ArylOCOOaryl

ArylOCOOaryl refers to the diaryl carbonates, a class of organic esters consisting of two aryl groups connected by a carbonate linkage (Ar–O–CO–O–Ar). The term encompasses both symmetrical diaryl carbonates (where the two aryl groups are the same) and unsymmetrical variants (where the aryl groups differ). The aryl rings and their substituents influence properties such as reactivity, solubility, and hydrolytic stability.

Structure and synthesis

The core motif is a carbonate group flanked by two aryl oxygens. Diaryl carbonates are typically prepared by reactions involving phenols and carbonate sources. The traditional route uses phosgene, for example ArOH reacting with COCl2 to give Ar–O–CO–O–Ar. Phosgene-free syntheses are also used, including transesterification routes (for example processes that exchange ester groups between phenyl chloroformates and phenols) and catalytic oxidative carbonylation methods that form diaryl carbonates from phenols, CO, and oxidants.

Reactions and properties

Diaryl carbonates are relatively stable under dry, mild conditions but hydrolyze in the presence of moisture to release phenols and carbon dioxide. They can undergo transesterification with other phenols to form mixed diaryl carbonates, enabling access to a variety of unsymmetrical products. Their physical state ranges from crystalline solids to liquids, depending on substituents on the aryl rings.

Applications

The principal industrial use of diaryl carbonates is as monomers or intermediates in the production of polycarbonates. In the transesterification (phosgene-free) route to polycarbonates, diaryl carbonates such as diphenyl carbonate react with diols (notably bisphenol A derivatives) to yield polycarbonate polymers and phenol as a by-product. They also serve as reagents and intermediates in organic synthesis and can function as solvents or additives in specialized applications.

Examples

Diphenyl carbonate is the most common diaryl carbonate. Other examples include di(o-tolyl) carbonate and di(naphthyl) carbonate.