To a 250 mL round bottom flask was added the trans-cinnamic acid, (37,04 g, 0.25 mol, 1 equiv.),  absolute ethanol¹ (51.75 g, 1.125 mol, 4.5 equiv.) and benzene (50 mL, 5 M in trans-cinnamic acid ). The flask was equipped with a stirbar, a soxhlet with cellulose membrane insert (containing 25 g of MgSO₄), and a reflux condenser. The flask was heated to ≈ 40 ^oC in oil bath and concentrated H₂SO₄ (2.56 mL, 0.0475mol, 0.19 equiv.) was added all at once via a syringe. The solution was heated to reflux (oil bath at 120 ^oC and allowed to stir overnight. The solution was then diluted with ether (≈100 mL). The mixture was transferred to a separatory funnel and washed with 3 X 100 mL of a 10% w.t. sodium bicarbonate solution (CAUTION: CO₂ gas is evolved). The organic layer was then washed with deionized water (≈100 mL), brine (≈100 mL), and dried with Na₂SO₄. The solvent was removed in vacuo by rotary evaporation to afford ethyl cinnamate as a clear yellow oil (38.49 g, 87%)².

1. This procedure has been found to be quite general. Many other types of alcohols (methyl, propyl, isopropyl) all seem to be compatible. Likewise, the acid can varied without compromising yields.
2.  In most cases, the product was found to by completely pure by NMR. In situations when this was not the case (particularly with other acids), the product was purified by vacuum distillation.