Editing Tocopherol (section)

==Synthesis==
Naturally sourced d-α-tocopherol can be extracted and purified from seed oils, or γ-tocopherol can be extracted, purified, and methylated to create d-alpha-tocopherol. In contrast to α-tocopherol extracted from plants, which also is called d-α-tocopherol, industrial synthesis creates dl-α-tocopherol. "It is synthesized from a mixture of toluene and 2,3,5-trimethyl-hydroquinone that reacts with isophytol to all-rac-α-tocopherol, using iron in the presence of hydrogen chloride gas as a catalyst. The reaction mixture obtained is filtered and extracted with aqueous caustic soda. Toluene is removed by evaporation and the residue (all rac-α-tocopherol) is purified by vacuum distillation." Specification for the ingredient is >97% pure.<ref>[https://efsa.onlinelibrary.wiley.com/doi/pdf/10.2903/j.efsa.2012.2784 Scientific Opinion on the safety and efficacy of synthetic α-tocopherol for all animal species] (2012) European Food Safety Authority EFSA Journal 2012;10(7):2784</ref> This synthetic dl-α-tocopherol has approximately 50% of the potency of d-α-tocopherol. Manufacturers of dietary supplements and fortified foods for humans or domesticated animals convert the phenol form of the vitamin to an [[ester]] using either [[acetic acid]] or [[succinic acid]] because the esters are more chemically stable, providing for a longer shelf-life. The ester forms are de-esterified in the gut and absorbed as free α-tocopherol.