Introduction

Propyl propionate (ProPro) is an important solvent useful in many industrial applications like paints and coatings, cleaning fluids, and personnel care. It is gaining importance because of its ability to replace hydrocarbon solvents, especially the benzene, toluene and xylene (BTX) streams. The minimum purity required of the compound is > 99 mol %. Because it is substantially soluble in water and alcohol, obtaining pure ProPro is difficult. Industrially, ProPro is produced by direct esterification of 1 - propanol (ProOH) with Propionic acid (ProAc) in the liquid phase using an acid catalyst[1].

Chemical property

Propyl propionate is a colourless liquid with a pungent, ‘fruity’ odour. According to the H-phrases in its material safety data sheet,?propyl propionate poses a health risk similar to acetone and less than IMS. As propyl propionate is a novel solvent in conservation, we continue to employ additional health and safety controls around its use.?It is a propanoate ester’ resulting from the formal condensation of the hydroxy group of propanol with the carboxy group of propanoic acid. It has the molecular formula C6H12O2.

Uses

n-Propyl Propionate (Propyl propionate) is an ecofriendly product applied in drugs and ink production, polymerization reactions, and the coating industry, and it is used as an additive for food and perfume[2]. The U.S. Environmental Protection Agency considers ProPro a harmless air pollutant, and it is acknowledged as a biodegradable and non-toxic product. It may be used as an additive for food and perfume due to its pleasant smell and absence of toxicity. ProPro can be synthesized by a heterogeneous esterification reaction of 1-propanol with propionic acid, which also yields water. From this point on, A and B are the reactants 1-propanol and propionic acid, and C and D are the products’ water and n-propyl propionate, as in (1). k1 and k?1 are the kinetic constants for the formation and consumption of ProPro, respectively. 1-propanol might also undergo secondary reactions such as etherification and dehydration, producing di-n-propyl ether and propane. These side reactions are undesired due to economic and safety issues, as propane is an easily flammable gas. In order to avoid these side reactions, Amberlyst 46 is employed as a heterogenous catalyst due to its ester prioritization and adsorption of water that shift the equilibrium toward products.

References

[1] Reshma R. Devale, Y. S. Mahajan. “Separation of N-propyl propionate from its highly non-ideal reaction mixture: Distillation using rigorous simulation.” Materials Today: Proceedings 81 1 (2023).

[2] R. Santos. “A Complete Heterogeneous Model for the Production of n-Propyl Propionate Using a Simulated Moving Bed Reactor.” Separations (2022).