Sulfur maleic acid hydrogenation

Initial Toxicities of Different Sulfur Compounds for Maleic Acid Hydrogenation... 

A solution of N-(2-aminobenzvl)-1-phenyl-2-metKylaminoethanol-1 was prepared by the reaction of a-bromo-acetophenone and (2-nitrobenzyl)methylamine, followed by hydrogenation of the nitro group by means of nickei on diatomaceous earth at room temperature and reduction of the CO group by means of sodium borohydride. The intermediate thus produced was dissolved in 100 ml of methylene chloride and introduced dropwise into 125 ml of sulfuric acid at 10° to 15°C. After a short standing, the reaction mixture was poured onto ice and rendered alkaline by means of a sodium hydroxide solution. Dy extraction with ether, there was obtained 1,2,3,4-tetrahydro-2-methyl-4-phenyl-8-amino-iso-quinoline. The base is reacted with maleic acid to give the maleate melting point of the maleate 199° to 201°C (from ethanol). 

The stereochemistry of cathodic hydrogenation is thus far not predictable or explainable. There is a preponderance for trans addition in the reduction of al-kynes, while cis addition occurs predominantly with cis- and trans-stilbene and maleic acid derivatives. On the other hand, dimethylmaleic acid and dimethyl-fumaric acid are exclusively hydrogenated to the trans products, meso- and dl-di-methylsuccinic acid 302 With a silver-palladium cathode in 5% aquous sulfuric acid triple bonds are reduced in a specific cis addition to double bonds 303 ... 

Liquid-phase hydrogenation of maleic acid (concentration 2.5x10 mol) on a platinum catalyst. Variation of relative rate of hydrogenation, rVA. with degree of coverage by sulfur. After Lamy Pitara et al. [1985]. 

The extraction of CNCs can be performed by strong acid hydrolysis of cellulose or purified cellulose under controlled conditions. Different common acids were used to extract CNCs such as sulfuric acid (H SO ), hydrochloric acid (HCl), and hydrobromic acid (HBr) whereas phosphoric acid (H PO ), maleic acid (HO CCHCHCO H), and hydrogen peroxide (H O) were used to a lesser extent. However, sulfuric acid is the most common acid used for acid hydrolysis of corresponding cellulose,where it reacts with hydroxyl (-OH) groups to form sulfate esters and produces stable aqueous suspension compromising thermal stabihty [6,8,59]. Apart from acid hydrolysis, many other processes have also recently been used to extract nanocrystalline cellulose from cellulose fibers such as enzymatic hydrolysis [60-62], TEMPO-mediated oxidation [63,64], hydrolysis with gaseous acid [65], and ionic liquid [66]. 

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