Lab D: Reduction of Vanillin to Vanillyl Alcohol

Reaction Mechanism of Vanillyl Alcohol

reducing aldehyde of vanillin to vanillyl alcohol

Calculating Limiting Reactant

every molecule of NaBH₄ is 4 H ions; have to multiply the mass of NaBH₄ by 4 to get mass of H ions; the limiting reactant is vanillin

vanillin

aromatic compound found in vanilla extract; commonly used for flavoring, baking, and perfume industry; starting material for L-dopa to treat Parkinson's disease; 152.15 g/mol; 81-83°C; d 1.056 g/mL

vanillyl alcohol

renewable source towards synthesizing biologically active molecules and flavoring ingredients; the African sugarcane moth and Leaffooted pine seed bug use this for chemical communication channels.

sodium borohydride (NaBH₄)

reducing agent; good source of hydride ions; hydride ions is a good nucleophile toward the carbonyl group; LiAlH₄ is extremely reactive with water, but NaBH₄ reacts slowly with water; count moles as H's provided, so 4 moles. MW: 154.16g/mol; d: 1.07 g/mL

HCl

reacts with excess NaBH₄ and produces hydrogen gas and boric acid; vanillyl alcohol then precipitate from solution

IR Spectra

Vanillin: OH on aromatic ring stretch

Aldehyde C=O stretch

Aromatic ring stretch

C=C ring stretch

Vanillyl Alcohol: OH on aromatic ring stretch

Absence of aldehyde C=O stretch

New stretch from CH2-OH group

Aromatic ring stretch

C=C ring stretch

ratio of eluent

4 ethyl acetate: 6 hexane