Photoredox synthesis of Vicinal Dichloride using FeCl₃ as chlorine source

Abstract

This work presents a photo‐redox vicinal dichlorination of acrylamides using a naturally abundant chlorine source (FeCl3). The LMCT of FeCl3 is responsible for the chlorine radical inducement, while the tetra‐n‐butylammonium decatungstate (TBADT) catalytic system enhanced the process. This method exhibits extraordinarily mild conditions, not requiring external ligands and low E factors, which enables scalable synthesis.

Light‐Induced Vicinal Dichlorination of Alkenes Using FeCl3 as the Dichlorination Reagent

“…Combined with the pioneering works in literatures and our experiments above, [8–12] we proposed the possible photocatalytic mechanism mediated by FeCl 3 (Scheme 3). A possible pathway reported by Duan group etc involves light‐induced LMCT in FeCl 3 , [10,13a,17] which could promote the formation of free Cl ⋅ (route i).…”

“…A series of alkylethylenes were also tested as the substrates (Table 2, entries 11-19). As shown in Table 2 (entry 11), dichlorination of allylbenzene and 4-methoxyallylbenzene gave the target products in as high as 93 % and 91 % yields, respectively (Table 2,entries 11,12). Nallylphthalimides and butenyl benzoates were also smoothly coverted to the target products in 73-88 % yields.…”

“…In 2023, Tang and co-workers realized the dichlorination of olefins with FeCl 3 as chlorination reagent but the additional photocatalysts (e. g., TBADT, Scheme 1b) was essential. [12] Herein, our attention had been drawn to develop a concise method for vicinal dichlorination of alkenes under irradiation of the light by using FeCl 3 as the chlorination reagent (Scheme 1c) while no photocatalysts and HCl were required. The results provide a green and additive-free method of using inexpensive FeCl 3 as the chlorination reagent to enable vicinal dichlorination of alkenes.…”

“…In this context, LMCT process mediated by FeCl 3 under light provide an alternative strategy for selective dichlorination of alkenes. In 2023, Tang and co‐workers realized the dichlorination of olefins with FeCl 3 as chlorination reagent but the additional photocatalysts ( e. g ., TBADT, Scheme 1b) was essential [12] . Herein, our attention had been drawn to develop a concise method for vicinal dichlorination of alkenes under irradiation of the light by using FeCl 3 as the chlorination reagent (Scheme 1c) while no photocatalysts and HCl were required.…”

Selective poly(vinyl ether) upcycling via photooxidative degradation with visible light

“…29,30 We identified catalysts FeCl 3 and FeBr 3 due to their inexpensiveness, low level of toxicity, and ability to perform direct hydrogen atom transfer (HAT) under visible light. 31–33 After some initial optimization (see ESI†), we observed that PIBVE degradation in acetone at short reaction times (Fig. 1a, entries 1 & 2) was more efficient in the presence of FeBr 3 —in terms of number average molecular weight ( M n )—than in the presence of FeCl 3 .…”