Direct liquid-phase phenol-to-aniline amination using Pd/C

Abstract

Here, we report the first direct amination of phenol with ammonia into primary anilines in the liquid phase using Pd/C.

Direct conversion of phenols into primary anilines with hydrazine catalyzed by palladium

“…Recently, a liquid phase phenol to aniline transformation was reported, but still requiring high temperature (200 °C) and large excess amounts of ammonia gas and hydrogen gas with a very limited substrate scope (phenol and o / m / p -cresols); and at relatively lower temperature, this transformation suffered from both low conversion of phenol and poor selectivity towards the primary aniline, which can be attributed to the weak nucleophilicity of ammonia and the low stability of the cyclohexylimine intermediate. Such an intermediate is prone to undergo a reduction process to form cyclohexylamine under reductive conditions 9. Therefore, a general and relatively mild phenol to primary aniline transformation is yet to be developed.…”

Synthesis of Functional Chemicals from Lignin‐derived Monomers by Selective Organic Transformations

“…[6b,14] The cross-coupling of phenols with ammonia or other À NH 2 source can also provide direct access to anilines. [22,23,24] Aminolysis is one of the industrially important amination reactions applied for the production of aniline from phenol and gaseous ammonia in presence of Lewis acidic catalysts such as SiO 2 À Al 2 O 3 , TiO 2 À Al 2 O 3 , H 3 PO 4 , ZrO 2 À Al 2 O 3 , or WO 3 . [22] In general, this reaction is conducted in gas-phase at high temperatures (350-500°C).…”

“…[22] In general, this reaction is conducted in gas-phase at high temperatures (350-500°C). Interestingly, the group of De Vos [23] described the amination of different phenols using ammonia and molecular hydrogen in presence of Pd-based heterogeneous catalysts. Various heterogeneous catalysts were screened and found that Pd/C exhibited superior activity, producing up to 92% of aniline from phenol at 200°C with 4 bar NH 3 and 1 bar H 2 (Scheme 1).…”

Dearomatization–Rearomatization Strategy for Palladium-Catalyzed C–N Cross-Coupling Reactions

“…Due to the importance of non-N-substituted anilines, in 2018 Dirk E. De Vos and coworkers achieved the conversion by using NH 3 as nitrogen source and H 2 as reducing agent. 13 Primary anilines were generated from phenols with good selectivity and moderate to high yields in the liquid phase. However, only four examples were shown in their research, and the ortho-substituted group (methyl group) was sensitive to this transformation, giving both moderate yield and conversion.…”