A breakthrough synthetic method for Cyclohexyl Acetate, a vital compound extensively used in fragrances and industrial solvents, has been developed, offering significant improvements in yield, environmental impact, and operational simplicity compared to traditional methodologies. This new process effectively addresses the long-standing issues of corrosion, poor selectivity, complex waste treatment, and environmental pollution associated with conventional sulfuric acid catalysis.

Cyclohexyl acetate, a colorless to pale yellow oily liquid with a distinct banana or apple aroma, is indispensable in fragrance formulations for food, beverages, cosmetics, and perfumes, especially for replicating apple, banana, blackcurrant, and raspberry notes. Furthermore, its excellent solvent properties make it valuable in resins, coatings, and paints. The urgent need for a cleaner, more efficient production method has driven this innovation.

The core innovation lies in the deployment of copper p-toluenesulfonate as a highly effective and reusable catalyst. The process comprises two key stages. First, copper p-toluenesulfonate is synthesized by refluxing copper oxide and p-toluenesulfonic acid in a molar ratio range of 3:4 to 1:1 in deionized water for 3-5 hours. The resulting blue crystals are filtered, dried, recrystallized from ethanol 2-4 times, and dried to constant weight under vacuum.

Second, the esterification reaction is carried out by combining cyclohexanol and acetic acid (molar ratio from 1.0:1 to 1.6:1) in a flask equipped with a Dean-Stark trap (water separator), thermometer, and reflux condenser. To this mixture, the catalyst copper p-toluenesulfonate (0.4 to 1.6 g per 0.2 mol acetic acid) and optionally cyclohexane as an entraining agent (azeotrope former) (0 to 30 ml per 0.2 mol acetic acid) are added. The reaction mixture is heated under reflux for an efficient 10 to 80 minutes. The reaction pathway is the standard acid-catalyzed esterification: Cyclohexanol + Acetic Acid ⇌ Cyclohexyl Acetate + Water.

The workup procedure involves neutralizing the reaction mixture through successive washes with water and a 10% sodium bicarbonate solution, followed by a final water wash. After drying, the crude product undergoes distillation, with the pure cyclohexyl acetate (boiling point 170-173°C) collected.

Optimized reaction conditions yield exceptional efficiency. Extensive experimentation identified the optimum parameters: a cyclohexanol to acetic acid molar ratio of 1.4:1, catalyst loading of 1.2 g per 0.2 mol acetic acid, addition of 15 ml cyclohexane per 0.2 mol acetic acid, and a reaction time of 60 minutes. Under these specific conditions, the process consistently achieves an impressive esterification rate of 96.7%. Detailed data revealed how factors influence the outcome: increasing the cyclohexanol ratio boosted yield up to the optimum 1.4:1 ratio (96.7%), declining slightly beyond that. Reaction time was crucial; the yield dramatically rose from 17.9% at 10 minutes to plateau at 96.7% around 60 minutes.

The developed method offers substantial advantages critical for both economic and ecological sustainability. Beyond the high yield, the copper p-toluenesulfonate catalyst demonstrates excellent stability and reusability, significantly lowering long-term costs and minimizing chemical waste generation. The reaction time is drastically shortened compared to conventional methods, and the simplified post-reaction purification steps streamline the entire workflow. Most notably, this process eliminates the use of highly corrosive and polluting sulfuric acid, representing a major stride forward in green chemistry for the flavor, fragrance, and chemical industries.