4- Nitrosalicylaldehyde

The 5-nitrosallcylaldehyde reagent is prepared as follows. Add 0-5 g. of 5-nitrosalicylaldehyde (m.p. 124-125°) to 15 ml. of pure triethanolamine and 25 ml. of water shake until dissolved. Then introduce 0-5 g. of crystallised nickel chloride dissolved in a few ml. of water, and dilute to 100 ml. with water. If the triethanolamine contains some ethanolamine (thus causing a precipitate), it may be necessary to add a further 0 - 5 g. of the aldehyde and to filter off the resulting precipitate. The reagent is stable for long periods. 

For the optically active Schiff bases [24], [25] in CDCI3, the 815N values were in the range from —65.2 to 230.3 ppm and increased for the following series of derivatives salicylaldehyde < 3-bromosalicylalde-hyde < 5-nitrosalicylaldehyde < 4,6-dimethoxy-salicylaldehyde < 2-hydroxynaphthaldehyde which resulted from increased mole fraction of the NH-form.12... 

The catalytic activity varies with the anion of the cuprous salt. Thus the activities of the acetate, salicylaldehyde, and 4-hydroxysalicylaldehyde are similar and somewhat higher than those of the stearate and benzoate. Cuprous nitrobenzoates and nitrosalicylaldehydes, as well as the cuprous complexes of certain Schiff bases, are inactive. The general trend appears to be for the catalytic activity to increase with the basicity of the anion. This has been interpreted in terms of a decrease in the energy required to promote electrons from the full 3d shell to empty upper orbitals (Calvin and Wil-marth, 32). 

Nitrosalicylaldehyde reagent test. This test is based upon the fact that 5-nitro-salicylaldehyde and nickel ions when added to a primary amine produce an immediate precipitate of the nickel derivative of the Schiffs base. 

A more subtle case involves the bromonitrosalicylaldehydes. Bromination of 3-and 5-nitrosalicylaldehydes gives the expected 5-bromo-3-nitro- (62% yield) and 3-bromo-5-nitrosalicylaldehyde (56%), respectively. In the alternative route to these compounds, nitration of 3-bromosalicylaldehyde gives the expected 3-bromo-5-nitro... 

The condensation of 2,3,3-trimethylinolenine with aryl aldehydes gave the corresponding 2-styrylindolenines. Condensation with 5-nitrosalicylaldehyde and its 3-bromo, 3-methoxy, and 3-nitro derivatives similarly gave the 2-(2-hydroxy-styryl)indolenines (46, 73, 68 and 91% yields, respectively), rather than the corresponding merocyanine or spiropyran forms. These indolenines were neither photochromic nor solvatochromic.53... 

Not all heterocyclic methylene bases give spiropyrans (at least under the usual conditions). l,3,4,5,5-Pentamethyl-2-methylene-2,5-dihydropyrrole (69)77 did not condense with 5-nitrosalicylaldehyde to give any photochromic material.7 However, l-methyl-2-methylene-3,3,4,5-tetraphenyl-2,3-dihydropyrrole (70), prepared by reaction of methyllithium with 1 -methyl-3,3,4,5-tetraphenylcrotonolactam, did condense with 5-nitrosalicylaldehyde to give a product exhibiting reverse photo-chromism the unexposed form was red and the exposed form yellow. This behavior probably represents a trans to cis isomerization of the open form 7... 

AminoFischer s base was condensed with the diacid chlorides of glutaric, pimelic, and azelaic acids to give in 70-92% yields the bis-amides, which upon reaction with 5-nitrosalicylaldehyde gave 70-88% of the bis-spiropyrans (72, n = 3,5,7). The alternative route, reaction of the acid chlorides with 5 -amino-6-nitroBIPS, is impractical because of the difficulty of obtaining this BIPS. The bis-BIPS exhibit strong photochromism. The open forms precipitate in nonpolar... 

In attempts to prepare 3-acyl-substituted BIPS (113), various salicylaldehydes were condensed with l,3,3-trimethyl-2-formylmethyleneindoline (Fischer s aldehyde). In alcohol, dimethylformamide, tetrahydrofuran, Y-mcthylpyrrolidonc. and hexamethylphosphoramide as the sole solvents, decarbonylation occurred and the only products were the BIPS compounds. However, in dimethyl sulfoxide, 5-nitro-and 3-bromo-5-nitrosalicylaldehydes gave 11 and 5.6% of the desired 3-formyl-BIPS, respectively. The structures were assigned from their IR and NMR spectra. 

Thus, the condensation of 2-phenyl-l,3,6-trimethyl-2-azaazulenium perchlorate with 5-nitrosalicylaldehyde gave the cationic styryl dye (A,max 510 nm) in 56% yield.139 This dye is the salt of the open form of the corresponding spiropyran, and upon treatment with base, a reaction which was not originally reported, was found to give the expected dye (126), which absorbs at 733 and 536 nm. This material did not thermally fade or photobleach to any significant extent with visible light in either polar or nonpolar solvents.7... 

Note 6. This is the proton-transfer reaction that gives the (orange-colored) anion of the nitrosalicylaldehyde (and the colorless indoleninium cation). 

D. A. Drapkina, An error in the structures assigned to 6 -bromo-8 -nitro-3,3 -dimethylspiro[ben-zothiazoline-2,2 -(2 //-1-benzopyran] and 5-bromo-3-nitrosalicylaldehyde, J. Org. Chem. USSR, 7, 2083 (1971). 

Nitrosalicylaldehyde can be isolated after diazotization of anthranil, followed by heating.268... 

Acetoxymercuri - 3 - nitrosalicylaldehyde.—Four grams of aldehyde and 7 grams of mercuric acetate w4ien treated as above give 9 grams of the compound. It is insoluble in organic solvents and does not melt at 260° C. 

Nitrophenols, irradiation of 1073 5-Nitrophenols, synthesis of 639 2-Nitroresordnol, IR LD spectrum of 384, 385 5-Nitrosalicylaldehyde, NMR spectra of 336 Nitrosation 606... 

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