text: An uncommon class of esters are the orthoesters. One of them are the esters of orthocarboxylic acids. Those esters have the formula , where R stands for any group (organic or inorganic) and R stands for organyl group. For example, triethyl orthoformate () is derived, in terms of its name (but not its synthesis) from esterification of orthoformic acid () with ethanol.