This compound then oxidized in air to form ethylboronic acid. Several synthetic routes are now in common use, and many air-stable boronic acids are commercially available. Boronic acids typically have high melting points. They are prone to forming anhydrides by loss of water molecules, typically to give cyclic trimers. Boronic acids can be obtained via several methods. The most common way is reaction of organometallic compounds based on lithium or magnesium (Grignards) with borate esters. For example, phenylboronic acid is produced from phenylmagnesium bromide and trimethyl borate followed by hydrolysis  Another method is reaction of an arylsilane (RSiR3) with boron tribromide (BBr3) in a transmetallation to RBBr2 followed by acidic hydrolysis. A third method is by palladium catalysed reaction of aryl halides and triflates with diboronyl esters in a coupling reaction. An alternative to esters in this method is the use of diboronic acid or tetrahydroxydiboron ([B(OH2)]2). Boronic esters are esters formed between a boronic acid and an alcohol. The compounds can be obtained from borate esters by condensation with alcohols and diols. Phenylboronic acid can be selfcondensed to the cyclic trimer called triphenyl anhydride or triphenylboroxin. Compounds with 5-membered cyclic structures containing the C–O–B–O–C linkage are called dioxaborolanes and those with 6-membered rings dioxaborinanes. Boronic acids are used in organic chemistry in the Suzuki reaction. In this reaction the boron atom exchanges its aryl group with an alkoxy group from palladium. ][\text{Base}] R1-R2}\\  In the Chan–Lam coupling the alkyl, alkenyl or aryl boronic acid reacts with a N–H or O–H containing compound with Cu(II) such as copper(II) acetate and oxygen and a base such as pyridine forming a new carbon–nitrogen bond or carbon–oxygen bond for example in this reaction of 2-pyridone with "trans"-1-hexenylboronic acid:  The reaction mechanism sequence is deprotonation of the amine, coordination of the amine to the copper(II), transmetallation (transferring the alkyl boron group to copper and the copper acetate group to boron), oxidation of Cu(II) to Cu(III) by oxygen and finally reductive elimination of Cu(III) to Cu(I) with formation of the product.