Question

In Chapter 14, we saw that Agent Orange contains (2,4,5-trichlorophenoxy) acetic acid, called 2,4,5-T. This compound is synthesized by the partial reaction of 1,2,4,5-tetrachlorobenzene with sodium hydroxide, followed by a reaction with sodium chloroacetate, ClCH2CO2Na.

(a) Draw the structures of these compounds, and write equations for these reactions.

(b) One of the impurities in the Agent Orange used in Vietnam was 2,3,7,8-tetrachlorodibenzodioxin (2,3,7,8-TCDD), often incorrectly called “dioxin.” Propose a mechanism to show how 2,3,7,8-TCDD is formed in the synthesis of 2,4,5-T.

(c) Show how the TCDD contamination might be eliminated, both after the first step and on completion of the synthesis

Short answer

Structure of 2,4,5-T

Formation of 2,4,5-T

Structure of 2,3,7,8-tetrachlorodibenzodioxin

Formation of 2,3,7,8-tetra chloro dibenzodioxin

Step-by-step solution

2,4,5-trichloro phenoxy acetic acid

2,4,5-trichloro phenoxy acetic acid is a herbicide used in agriculture. It is a synthetic auxin and is used to defoliate broadleaf plants. However, it use has been restricted due to some toxic effects.

Structure and reaction of the following compounds

1,2,4,5-tetrachloro benzene reacts with NaOH and sodium chloroacetate to form a product that reacts with HCl to form 2,4,5-trichloro phenoxy acetic acid as the desired product.

Structure of 2,4,5-T

Formation of 2,4,5-T