This invention relates to the production of terephthalic acid by 1) cycloaddition of 2,5 substituted furan (such as 2,5-bis hydroxymethylfuran or 5-hydroxymethylfurfural) and ethylene, and 2) the subsequent oxidation of the dehydrated cycloaddition product to terephthalic acid. The invention relates more particularly to overall biobased pathways for making terephthalic acid from carbohydrates such as hexoses (e.g., glucose or fructose).