Cyano absorptions

When methylene chloride solutions of the alkene and aluminium trichloride were mixed a yellow solid precipitated. The precipitate contained both alkene and aluminium trichloride. Except for the cyano absorption the IR spectrum of the alkene in the precipitate is unchanged. Aluminium trichloride has co-ordinated to the cyano groups but not broken the double bond - a betaine has not been formed. The complex appears to be polymeric, it will not dissolve in polar aprotic solvents. However, it will dissolve in chloroform without chemical reaction if a little methanol is added. Apparently, the polymeric structure is disrupted by methanol co-ordination. The HNMR (in CDC13) spectrum shows that one molecule of alkene dissolves per molecule of alcohol. Despite the proximity of an alcohol molecule to the strongly polarized alkene no chemical reaction takes place in this solvent. 

Furthermore, a direct identification of defined resin-bound molecules is possible through superpositioning of the IR maps. If, for example, the maps of the imide (1730 cm - ), nitro (1360 cm 1), and cyano absorptions (2225 cm1) are placed on top of each other, the resin beads that carry exclusively compound 1 can be identified with spatial resolution in the overlapping regions (Fig. 16.17, stars) of the functional groups. The FT-IR spectra of the individual resin beads extracted from the maps clearly confirm attachment of 1 to the resin bead (Fig. 16.18). 

Figure 16.17. FT-IR tagging by superpositioning of the 1R maps of imide (1730 cm - ). nitro (1360 cm ), and cyano absorptions (2225 cm-1). Resin beads on which compound 1 is immobilized were identified through overlapping regions of all IR maps.

The IR indicates that the trans, trans-disat absorption band at 985 cm is renioved while the 970 cm shoulder for cis, trans-diene group is unchanged. The cyano absorption appears weakly at 2220 cm. ... 

As a class of compounds, the two main toxicity concerns for nitriles are acute lethality and osteolathyrsm. A comprehensive review of the toxicity of nitriles, including detailed discussion of biochemical mechanisms of toxicity and stmcture-activity relationships, is available (12). Nitriles vary broadly in their abiUty to cause acute lethaUty and subde differences in stmcture can greatly affect toxic potency. The biochemical basis of their acute toxicity is related to their metaboHsm in the body. Following exposure and absorption, nitriles are metabolized by cytochrome p450 enzymes in the Hver. The metaboHsm involves initial hydrogen abstraction resulting in the formation of a carbon radical, followed by hydroxylation of the carbon radical. MetaboHsm at the carbon atom adjacent (alpha) to the cyano group would yield a cyanohydrin metaboHte, which decomposes readily in the body to produce cyanide. Hydroxylation at other carbon positions in the nitrile does not result in cyanide release. 

To the aqueous suspension of the palladized charcoal catalyst thus obtained are added 20.8 kg of 3-cyano-pyridine (96% purity) and then are added 70 liters of a hydrochloric acid solution prepared by diluting 30 liters of 36% HCI with 40 liters of water. This represents approximately 1.75 mols of HCI for each mol of 3-cyano-pyridine. The suspension is maintained at 10° to 15°C and stirred continuously while introducing a current of hydrogen at a pressure of 3 to 5 psi. When absorption of hydrogen ceases and the 3-cyano-pyridine is completely reduced, the reaction mixture is filtered to remove the catalyst. 

Absorption spectra of formazans have been studied in detail. Almost all formazans exhibit UV/visible spectra between 300 and 600 nm.1,2,12,13,40,62,325 326 The absorption maxima are very sensitive to substituent effects. For example, the 1,5-diphenyl formazan 185 when X is hydrogen, methyl, phenyl, cyano, and mercapto shows a band at 420, 410, 470, 504, and 590nm in ethanol, respectively. The 3-chloro derivative 186 when X is hydrogen, iodine, bromine, chlorine, and fluorine has a band at 433,433,430,421, and 417 nm, respectively. Table 13 shows the influence of substituents on the absorption maxima in the trisubstituted formazans 3. Table 14 shows the influence of substituents on the absorption maxima of... 

The IR spectrum which can be measured in argon at 10 K after irradiation of diazo compound 18 with k = 313 nm is relatively complex. But the absorptions of 19 can be extracted by a subsequent irradiation with k > 570 nm. The signals of 19 decrease in intensity during this secondary irradiation. They fit much better with the bands calculated for T-19 than for S-19. The product formed under these conditions (X > 570 nm) is the ring-opened carbene 16, which in this case can directly be detected and shows an IR spectrum which is in agreement with that of S-16. Intermediate 16 can be transferred photochemically to 2-cyano-2/7-azirene (17) with X > 313 nm, which is the main product in the primary irradiation of diazocompound 18 with this wavelength. 

In order, the two complex ions are [Fe( H20)6]1 2 3 and [Fe(CN)6]. We know that CN is a strong field ligand it should give rise to a large value of A0 and result in the absorption of light of the shorter wavelength. We would expect the cyano complex to absorb blue or violet light and thus K4[Fe(CN)6]-3 H20 should appear yellow. The compound... 

Matrix isolation photolytic studies on tetrazolo[l,5- ]pyridazine 25 have been reported by Hill and Platz <2003PCP1051> (Scheme 5) and formation of the l-cyano-3-diazopropene 27, triazacycloheptatetraene 28, and cyano-cyclopropene 29 was detected. Upon the absence of electron spin resonance absorptions at 7 K, the authors concluded that triplet nitrene was not formed but, instead, the resulting singlet nitrene rapidly underwent further ring openings. 

Rettig and Gleiter81 have studied the dependence of intramolecular rotation in 4-cyano-IVTV-dialkylanilines 6-12 on the twist angle by fluorescence, UV absorption and PE spectroscopic measurements. The twist angles were determined from the split of the first and the third IP. While in molecules 6, 8 and 9, 11 and 12 the twist of the amino group... 

W. Rettig and R. Gleiter, Dependence of intramolecular rotation in p-cyano-N,N-dialkylanilines on the twist angle. A fluorescence, UV absorption, and photoelectron spectroscopic study. J. Phys. Chem. 89,4676(1985). 

Kinetics. The reaction of N-dodecyl 3-carbamoyl pyridinium bromide (I) with cyanide ion in the microemulsions was observed by following the 340 nm absorption maximum of the 4-cyano adduct (II). See equation (1). Following the work of Bunton, Romsted and Thamavit in micelles ( ), a 5/1 mole ratio of KCN to NaOH was employed to prevent cyanide hydrolysis. The pH of each reaction mixture was measured on a Coleman 38A Extended Range pH meter to insure that the system was sufficiently basic to allow essentially complete ionization of the cyanide. The appropriate amounts of cyanide and hydroxide were added to the mlcroemulslon sample within 10 minutes of running a reaction. Cyanide concentration varied between 0.02 and 0.08 M with respect to the water content. Substrate was Injected via a Unimetrics model 1050 syringe directly into a known volume of the yE-nucleophlle mixture in a 1.0 cm UV quartz cell. Absorbance at 340 nm was followed as a function of time on a Perkln-Elmer model 320 spectrophotometer at 25.0 + 0.3 C. Since the Initial bulk concentration of substrate was 10 M, cvanide was always present in considerable excess. 

With DFT calculations, identification of A as the bisnitrene 13 was rather easy because 13 is the expected product and an excellent match between theoretical predictions and experimental IR data was found. Identification of the secondary photoproduct (B) was more challenging, because a pathway leading to it is not immediately obvious. The presence of a weak absorption of B at 2210 cm hinted at the possible presence of a cyano group, which was helpful in considering possible structures. However, it was the ease of carrying out the calculations that made possible the efficient screening of several candidate structures for B. Component B was identified as the substituted cyclopropene 14 (Scheme 2), and. 

Tetracyano ligands have been used to bridge between four Ru(NH3)5 moieties. The complexes [ Ru(NH3)5 4(/i-L)] + (L = tetracyanoethene, tetracyano-p-quinodimethane, 1,2,4,5-tetracyano-benzene, 2,3,5,6-tetracyanopyrazine) exhibit intense, long-wavelength electronic absorptions. Oxidation to [ Ru(NH3)5 4(yU-L)] °" " and reduction to [ Ru(NH3)5 4(//-L)] + and [ Ru(NH3)5 4-(/i-L)] + can readily be achieved. The species are fully delocalized with partially reduced ligands or partially oxidized Ru centers. Treatment of [5,10,15,20-tetrakis(4-cyanophenyl)porphyrinato] cobalt(II) or [5,10,15,20-tetrakis(4-cyano-2,6,-dimethylphenyl)porphyrinato]cobalt(II) with [Ru-(NH3)5(0S02CF3)] introduces cyano-bound pendant Ru (NH3)5 groups to the porphyrinato complexes. ... 

A number of cyano-bridged complexes are included here even though they strictly do not fall in the general family-type defined for the section. The syntheses and photophysical properties of [(NC)(bpy)2Ru(/r-NC)Cr(CN)5] and [(NC)5Cr(Ai-CI Ru(bpy)2(M-NC)Cr(CN)5] have been described. Absorption of visible light by the Ru(bpy)2 unit results in phosphorescence from the Cr(CN)g luminophore, and the results evidence fast intramolecular exchange energy transfer from the MLCT state of the Ru(bpy)2 chromophore to the doublet state of the Cr -based unit. Time-resolved resonance Raman and transient UV-vis absorption spectroscopies have been employed to investigate the MLCT excited states of [(NC)(bpy)2Ru(//-CN)Ru (bpy)2(CN)], [(NC)(bpy)2Ru(//-CN)Ru(phen)2(CN)]+, [(NC)(phen)2Ru(//-CN)Ru (bpy)2(CN)]+, [(NC)(bpy)2... 

Absorption spectra for mesoionic 3-phenyl-1,2,3,4-thiatriazolium-5-cyano(ethoxycarbonyl) methylide, 5-di(ethoxycarbonyl) methylide, 5-/ -toluenesulphonamidate, and 5-(Y-methylanilino) iodide have been reported <93MRC447>. See also Section 4.19.2.3. 

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