Formation Of Nitrile Ylide Research Articles

ChemInform Abstract: Photochemistry of 2H-Azirine - Formation of Nitrile Ylide Evidenced by Laser Flash Photolysis and Pulse Radiolysis.

Laser flash photolysis of 3-(4-biphenylyl)-2H-azirine (AZ) was carried out in cyclohexane for the direct detection of a nitrile ylide (NY). Two kinds of transient species, triplet AZ (T1) and NY, have been measured. Decay rates of these species were determined to be 6.7×105 s−1 (T1) and 8×10 s−1 (NY). The rate constants for the reactions of NY toward acetone and acrylonitrile were determined to be 2.5×103 dm3 mol−1 s−1 and 2.3×106 dm3 mol−1 s−1, respectively. These results were supported by the results of pulse radiolysis of AZ in benzene and stational irradiations of AZ.

Formation of Nitrile Ylide by Addition of Carbene with Acetonitrile in a Low-Temperature Argon Matrix

Formation of Nitrile Ylide by Addition of Carbene with Acetonitrile in a Low-Temperature Argon Matrix

Formation of Nitrile Ylide by Addition of Carbene with Acetonitrile in a Low-Temperature Argon Matrix

After the photoirradiation of (biphenyl-4-yl)chlorodiazirine (BCD) in ca. 10 K argon (Ar) matrices, the IR spectrum of (biphenyl-4-yl)chlorocarbene (BCC) was measured because the measured bands were in fair agreement with the bands obtained by vibration analysis. The photolyses of BCD−acetonitrile (MeCN)−Ar tricomponent matrices were also carried out to study the reaction of BCC with MeCN. For [MeCN]/ [BCD] > 10, a spectrum that differed from BCC was obtained after the irradiation. The new bands are stable during the irradiation, during increasing temperature (to 45 K), and during storage. An 2-azonia-1-allenide type nitrile ylide (NY) structure was obtained in an optimization. Because the measured bands are in good agreement with those calculated using the vibration analysis for this NY structure, BCC adducts with MeCN immediately after the degradation of BCD.

Formation of nitrile ylides in the addition of singlet carbene to nitrile compounds—laser flash photolysis of (biphenyl-4-yl)chlorodiazirine in the presence of nitrile compounds

Formation of a nitrile ylide (NY) by addition of a singlet carbene to a nitrile compound was studied by laser flash photolysis (LFP) of (biphenyl-4-yl)chlorodiazirine (BCD) in the presence of nitrile compounds. Although the generated (biphenyl-4-yl)chlorocarbene (BCC) forms a NY by addition to a nitrile compound in an equilibrium reaction, the absorption spectrum of the NY can be measured only in the LFP of BCD in the presence of 2,4,6-trimethoxybenzonitrile. The equilibrium constants for the NY formation in the addition of BCC to propiononitrile or pivalonitrile were determined to be 0.45 and 0.37 M–1 at 295 K, respectively. The reactivity of NY towards olefins seems to be substantially lower than those of BCC. The reaction of BCC with 2,3-dimethylbut-2-ene was carried out in 2,2,4-trimethylpentane and propionitrile in the temperature range of ca. 170 to 300 K. In both solvents, the rate constants increased with decreasing temperature and the maximum value appeared at around 210 K. Using the difference in the rate constants, the free energy difference for the equilibrium constant was also estimated to be ca. 4.2 kJ mol–1.

Laser flash photolysis studied of 1-naphthyldiazomethane. Formation of nitrile ylides

Laser flash photolysis of the title compound or the corresponding diazirine produces 1-naphthylcarbene, which readily reacts with nitriles (e.g. for acetonitrile kr = 4.6 × 105 M−1 s−1) to yield nitrile ylides that absorb strongly at 390 nm.