It is attractive but challenge to develop non-noble metal-based photocatalytic system for selective oxidation of benzyl alcohol to benzaldehyde under solvent-free conditions. Herein, a Z-scheme heterojunction photocatalyst of ZnO/C3N4 was...
The furanic diether of 2,5-bis(isopropoxymethyl)furan (BPMF) derived from 5-hydroxymethylfurfural (HMF) can be used as a biobased fuel or fuel additive. It is highly desirable but challenging to develop a one-pot process for the transformation of HMF into BPMF because it is a cascade sequence reaction involving reduction and etherification reactions over multifunctional acid catalysts. In this work, zirconium-based catalysts were facilely prepared from a zirconium salt, sulfosalicylic acid, and biomass by a simple hydrothermal method. The obtained catalyst with both Brønsted and Lewis acids (BA and LA, respectively) can transform HMF into BPMF with a yield of 92.4% in 2propanol by Meerwein−Ponndorf−Verley reduction and etherification in a one-pot strategy. Additionally, the reaction pathway and mechanism of the reductive etherification reaction was investigated and is presented. This work proposes an approach for the preparation of a solid acid catalyst with multifunctional BA and LA for reductive etherification of aldehydes to ethers.
Highly direct oxidative cyanation of alcohols provides
a promising
synthesis route for the cyanide-free synthesis of organic nitriles.
It is challenging to explore a noble metal-free catalyst for direct
conversion of alcohol to nitrile under ammonia conditions because
it is a three-step consecutive reaction. In the present work, the
CoO
x
/MnO2 catalyst was developed
for direct oxidative cyanation of benzyl alcohol to benzonitrile with
a yield of 86% and a selectivity of 91% with aqueous ammonia. The
selectivity to benzonitrile and benzamide can be tuned via water accelerating
the transformation of benzonitrile to benzamide. In addition, the
kinetic studies reveal that the first step of the oxidation of benzyl
alcohol is the rate-determining step for the consecutive reactions.
It is found that Mn species are the main active sites while Co species
are the co-catalyst for the titled reaction. Moreover, the starting
substrates employed in the present catalytic system can be expanded
to aliphatic, benzylic, allylic, and heterocyclic alcohols, which
demonstrates a sustainable strategy for the direct synthesis of nitrile
from alcohol while avoiding the use of the conventional toxic cyanide.
Quinone-amine polymers can be employed as a metal-free and reductant-free catalyst for the hydroxylation of benzene to phenol and can yield phenol as high as the transition metal catalyst.
A catalyst-free method for the hydroxylation of arylboronic acids to form the corresponding phenols with sodium perborate as the oxidant was developed using water as the solvent or solvent free condition.
Ammoxidation of alcohols is a promising cyanidefree strategy for the synthesis of organic nitriles. It is desirable but challenging to conduct nitrile synthesis over a heterogeneous metal-free catalyst with aqueous ammonia as a nitrogen source and molecular oxygen as an oxidant. In the present work, an Se,P,Ntridoped carbon nanomaterial (Se,P,N/CN-900) was prepared and used as a metal-free catalyst for the direct ammoxidation of alcohols to nitriles with aqueous ammonia and molecular oxygen. The synergistic effect was revealed for the highly efficient catalytic performance of the tridoped carbon catalyst. The present catalyst showed good stability, and various (hetero)aromatic alcohols can be converted to the corresponding nitriles with high yields. To the best of our knowledge, this is the first work to achieve ammoxidation of alcohols to nitriles with a high efficiency over multidoped carbon materials.
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