Editing Chemistry of ascorbic acid (section)

===Industrial preparation===
[[Image:Synthesis ascorbic acid.svg|thumb|500px|class=skin-invert-image|The outdated but historically significant industrial synthesis of ascorbic acid from glucose via the [[Reichstein process]]]]
Seventy percent of the world's supply of ascorbic acid is produced in China.<ref name="Vantage Market Research-2022" /> Ascorbic acid is prepared in industry from [[glucose]] in a method based on the historical [[Reichstein process]]. In the first of a five-step process, glucose is catalytically [[hydrogenation|hydrogenated]] to [[sorbitol]], which is then [[redox|oxidized]] by the [[microorganism]] ''[[Acetic acid bacteria#Acetobacter|Acetobacter]] suboxydans'' to [[sorbose]]. Only one of the six hydroxy groups is oxidized by this enzymatic reaction. From this point, two routes are available. Treatment of the product with [[acetone]] in the presence of an acid [[Catalysis|catalyst]] converts four of the remaining [[hydroxyl]] groups to [[acetal]]s. The unprotected hydroxyl group is oxidized to the carboxylic acid by reaction with the catalytic oxidant [[TEMPO]] (regenerated by [[sodium hypochlorite]]{{snd}} [[bleach]]ing solution). Historically, industrial preparation via the Reichstein process used [[potassium permanganate]] as the bleaching solution. Acid-catalyzed hydrolysis of this product performs the dual function of removing the two acetal groups and [[lactone|ring-closing lactonization]]. This step yields ascorbic acid. Each of the five steps has a yield larger than 90%.<ref>{{Ullmann | author = Eggersdorfer, M. |display-authors=etal| title = Vitamins | doi = 10.1002/14356007.a27_443 }}</ref>

A biotechnological process, first developed in China in the 1960s but further developed in the 1990s, bypasses acetone-protecting groups. A second [[genetically modified]] microbe species, such as mutant ''[[Erwinia]]'', among others, oxidises sorbose into 2-ketogluconic acid (2-KGA), which can then undergo ring-closing lactonization via dehydration. This method is used in the predominant process used by the ascorbic acid industry in China, which supplies 70% of the world's ascorbic acid.<ref name="Vantage Market Research-2022">{{cite press release |url=https://www.globenewswire.com/en/news-release/2022/11/08/2550571/0/en/Global-Vitamin-C-Market-Size-Share-to-Surpass-1-8-Bn-by-2028-China-Produces-80-of-Commercial-Vitamin-C-Vantage-Market-Research.html |title=Vantage Market Research: Global Vitamin C Market Size & Share to Surpass $1.8 Bn by 2028 |date=8 November 2022 |website=Globe Newswire |access-date=21 December 2023}}</ref> Researchers are exploring means for one-step fermentation.<ref>{{cite journal |vauthors=Zhou M, Bi Y, Ding M, Yuan Y |title=One-Step Biosynthesis of Vitamin C in Saccharomyces cerevisiae |journal=Front Microbiol |volume=12 |issue= |pages=643472 |date=2021 |pmid=33717042 |pmc=7947327 |doi=10.3389/fmicb.2021.643472 |url= |doi-access=free }}</ref><ref>{{cite journal |vauthors=Tian YS, Deng YD, Zhang WH, Yu-Wang, Xu J, Gao JJ, Bo-Wang, Fu XY, Han HJ, Li ZJ, Wang LJ, Peng RH, Yao QH |display-authors=5 |title=Metabolic engineering of Escherichia coli for direct production of vitamin C from D-glucose |journal=Biotechnol Biofuels Bioprod |volume=15 |issue=1 |pages=86 |date=August 2022 |pmid=35996146 |pmc=9396866 |doi=10.1186/s13068-022-02184-0 |url= |doi-access=free |bibcode=2022BBB....15...86T }}</ref>