Commercial TBHQ is produced by reacting hydroquinone with tert-butanol or isobutylene. Here is a detailed manufacturing process between hydroquinone and tert-butanol from a China manufacturer (1).

The following is the brief reaction equation:


TBHQ manufacturing reaction

Specification
Appearance    White or tan powder with a light characteristic odour.
Other names    Tert-butylhydroquinone, tert-butyl-1,4-benzenediol
CAS number    1948-33-0
Chemical formula    C10H14O2
Molecular weight    166.220
Stability    With high thermal stability, no discoloration in the presence of metal ions (e.g. iron, copper).
Solubility    practically insoluble in water, easy to dissolve in oils & fats and organic solvents