Photochemistry

Applications of Continuous-Flow Photochemistry in Organic Synthesis, Material Science, and Water Treatment

“…For example, the industrial synthesis of vitamin D 3 proceeds through a photochemical step. More specifically, the 9,10 double bond in provitamin D is cleaved via UV irradiation to yield the E and Z isomers of previtamin D . Moreover, since the installation of the first photochemical production unit in 1963, the synthesis of ε-caprolactam through the photonitrosation of cyclohexane (Toray process) has been an important step toward Nylon-6 .…”

“…More specifically, the 9,10 double bond in provitamin D is cleaved via UV irradiation to yield the E and Z isomers of previtamin D . Moreover, since the installation of the first photochemical production unit in 1963, the synthesis of ε-caprolactam through the photonitrosation of cyclohexane (Toray process) has been an important step toward Nylon-6 . The nitrosation of the alkane is based on the photoinduced cleavage of NOCl in the presence of HCl.…”

A Green Blue LED-Driven Two-Liquid-Phase One-Pot Procedure for the Synthesis of Estrogen-Related Quinol Prodrugs

“…Substrate scope of novel blue LED-driven two-liquid-phase photo-oxygenation a . The mechanism of dye-mediated photo-oxygenation of phenols has been reviewed and discussed; it includes the transfer of the excited state from the photosensitizer to the substrate (Type I mechanism), or alternatively the inter-crossing system between the photosensitizer and dioxygen, with formation of singlet oxygen ( 1 O2) (Type II mechanism) [38,[41][42][43]. Under our experimental conditions, the Type I mechanism was most probably not operating, as suggested by the loss of reactivity of the substrate in the absence of meso-TPP (Table 1, entry 5), associated with the low absorption coefficient of estrogens in the interaction with blue-LED photons (Figures S3-S6) [44][45][46][47].…”

“…The tentative reaction pathway for the photo-oxygenation of compounds 1a-d is reported in Scheme 2, it includes: (i) blue-LED photo-activation of meso-TPP to form the singlet excited state ( 1 meso-TPP*); (ii) intersystem crossing (ISC) to form the triplet excited state ( 3 meso-TPP*); (iii) energy transfer, and formation of singlet oxygen ( 1 O2); (iv) selective insertion of 1 O2 on substrate to yield an unstable adduct A (not isolated in our case); and (v) rearrangement of adduct A to yield the corresponding hydro-peroxide. The mechanism of dye-mediated photo-oxygenation of phenols has been reviewed and discussed; it includes the transfer of the excited state from the photosensitizer to the substrate (Type I mechanism), or alternatively the inter-crossing system between the photosensitizer and dioxygen, with formation of singlet oxygen ( 1 O2) (Type II mechanism) [38,[41][42][43]. Under our experimental conditions, the Type I mechanism was most probably not operating, as suggested by the loss of reactivity of the substrate in the absence of meso-TPP (Table 1, entry 5), associated with the low absorption coefficient of estrogens in the interaction with blue-LED photons (Figures S3-S6) [44][45][46][47].…”

Elasticity of Confined Simple Fluids from an Extended Peng-Robinson Equation of State

“…For a spherical pore shape and taking as a basis the PR EOS to describe the fluid’s properties in the bulk phase, for a simple and homogeneous fluid at a fixed temperature, the derived pressure equation and chemical potential are and which are approximate to PR EOS and its chemical potential when r p → ∞ . For the rest of the parameters and variables, μ 0 is the reference chemical potential, v is the confined molar volume, ρ = 1/ v is the molar density, P is the fluid’s pressure, T is its temperature, R is the gas constant, N A is the Avogadro number, b p = N A /ρ max , and a p = ah is the modified PR EOS parameters ( a and b ), h = N c, max /10, θ is a term that modulates the effect of the confined density on the fraction of molecules in the square-well region of the pore, F pr is the fraction of the confined molecules in the same square-well region for a random distribution of the fluid, N c, max is the average molecule–molecule coordination number in the packed structure, ρ max is the molecular density of the closed-packed fluid, and c 1 = 1.095, c 2 = 1.127, c 3 = 1.562, c 4 = 1.942, c 5 = 27.456, A = −4.68 × 10 –4 , B = 0.2628, U = 3.3445, M = −0.8141, ν = 3.25 × 10 –4 , η = 1.7948, and φ = 0.2666 are universal parameters for spherical pores obtained by fitting the packed density and eq with available data …”