Vitamin precursor synthesis

BASE in Ludwigshafen, Germany, carried out process development for a reaction as part of a multistep process, finally yielding a vitamin [32,33]. This involved short-temperature processing ( 4s) that simply was not possible using macroscopic bench-scale apparatus. In the latter case, almost 50% of the reaction heat was 

The reactants and the product were not disclosed in the open hterature [32,33]. Concentrated sulfuric add is present in quantitative amounts besides the organic solvent, so a liquid/liquid process results. The reactant quickly forms an intermediate that again quickly reacts to give the product. Thermally induced side reactions occur at each stage. 

Retinol (Vitamin A form) was synthesized by ester cleavage in a microreactor-based system at Sigma-Aldrich, Switzerland [34]. 

A total of 800 g/day of product was synthesized and the advantages compared to batch technology were evident on a 500 g scale and are shown in Table 11.2. 

By transferring the batch synthesis routine into a flow chemistry process in a microreactor, the yield of the reaction was improved to 70%, now giving a constant output of 70% product each time the synthesis is performed [34]. This improvement 

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DuPont s phosgene synthesis in a micro reactor BASE S vitamin precursor synthesis developments in the bio field prognosis on market volume in 2000 [227]. 

Drivers for Performing Vitamin Precursor Synthesis in Micro Reactors... 

Beneficial Micro Reactor Properties for Vitamin Precursor Synthesis... 

Vitamin Precursor Synthesis Investigated in Micro Reactors Organic synthesis SS [OS S8] Synthesis of a vitamin precursor... 

Vitamin precursor synthesis - production of P-ionone (http //www.clarkson.edu/chemeng/ faculty pages/jachuck.html) [57,58]... 

Vitamin precursor synthesis Micro-reaction system with integrated static mixer heat exchangers, reaction channels and delay loop Residence time of 30 s, yield of 95%, amount of byproducts reduced by > 50%... 

Endogenous vitamin precursor 7-Dehydrocholesterol, an intermediate in cholesterol synthesis, is converted to cholecalciferol in the dermis and epidermis of humans exposed to sunlight. Preformed vitamin D is a dietary requirement only in individuals with limited exposure to sunlight. 

Researchers at BASF have shown that microreactors can be utilized that give access to operating conditions that cannot be realized by means of macroscopic equipment. They succeeded in improving yield and selectivity in a highly exothermal two-phase reaction in connection with the synthesis of a vitamin precursor. At Degussa company, a microreactor test facility for proprietary reactions is under construction. The major focus in this context is the implementation of microreaction devices as powerful tools for process development and, in particular, for the evaluation of new reaction pathways. 

The precursor for vitamin B12 synthesis is uroporphyrinogen 111, the common precursor for aU porphyrins, including heme and chlorophyll. Uroporphyrinogen III is synthesized by condensation between succinyl coenzyme A (CoA) and glycine to yield 5-aminolevulinic acid. Two molecules of (5-amino-levulinic acid then condense to form the pyrrole phorphobilinogen, and four molecules of porphobilinogen condense to yield uroporphobilinogen III. 

Vitamin K activity is associated with at least two distinct natural substances, designated as vitamin K, and vitamin Kj. Vitamin K or phylloquinone (phytonadione) is 2-methyl-3-phytyl-l,4-naphthoquinone it is found in plants and is the only natural vitamin K available for therapeutic use. Vitamin K is actually a series of compounds (the mena-quinones) in which the phytyl side chain of phylloquinone has been replaced by a side chain built up of 2 to 13 prenyl units. Considerable synthesis of menaquinones occurs in Gram-positive bacteria indeed, intestinal flora synthesize the large amounts of vitamin K contained in human and animal feces. In animals menaquinone-4 can be synthesized from the vitamin precursor menadione (2-methyl-l,4-naphtho-quinone), or vitamin Kj. Depending on the bioassay system used, menadione is at least as active on a molar basis as phylloquinone. 

The bicyclic double lactone (14) was used by Eschenmoser as the precursor for all four heterocyclic rings in his vitamin B12 synthesis. Disconnecting both lactones reveals a ketone (15). 

Ethyl crotonate 3-lonone vitamin A precursor Carotene vitamin A source Shark liver oil vitamin A synthesis Lithium... 

Potassium ascorbate vitamin D source, enriched farina Yeast, dried irradiated vitamin D, pharmaceuticals Cod liver oil vitamin deriv., hair care Panthenyl triacetate vitamin deriv., lip care Panthenyl triacetate vitamin deriv., massage oils Panthenyl triacetate vitamin deriv., skin care Panthenyl triacetate vitamin deriv., skin care oils Panthenyl triacetate vitamin E precursor synthesis N-Methyl-2-pyrrolidone vitamin E source Wheat (Triticum vulgare) germ oil vitamin E source, food... 

Vitamin E (a) L. F. Tietze, J. Gorlitzer, A. Schuffenhauer, M. HUbner, Eur. J. Org. Chem. 1999, 1075-1084. Enantioselective synthesis of the chromane moiety of vitamin E. (b) L. F. Tietze, J. Gorlitzer, Synlett 1997, 1049-1050. Preparation of enantiopure precursors for the vitamin E synthesis. A comparison of the asymmetric allylation of ketones and the sharpless bishydroxylation. (+)-Hydroxymyoporone (c) L. F. Tietze, C. Wegner, C. Wulff, Chem.-Eur. J. 1999, 5, 2885-2889. First total synthesis and determination of the absolute configuration of the stress factor (+)-hydroxymyoporone. 5,6-Dihydrocineromycin B (d) L. F. Tietze, L. Vblkel, Angew. Chem. Int. Ed. 2001, 40, 901-902. Total synthesis of the macrolide antibiotic 5,6-dihydrocineromycin B. 

Structural drawings of carbohydrates of this type are called Haworth formulas, after the British chemist Sir Walter Norman Haworth (St Andrew s University and the University of Birmingham) Early m his career Haworth contributed to the discovery that carbohydrates exist as cyclic hemiacetals rather than m open chain forms Later he col laborated on an efficient synthesis of vitamin C from carbohydrate precursors This was the first chemical synthesis of a vitamin and provided an inexpensive route to its prepa ration on a commercial scale Haworth was a corecipient of the Nobel Prize for chem istry m 1937... 

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