Question

The antioxidants BHA and BHT are commonly used as food preservatives. Show how BHA and BHT can be made from phenol and hydroquinone.

Short answer

The antioxidants are substances that have the ability to prevent certain cell damages and also protect from free radicals. They are present in fruits and vegetables.

Step-by-step solution

Antioxidants

The antioxidants are substances that have the ability to prevent certain cell damages and also protect from free radicals. They are present in fruits and vegetables.

Synthesis of BHA from phenol and hydroquinone

The synthesis of BHA from phenol is carried initially by nitration then alkylation reduction of nitro to an amino group by (Sn + HCl) then diazotization of the amino group to diazonium chloride and finally by the reaction with sodium methoxide BHA is formed.

Synthesis of BHT by phenol and hydroquinone

In this phenol undergo nitration followed by 2 times alkylation then undergo reduction with Sn and HCl which then undergo diazotization with sodium nitrite and HCl to form diazonium chloride followed by reaction with sodium ethoxide forms BHT as the desired product.