Recent Advances in the Synthesis of Isocoumarins and Polyaromatic Hydrocarbons for Photoactive Materials

The discovery of transition metal-catalyzed selective activation of aromatic carbon–hydrogen bonds in 1993 has opened a new era in the synthesis of carbo- and heterocyclic compounds. This review covers the applications of oxidative annulations of aromatic compounds with alkynes involving CH activation for the synthesis of isocoumarins and polyaromatic hydrocarbons (PAHs). The limitations, advantages, and mechanical aspects of this approach as well as the current tendencies in the application of the reaction products for photoactive materials are discussed.

Ruthenium Metal: Uplifting Regioselective C-H activation

: Construction of the C-C bond has always been a challenge for organic chemists, because of the reactivity of carbon atoms. The making of nucleophilic carbon started with the Grignard reagent, enolate, and the ylide, moreover, the aromatic carbon activation was the challenge before the era of organometallic chemistry. The recognition of organometallic chemistry was in the light when the Nobel Prize was given for the C-C bond in the year 2010, However, The pre functionalization of the C-H bond was an additional step with halogenated reagent, which was the limitation of this reaction. Later the C-H activation with organometals like Pd, Ru, Cu, Rh, and other transition metal came into existence, where the directing group and metal makes feasibility to form the nonreactive C-C bond. In spite of several organometals, Ru made a special place due to the reactivity, coast and, stability. Various C-H activation reaction protocols were reported with their high regioselectivity as well as high atom economy. The C-H activation protocol is now in the next level of development like SP3, SP2 ortho, meta, and para C-H activation. Here in our aim is to get the summarized information regarding the Ru and their ortho -regioselective reactions with the help of the directing group. The reader will be benefited from the mechanistic part and the concept of C-H activation with some of the important examples, which have been summarized here in with the various Ru based regioselective reactions through weak and strong coordination of metal and substrate.

Effects of Oxygen Partial Pressure on Wood-Based Activated Carbon Treated with Vacuum Ultraviolet Light

This study uses vacuum ultraviolet (VUV) light with a wavelength of 172 nm as a surface treatment to enhance the adsorption capacity of wood-based activated carbon (AC). The AC surface treatment is performed under three O2 partial pressure conditions—5.0 × 104 Pa, where ozone (O3) effects dominate; 6.3 × 10−6 Pa, where VUV effects dominate; and 1.9 × 103 Pa for a balanced condition. For the O3-dominant condition, only graphene edge defects are etched (no aromatic carbon bonds are etched), resulting in increased surface roughness. When the VUV effects dominate, aromatic carbon bonds are cleaved, which then reacted with O2 or water adsorbed inside the pores. This increased both the number and size of the mesopores. Under the balanced conditions, the water adsorption capacity was enhanced by 45.5%, which is higher than that obtained before VUV exposure or with VUV under other conditions. This is because the surface roughness increased, as well as the pore sizes and numbers under the balanced condition. These results indicate that we can control VUV-based AC surface treatments via O2 partial pressure.

Preparation and Characterization of Composite from Poly(vinyl chloride) Hydrochar and Hydrolyzate of Keratin from Chicken Feather by Hydrothermal Carbonization

Poly(vinyl chloride) and chicken feather wastes considered as the dangerous wastes. This study aimed to characterize the prepared composite from poly(vinyl chloride) hydrochar and keratin hydrolyzate from chicken feather to get possibility the usage of this composite as soil amendment. The poly(vinyl chloride) hydrochar-keratin hydrolyzate composites (HKHC) had been produced with the hydrothermal carbonization process. The composites were made from different composition of poly(vinyl chloride):chicken feather (5:95% (HKHC5), 10:90% (HKHC10) and 15:85% (HKHC15)). The hydrothermal carbonization process would break and fracture the CHCl bond of poly(vinyl chloride). Moreover, this process would also hydrolyze keratin from chicken feather into small protein. The composite structure was formed from aromatic carbon and amino acids aggregate along with other organic substances. The solid composites and liquid residues formed in this process. The composites were characterized by FTIR, XRD and TEM and the composite of char-Fe3O4 was characterized by SEM. Meanwhile, the liquid residues were analyzed for its organochlorine by GC-MS and amino acid contents by HPLC. The results showed that all products have similar properties but the composite with ratio 5:95% (HKHC5) had the highest aromatic structure, paramagnetic (Fe3O4) crystallinity and amino acid contents.

Conversion of anilines to chiral benzylic amines via formal one-carbon insertion into aromatic C–N bonds

Insertion of atoms into aromatic carbon-nitrogen bonds is an appealing method for the synthesis of nitrogen-containing molecules and it has the advantage of the availability and abundance of anilines. However, the direct cleavage of aromatic carbon-nitrogen bonds is challenging due to the particularly inert and stable nature of these bonds. Here we report a formal, enantioselective one-carbon insertion into an aromatic carbon-nitrogen bond via an aromaticity dissembly-reconstruction process to directly convert anilines to chiral α-branched benzylic amines. The process involves oxidative dearomatization of para-substituted anilines, chiral sulfur ylide-mediated asymmetric aziridination, and subsequent rearrangement. Chiral sulfur ylides serve as one-carbon insertion units.