Imide type salts

In order to develop more stable salts, imide type salts, LiCF3S03 and Li(CF3S02)2N decomposing at higher temperature than 400°C, have been synthesized [52]. These salts are suitable for rechargeable lithium batteries due to their high thermal stability. Unfortunately, these electrolyte salts cannot be used in practical batteries, because of A1 corrosion in nonaqueous electrolyte solutions with these electrolyte... 

Murase, K., Nitta, K., Hirato, T., Awakura, Y., Electrochemical behaviour of copper in trimethyl-n-hexylammonium bis((trifluoromethyl)sulfonyl)amide, an ammonium imide-type room temperature molten salt, /. Appl. Electrochem., 31, 1089, 2001. 

NHCs have novel chelating properties and have been shown to bind very strongly to a variety of metals to produce very stable complexes. In 1968 Ofele (J) and Wanzlick (2) used imid lium salt precursors to synthesize the fust transition metal N-heterocyclic carbene (NHC) con lexes of type 1. In 1982 Lappert synthesized several conq)lexes in which NHCs were bound to transition metals (i) and in 1991 Arduengo (4) reported the synthesis of a free isolable NHC. NHCs and their binding to transition metals are the subjects of several review articles (5, 6) and are of considerable interest in the field of catalysis. 

We have already discussed (p. 106) that T+ and T ionic forms can give the ester and amine products only. Thus, in acidic and neutral media which favor the formation of T+ and T1, imidate salts should always give the ester and amine products. In basic medium, which favors the formation of T , there is the possibility for the formation of both types of products, i, e., ester and amine or amide and alcohol. The cleavage of the C—N bond in the T" tetrahedral intermediate will take place only if the nitrogen electron pair can form a hydrogen bond with a solvent molecule. Thus, experimental evidence in favor of the principle of stereoelectronic control can be obtained with imidate salts, only when the hydrolysis is carried out under basic conditions. 

Similarly, mercury-nitrogen compounds may resemble either salts or acid-base type adducts. Saltlike compounds of this type include the familiar white amino compound, Cl—Hg—NH2, and analogous compounds formed from organic amines, for example, Cl—Hg—NHCH3 organic amides and imides also are known to form mercury derivatives, descriptions of which appear in more comprehensive works. 

The earliest method of this type was the old Marckwald synthesis (1] in which a suitable a-aminocarbonyl compound is cyclized with cyanate, thiocyanate or isothiocyanatc. More recent modifications have employed the acetals of the a-amino aldehyde or ketone or an a-amino acid ester. The two-carbon fragment can also be provided by cyanamide, a thioxamate, a carbodiimidc or an imidic ester. When cyanates, thiocyanates or isothiocyanates are used, the imidazolin-2-ones or -2-thiones (1) are formed initially, but they can be converted into 2-unsubstituted imidazoles quite readily by oxidative or dehydrogenative means (Scheme 4.1.1). The chief limitations of the method arc the difficulty of making some a-aminocarbonyls and the very limited range of 2 substituents which are possible in the eventual imidazole products. The method is nonetheless valuable and widely used, and typically condenses the hydrochloride of an a-amino aldehyde or ketone (or the acetals or ketals), or an a-amino-)6-ketoester with the salt of a cyanic or thiocyanic acid. Usually the aminocarbonyl hydrochloride is warmed in aqueous solution with one equivalent of sodium or potassium cyanate or thiocyanate. An alkyl or aryl isocyanate or isothiocyanate will give an A-substituted imidazole product (2), as will a substituted aminocarbonyl compound (Scheme 4.1.1) [2-4]. 

This shows that phthalimide is a compound of an anhydride type formed by loss of ammonia from phthalamide just as phthalic anhydride is formed from phthalic acid by the loss of water. Like other acid amides and imides phthalimide forms salts by replacement of the... 

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