Titanium dioxine

Anhydrous aluminum chloride, AIQ, is manufactured primarily by reaction of chlorine [7782-50-5] vapor with molten aluminum and used mainly as a catalyst in organic chemistry ie, in Friedel-Crafts reactions (qv) and in proprietary steps in the production of titanium dioxine [13463-67-7] Ti02, pigment. Its manufacture by carbochlorination of alumina or clay is less energy-intensive and is the preferred route for a few producers (19). 

A similar type of acid-catalyzed condensation of aldehydes with 4-methylene-2-oxetanone (diketene), giving 4-oxo-6-methyl-l,3-dioxins, has been patented (73GEP2149650). However, other work has established that <5-hydroxy-/3-keto acids or unsaturated keto acids are formed as the principal products (equation 24) (78CPB3877, 78CL409). The latter reaction probably involves electrophilic attack of the protonated aldehyde on the nucleophilic exocyclic methylene carbon atom of the diketone. A closely related reaction of acetals with diketene, catalyzed by titanium tetrachloride, gives the corresponding <5-alkoxy-/3-keto esters (74CL1189). 

Related Reagents. 10,2-Camphorsultam (/ )-2-t-Butyl-6-methyl-4//-l,3-dioxin-4-one (/ )-(+)-(t)-Butyl 2-(/ -Tolysulfin-yl)propionate Chloro(cyclopentadienyl)bis[3-0-( 1,2 5,6-do-0-isopropylidene-a-D-glucofuranosyl)]titanium lO-Dicyclohexyl-sulfonamidoisobomeol Diisopinocampheylboron Trifluoro-methanesulfonate (R,/ )-2,5-Dimethylborolane 2-Hydroxy-... 

Eastman have patented a range of techniques for recovering monomers from aromatic polyesters. Initial intellectual property dealt with generalised schemes for methanolysis catalysed by zinc acetate, tin salts or titanium tetraisopropoxide [157, 158]. A major effort was made to develop a process which may be described as high-pressure methanolysis, in which superheated methanol is passed through a solution of scrap PET in oligomers of the same material [159-166]. Various refinements have also been made to the basic process, including addition of trace amounts of base to the reaction to prevent formation of dioxin [167], and recovery of additional aliquots of DMT from the EG stream and purification of the latter product [168-171]. 

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