Acidic hydrogens, resistance

In most respects, copper-nickel and copper-tin alloys behave similarly to copper-zinc alloys. The presence of acids, hydrogen sulfide, ammonia, and carbon dioxide degrades corrosion resistance. 

In recent years some additional data on the corrosion resistance of the Ni-Fe alloys has been generated, but it is fairly limited and the foregoing material summarises the majority of the available information. The additional data falls into the categories, electrochemical, resistance to acids and resistance to hydrogen cracking. 

Merocyanine Dye Method for Acid Analysis. Resist photochemistry can often be monitored by the changes in ultraviolet absorption spectra associated with a bleaching of the sensitizer absorbance. In the case of resist systems with triphenylsulfonium salts, no change in the film absorption is observed on irradiation. In order to determine the amount of acid produced, a direct method for acid analysis was required. A highly sensitive method was desirable since the amount of acid produced is approximately 10 6 mmol for a 1 micrometer thick film on a 2 inch wafer. Furthermore a nonaqueous technique is preferred in order to avoid hydrolysis of the hexafiuoroantimonate salt. Hydrolysis gives hydrogen fluoride (14) which makes accurate acid determination more difficult. 

The route for the cytotoxic ipomoeassin resin glycosides relied on the use of compound 256 as a new cinnamic acid surrogate with its trisubstituted double bond and meets the requirement of being hydrogenation resistant in the presence... 

Esters of carboxylic acids are resistant toward sulfur tetrafluoride up to 300 °C. However, in the presence of an excess of hydrogen fluoride, they react like the acids to give trifluoromethyl compounds [187,235] In contrast, esters of highly fluorinated acids or alcohols react with sulfur tetrafluonde in a hydrogen fluoride solution under mild conditions without cleavage of the ester bond and give products of the replacement of carbonyl oxygen by fluorine a,a-difluoroethers [235, 236, 237, 238] (equations 124 and 125). 

Like the parent compounds, the methyl ethers of aldobiouronic acids are resistant to acid hydrolysis, and it is difficult to carry out hydrolysis without some decomposition of the product. This difficulty has recently been overcome by reduction of the uronic acid residue with lithium aluminum hydride66-67 the resulting disaccharide then undergoes hydrolysis without difficulty. The first reduction of the uronic acid residue of a methylated aldobiouronic acid methyl ester was accomplished by Levene, Meyer and Kuna,69 who reduced the methylated aldobiouronic acid from gum arabic with hydrogen in the presence of copper chromite catalyst under the conditions previously used701 for reducing the acety-... 

INCO Corrosion Engineering Bulletin CEB-5. Corrosion Resistance of Nickel-Containing Alloys in Hydrofluoric Acid, Hydrogen Fluoride and Fluorine." New York, NY International Nickel Company, 1968. 

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