Dow synthesis of 2,4-D and MCPA.

2,4-D and MCPA are produced by the Dow Process. In the USA, 2,4-D is preferred to MCPA, but the reverse is true in the UK; in the rest of Europe there no preference. The main reason for this is historical, and was the availability of the starting phenol when the compounds were introduced in the 1940s. o-creosol was readily available in the UK from coal tar, whereas in the USA synthetic phenol was available.

Synthesis of 2,4-D.

Synthesis of MCPA.