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• 941-55-9 4-toluenesulfonyl azide 

Relevant academic research and scientific papers

Spectroscopy and kinetics of triplet 4-methylbenzenesulfonylnitrene

Triplet 4-methylbenzenesulfonylnitrene 3 was studied by solution phase laser flash photolysis, low-temperature absorption spectroscopy, and low-temperature EPR spectroscopy. Upon laser flash photolysis of 4-methyl-benzenesulfonyl azide 1 in ethanol, absorption maxima were observed at 325 and 460 nm while in cyclohexane, a single maximum was observed at 310 nm. The short-wavelength absorptions were assigned to the triplet nitrene. There was no evidence that hydroxylic solvents catalyzed intersystem crossing from the singlet to the triplet state of 3. After irradiation of 1 in an EPA glass at 77 K, a band at 313 nm was observed. The zero-field splitting parameters from the EPR spectrum of the nitrene in an EPA glass at 77 K were |D/hc| = 1.471 cm-1 and |E/hc| = 0 cm-1. Remarkably, 3 was not stable at 77 K in EPA. Irradiation of 1 also produced a second nitrene species, possibly (4-methylphenyl)nitrene, with D/hc| = 0.9840 cm-1 and |E/hc| = 0 cm-1. The decay of the 325 nm transient was first order in ethanol (τ = 8.96 ± 0.48 μs), methanol (τ = 8.18 ± 0.08 μs), and methanol-d4 (τ = 8.02 ± 1.76 μs).

Exploring photochemistry of p-bromophenylsulfonyl, p-tolylsulfonyl and methylsulfonyl azides by ultrafast UV-pump-IR-probe spectroscopy and computations

The photochemistry of p-bromophenylsulfonyl azide (BsN3), p-tolylsulfonyl azide (TsN3) and methylsulfonyl azide (MsN3) was studied by femtosecond time-resolved infrared spectroscopy with CH2Cl2 and CCl4 as solvents along with quantum chemical calculations. The photolysis of these azides after 267 nm light excitation leads to the population of each respective azide S1 excited state. Decay of the S1 excited state gives rise to singlet nitrene formation. In the case of BsN3, the decay was found to correlate with the formation of a pseudo-Curtius photoproduct (PCP) BrC6H4NSO2. Transient electronic ground states of the three azides on their way to singlet nitrenes and PCPs were shown by locating the corresponding transition states on the potential energy surfaces. The lifetime of singlet 1(BsN) and 1(TsN) nitrenes is τS = ～20 ps in CH2Cl2 and ～700 ps in CCl4. Singlet 1(MsN) was not detected. Due to fast intersystem crossing (ISC), singlet nitrenes are converted into the triplet spin isomers lying lower in energy, the formation time constants being equal to the corresponding singlet nitrene lifetime. The formation of 3(MsN) was shown and the formation time constant in CH2Cl2 was found to be τISC = 34 ± 3 ps. Internal conversion of the S1 excited state to the ground state of the azide was low (Φ ≈ 0.15) for BsN3 and TsN3 and was not found in the case of MsN3.