Chromoselective Synthesis of Sulfonyl Chlorides and Sulfonamides with Potassium Poly(heptazine imide) Photocatalyst

Abstract

Among external stimuli used to promote a chemical reaction, photocatalysis possesses a unique one—light. Photons are traceless reagents that provide an exclusive opportunity to alter chemoselectivity of the photocatalytic reaction varying the color of incident light. This strategy may be implemented by using a sensitizer capable to activate a specific reaction pathway depending on the excitation light. Herein, we use potassium poly(heptazine imide) (K‐PHI), a type of carbon nitride, to generate selectively three different products from S‐arylthioacetates simply varying the excitation light and otherwise identical conditions. Namely, arylchlorides are produced under UV/purple, sulfonyl chlorides with blue/white, and diaryldisulfides at green to red light. A combination of the negatively charged polyanion, highly positive potential of the valence band, presence of intraband states, ability to sensitize singlet oxygen, and multi‐electron transfer is shown to enable this chromoselective conversion of thioacetates.

Red edge effect and chromoselective photocatalysis with amorphous covalent triazine-based frameworks

“…Potentials of the occupied states, VB or intraband states laying close to the VB, define the driving force for electron transfer from the substrate. Therefore, selective excitation of either n‒π* or π‒π* transitions in the conjugated polymers, such as carbon nitrides, can alter the selectivity of a chemical reaction 21 , 22 . Analyses of TCSPC data and steady-state emission spectra in combination with the results of CTFs photocatalytic activity in oxidative bromination and dual Ni-photocatalytic C-N cross-coupling suggest that the concept is applicable for our systems as well.…”

“…In their approach, illumination of a photocatalytic system composed of Rhodamine 6 G, a homogeneous sensitizer, and electron donor with green or blue photons gives either moderately (‒1 V) or highly reductive (‒2.4 V vs SCE) species, respectively. In semiconductor carbon nitride photocatalysis, Kroutil et al 21 and our group 22 achieved various oxidation potentials of the excited state by selective excitation of n‒π* or π‒π* transitions. Overall, in chromoselective catalysis, one specific reaction pathway (out of multiple possible) is enabled by the photon of specific wavelength 23 – 25 .…”

Progress in Development of Photocatalytic Processes for Synthesis of Fuels and Organic Compounds under Outdoor Solar Light

“… 79 Oxidation of heteroatoms is possible as well; a recent publication proved the conversion of protected thiophenols to other valuable sulfur-containing molecules (in the case of solar irradiation, sulfonyl chlorides) by a poly(heptazine imide) carbon nitride catalyst; again, implementation of sunlight allowed shortening the reaction time 4-fold compared to a 50W 465 nm LED. 80 …”

Light as a Tool in Organic Photocatalysis: Multi‐Photon Excitation and Chromoselective Reactions

“…[49] These three possibilities were investigated in the reaction of thiophenol (or acetothiophenol) oxidation under different excitation lights (Figure 11). [50] To study the chromoselectivity effect this reaction was carried out under the variety of wavelength: UV (365 nm), purple (410 nm), blue (465 nm), white (410-800 nm), green (525 nm), and red (625 nm) (Figure 11b). Three different products were obtained from the single reaction mixture depending on the light color.…”