Improved photocatalytic performance for selective oxidation of amines to imines on graphitic carbon nitride/bismuth tungstate heterojunctions.

Title Improved photocatalytic performance for selective oxidation of amines to imines on graphitic carbon nitride/bismuth tungstate heterojunctions.
Authors A. Yuan; H. Lei; Z. Wang; X. Dong
Journal J Colloid Interface Sci
DOI 10.1016/j.jcis.2019.10.060
Abstract

Imine compounds are vital intermediates in organic synthesis, and their cost-effective and green preparation has inspired numerous interests. Herein, we employ an environmentally friendly photocatalysis strategy to selectively oxidize amines to obtain imines. The heterojunction photocatalysts of graphitic carbon nitride/bismuth tungstate (CN/BW) were fabricated by hydrothermal growth of bismuth tungstate on the surface of graphitic carbon nitride. Characterization results demonstrate that the composites have been well composited and show improved separation ability of photo-generated charge carriers due to the formed type II band alignment. In comparison to the individual CN and BW, the heterojunctions exhibit apparent enhanced activity for the selective oxidation of amines to imines using O as the oxidant under irradiation of visible light. The optimized CN/BW heterojuntion with 75% BW content presents the high conversion (~98%) and selectivity (~98%) in 3?h oxidative coupling reaction of benzylamine. Furthermore, this heterojunction photocatalyst also has excellent cycling stability, as well as good catalytic performance for various benzylamine derivatives. On the basis of experimental results, the transfer pathway of photo-excited electrons and holes in the heterojunction photocatalyst was illustrated and a possible mechanism for the subsequent selective oxidation of amines to imines was proposed. This work provides an economical, sustainable and thus green process for the amine transformation.

Citation A. Yuan; H. Lei; Z. Wang; X. Dong.Improved photocatalytic performance for selective oxidation of amines to imines on graphitic carbon nitride/bismuth tungstate heterojunctions.. J Colloid Interface Sci. 2020;560:4049. doi:10.1016/j.jcis.2019.10.060

Related Elements

Bismuth

See more Bismuth products. Bismuth (atomic symbol: Bi, atomic number: 83) is a Block P, Group 15, Period 6 element with an atomic radius of 208.98040. The number of electrons in each of Bismuth's shells is 2, 8, 18, 32, 18, 5 and its electron configuration is [Xe] 4f14 5d10 6s2 6p3. Bismuth Bohr ModelThe bismuth atom has a radius of 156 pm and a Van der Waals radius of 207 pm. In its elemental form, bismuth is a silvery white brittle metal. Bismuth is the most diamagnetic of all metals and, with the exception of mercury, its thermal conductivity is lower than any other metal. Elemental BismuthBismuth has a high electrical resistance, and has the highest Hall Effect of any metal (i.e., greatest increase in electrical resistance when placed in a magnetic field). Bismuth is found in bismuthinite and bismite. It is also produced as a byproduct of lead, copper, tin, molybdenum and tungsten extraction. Bismuth was first discovered by Early Man. The name Bismuth originates from the German word 'wissmuth,' meaning white mass.

Carbon

See more Carbon products. Carbon (atomic symbol: C, atomic number: 6) is a Block P, Group 14, Period 2 element. Carbon Bohr ModelThe number of electrons in each of Carbon's shells is 2, 4 and its electron configuration is [He]2s2 2p2. In its elemental form, carbon can take various physical forms (known as allotropes) based on the type of bonds between carbon atoms; the most well known allotropes are diamond, graphite, amorphous carbon, glassy carbon, and nanostructured forms such as carbon nanotubes, fullerenes, and nanofibers . Carbon is at the same time one of the softest (as graphite) and hardest (as diamond) materials found in nature. It is the 15th most abundant element in the Earth's crust, and the fourth most abundant element (by mass) in the universe after hydrogen, helium, and oxygen. Carbon was discovered by the Egyptians and Sumerians circa 3750 BC. It was first recognized as an element by Antoine Lavoisier in 1789.

Nitrogen

See more Nitrogen products. Nitrogen is a Block P, Group 15, Period 2 element. Its electron configuration is [He]2s22p3. Nitrogen is an odorless, tasteless, colorless and mostly inert gas. It is the seventh most abundant element in the universe and it constitutes 78.09% (by volume) of Earth's atmosphere. Nitrogen was discovered by Daniel Rutherford in 1772.

Tungsten

See more Tungsten products. Tungsten (atomic symbol: W, atomic number: 74) is a Block D, Group 6, Period 6 element with an atomic weight of 183.84. The number of electrons in each of tungsten's shells is [2, 8, 18, 32, 12, 2] and its electron configuration is [Xe] 4f14 5d4 6s2. Tungsten Bohr ModelThe tungsten atom has a radius of 139 pm and a Van der Waals radius of 210 pm. Tungsten was discovered by Torbern Bergman in 1781 and first isolated by Juan José Elhuyar and Fausto Elhuyar in 1783. In its elemental form, tungsten has a grayish white, lustrous appearance. Elemental TungstenTungsten has the highest melting point of all the metallic elements and a density comparable to that or uranium or gold and about 1.7 times that of lead. Tungsten alloys are often used to make filaments and targets of x-ray tubes. It is found in the minerals scheelite (CaWO4) and wolframite [(Fe,Mn)WO4]. In reference to its density, Tungsten gets its name from the Swedish words tung and sten, meaning heavy stone.

Related Forms & Applications