Magnesium perchlorate catalyst

Production of cellulose esters from aromatic acids has not been commercialized because of unfavorable economics. These esters are usually prepared from highly reactive regenerated cellulose, and their physical properties do not differ markedly from cellulose esters prepared from the more readily available aHphatic acids. Benzoate esters have been prepared from regenerated cellulose with benzoyl chloride in pyridine—nitrobenzene (27) or benzene (28). These benzoate esters are soluble in common organic solvents such as acetone or chloroform. Benzoate esters, as well as the nitrochloro-, and methoxy-substituted benzoates, have been prepared from cellulose with the appropriate aromatic acid and chloroacetic anhydride as the impelling agent and magnesium perchlorate as the catalyst (29). 

Can a chiral catalyst containing the same ligand/metal components promote the formation of both enantiomers enantioselectively The bis(oxazoline)magnesium perchlorate-catalyzed asymmetric Diels-Alder reaction [103]... 

Elsewhere, Faita et al. (438) bound the Evans chiral auxiliary to Wang or Merrifield resin for use as a dipolarophile in cycloadditions with C,N-diphenyl-nitrone. Yields on both resins are significantly reduced in comparison to the solution phase reaction (43-20% compared to 95%) but are unaffected by addition of magnesium perchlorate or scandium triflate catalyst. A one-pot process has been reported by Hinzen and Ley (439) that oxidizes secondary hydroxylamines to the... 

Since aluminum chloride often induces polymerization, it is generally replaced by other milder catalysts, such as tin tetrachloride,128-131 zinc chloride,131, 132 magnesium perchlorate,133 ferric... 

Magnesium perchlorate, as catalyst in acetylation of starch, I, 289 Maleic acid,.dihydroxy-, II, 96 III, 149 Malic acid, III, 238, 241 IV, 85 labelled with isotopic C, III, 140, 249 Malonic acid, II, 155 III, 238 protection of enzyme by, V, 54 Maltamylase. See under Amylases. Maltase, IV, 25, 30. See also a-Glucosi-dase. 

Magnesium perchlorate has been used as a catalyst for the synthesis of benzothiazepines 153 from chalcones and 2-aminothiophenol <07JHC541> while derivatives 154 using 3-cinnamoyl coumarin as the a,p-unsaturated ketone have also been synthesised <07JHC145>. The reaction of 2-aminothiophenol with itaconic anhydride also gives the benzothiazepine system 155 <07JHC457> while dibenzothiazepines 157 were formed by denitrocyclisation of the sulfide 156 <07JHC1247>. 

Sulfuryl chloride and magnesium perchlorate have been suggested as acetylation catalysts for starch. Sulfur dioxide in acetic acid/ sulfur trioxide in acetic anhydride, and sulfonated fatty acid or sulfonated salicylic acid in a mixture of acetic anhydride and acetic acid have also been reported to acetylate starch. 

The reaction is acid or base catalyzed. Many catalysts have been tried, including potassium acetate and sodium acetate (27), dimeth-ylformamide (DMF) (28-30), urea ammonium sulfate (29), magnesium perchlorate (31-33), trifluoroacetic acid (32), boron trifluoride (30), sodium acetate (31), potassium hydrogen phosphate (34), and y-rays (35). The best acetylation condition, however, is uncatalyzed acetic anhydride in xylene at 100-130 C (36). 

A polymerisation variant is to use as catalyst oleum (a 30-60% solution of SOs in sulfuric acid), or better, in order to accelerate the reaction, a catalytic mixture of oleum-perchloric acid (or a perchlorate, such as magnesium perchlorate) [12,16,25,28]. Similar structures with sulfate ester units (structure 7.7) are obtained. By the hydrolysis of the resulting structure the desired PTHF with terminal hydroxyl groups is obtained [13, 25, 28]. 

An example can be given to illustrate the operation of the Perkin-EImer CHN analyser. A sample of about 3 mg was burned in oxygen, then a flow of helium took the products through a layer of catalysts to a mixer. The pressure in the mixer was maintained at 2 atm. A portion of gas was then directed from the mixer to the measuring part of the instrument, consisting of three thermal conductivity detectors and two absorbers. The first absorber contained magnesium perchlorate for absorption of water the second contained sodium hydroxide for absorption of carbon dioxide. 

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