Editing Retinol (section)

===Industrial synthesis===
[[File:Ionone beta.svg|thumb|left|class=skin-invert-image|β-ionone ring]]
Retinol is made industrially via [[total synthesis]] using either a method developed by [[BASF]]<ref name="β-Carotin-1">{{cite patent | inventor = Wittig G, Pommer H | country = DE | number = 954247 | gdate =  13 December 1956 | title = Verfahren zur Herstellung von best-Carotin bzw. 15,15'-Dehydro-beta-carotin | postscript = . }}</ref><ref name="β-Carotin-2">{{cite patent | country = US | number = 2917524 | inventor = Wittig G, Pommer H | title = Compounds of the vitamin A series | gdate = 1959 | assign1 = Badische Anilin- & Soda-Fabrik Akt.-Ges. }}</ref> or a [[Grignard reaction]] utilized by [[Hoffman-La Roche]].<ref>{{cite patent|country = US |number = 2609396 |title = Compounds with the carbon skeleton of beta-carotene and process for the manufacture thereof |pubdate = 2 September 1952 |inventor = Herloff IH, Horst P | postscript = . }}</ref> The two major suppliers, DSM and BASF, are believed to use total synthesis.<ref name="Parker2016"/>

The world market for synthetic retinol is primarily for animal feed, leaving approximately 13% for a combination of food, prescription medication, and dietary supplement use.<ref name="Parker2016"/> The first industrialized synthesis of retinol was achieved by the company Hoffmann-La Roche in 1947. In the following decades, eight other companies developed their own processes. [[β-Ionone]], synthesized from acetone, is the essential starting point for all industrial syntheses. Each process involves elongating the unsaturated carbon chain.<ref name="Parker2016">{{cite journal|vauthors=Parker GL, Smith LK, Baxendale IR |title=Development of the industrial synthesis of vitamin A |journal=Tetrahedron |volume=72 |issue=  13|pages=1645–52 |date=February 2016 |pmid= |doi=10.1016/j.tet.2016.02.029}}</ref> Pure retinol is extremely sensitive to oxidization and is prepared and transported at low temperatures and oxygen-free atmospheres. When prepared as a dietary supplement or food additive, retinol is stabilized as the [[ester]] derivatives [[retinyl acetate]] or [[retinyl palmitate]]. Before 1999, three companies, Roche, [[BASF]], and [[Rhone-Poulenc]] controlled 96% of global vitamin A sales. In 2001, the European Commission imposed total fines of 855.22 Euros on these and five other companies for their participation in eight distinct market-sharing and price-fixing cartels that dated back to 1989. Roche sold its vitamin division to [[DSM (company)|DSM]] in 2003. DSM and BASF have the major share of industrial production.<ref name="Parker2016"/>