What substance is used in the industrial preparation of methyl diantilis to reduce the aldehyde group of 3-ethoxy-4-hydroxybenzaldehyde?

            Sodium Borohydride (NaBH₄)

Explanation:

                    Methyl diantilis (2-Ethoxy-4-(methoxymethyl)phenol) is a fragrance compound which smells like Vanilla. This compound is being synthesized from 3-ethoxy-4-hydroxybenzaldehyde also known as Ethyl Vanillin in two steps.

Step 1: Reduction of Aldehydic Group on Ethyl Vanillin:

The benzaldehyde derivative is treated with a mild reducing agent i.e. NaBH₄ (Sodium Borohydride). NaBH₄ is a source of Hydride (H⁻) ion and undergoes nucleophilic substitution reaction yielding 2-ethoxy-4-(hydroxymethyl)phenol.

Step 2: Etherification of 2-ethoxy-4-(hydroxymethyl)phenol:

In the second step 2-ethoxy-4-(hydroxymethyl)phenol is treated with Methanol in the presence of strong acidic polymeric resin known as Amberlyst-15-wet resulting in the formation of Methyl diantilis as shown in attached figure.

dynamic equilibrium is the answer.

6.4 cm (max) - 25 cm (min)