over the counter tablets via a simple extraction.
5. The chemical equation for the synthesis of guaifenesin from the reaction between sodium hydroxide, 3-chloro-1,2-propanediol with guaiacol is as follows:
   
   OH Ci OH HO O NaOH OH ethanol Guaifenesin