Erick Cuevas-Yañez

Grafting of multiwalled carbon nanotubes with chicken feather keratin

Keratin, obtained from chicken feathers, was grafted on the surface of commercially available carbon nanotubes. The original procedure developed allows a covalent interaction between some specific chemical groups characteristic of the keratin, with some functional groups introduced on purpose on the surface of the nanotubes, as revealed by infrared and Raman spectroscopies, which also allowed to determine structural changes introduced during the process, such as crystallinity, which lead to changes in other properties, as well.

Novel synthesis of primary arylamides from aryl methyl ketone oxidations using iodine in aqueous ammonia

Primary arylamides were obtained when several aryl methyl ketones were treated with iodine in aqueous ammonia at room temperature in goods yields.

Solvent effect in the polyethylene recovery from multilayer postconsumer aseptic packaging

Polyethylene films were separated and recovered from polyethylene-aluminum composites derived from recycling multilayer postconsumer aseptic packaging. A brief study about the separation process by dissolving PE-aluminum (PE-Al) composites into a series of organic solvents with a combination of time and temperature is presented. Through this procedure, 56% polyethylene is recovered from this kind of composites in optimized conditions. DSC and TGA studies were performed to determine the thermal stability of recovered polyethylene films and to establish a comparison with a PE reference commercial product, demonstrating that recovered polyethylene films kept their thermal properties.

Synthesis of (Tetrahydrofuranyl)methyl-1,2,3-triazoles Through Alkyne–Azide Cycloaddition Catalyzed by a Dithioic Acid Copper(I) Complex

Abstract (Tetrahydrofuranyl)methyl-1,2,3-triazoles were synthesized from tetrahydrofurfuryl tosylate and several alkynes in the presence of catalytic amounts of a 3-hydroxy-3-phenyl-2-propenendithioate-bis(triphenylphosphine) copper(I) complex. The reaction process is carried in out under mild conditions, and bases or reducing agents were not used. The reaction afforded the 1,4-regioisomers in excellent yields.

Aluminium Chloride Hexahydrate (AlCl3 · 6H2O): An Efficient, Facile, Mild, And Highly Chemoselective Catalytic Deprotection of Tert-Butyldimethylsilyl (TBS) Ethers

Abstract tert-Butyldimethylsilyl (TBS) phenyl / alkyl ethers were cleaved to the corresponding efficiently parent hydroxyl compounds in good yields using catalytic amounts of AlCl3 · 6H2O by conventional or microwave-assisted heating in methanol or isopropanol solution. Intramolecular and competitive experiments demonstrated the chemoselective deprotection of TBS ethers in the presence of triisopropylsilyl and tert-butyldiphenylsilyl ethers. GRAPHICAL ABSTRACT

Diprotodecarboxylation Reactions of 3,4-Dialkoxythiophene-2,5-dicarboxylic Acids Mediated by Ag2CO3 and Microwaves

Abstract An efficient and rapid method is reported to obtain 3,4-dialkoxythiophenes from 3,4-dialkoxythiophene-2,5-dicarboxylic acids through a diprotodecarboxylation reaction with Ag2CO3/AcOH as a catalytic system and microwave heating in dimethylsulfoxide (DMSO) as solvent. This methodology lets us obtain for the first time good performance with thiophenes bearing strong electron-donating groups such as alkoxides. This methodology eliminates the usage of harmful quinoline as solvent, as well as the long reaction times typically used (12–18 h) to obtain the 3,4-dialkoxythiophenes. The reaction of 7 diacids showed good yields (60–89%) following 20 min of microwave heating in a temperature range of 120–150 °C. [Supplementary materials are available for this article. Go to the publishers online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.] GRAPHICAL ABSTRACT

Alkyne-Azide Cycloaddition Catalyzed by Silver Chloride and “Abnormal” Silver N-Heterocyclic Carbene Complex

A library of 1,2,3-triazoles was synthesized from diverse alkynes and azides using catalytic amounts of silver chloride instead of copper compounds. In addition, a novel “abnormal” silver N-heterocyclic carbene complex was tested as catalyst in this process. The results suggest that the reaction requires only 0.5% of silver complex, affording 1,2,3-triazoles in good yields.

Waste Cellulose from Tetra Pak Packages as Reinforcement of Cement Concrete

The development of the packaging industry has promoted indiscriminately the use of disposable packing as Tetra Pak, which after a very short useful life turns into garbage, helping to spoil the environment. One of the known processes that can be used for achievement of the compatibility between waste materials and the environment is the gamma radiation, which had proved to be a good tool for modification of physicochemical properties of materials. The aim of this work is to study the effects of waste cellulose from Tetra Pak packing and gamma radiation on the mechanical properties of cement concrete. Concrete specimens were elaborated with waste cellulose at concentrations of 3, 5, and 7 wt% and irradiated at 200, 250, and 300 kGy of gamma dose. The results show highest improvement on the mechanical properties for concrete with 3 wt% of waste cellulose and irradiated at 300 kGy; such improvements were related with the surface morphology of fracture zones of cement concrete observed by SEM microscopy.

Chiral bis(amino alcohol) silver complex derived from (+)-camphor

A chiral silver(I) complex was synthesized from the reaction of a chiral amino alcohol derived from (+)-camphor and silver nitrate, with the structure unambiguously disclosed by X-ray analysis and 2-D-NMR experiments. In this complex, the amino alcohol molecule is a monodentate ligand through the amino nitrogen, requiring two amino alcohol units which are coordinated to the silver and located orthogonally through the NH–Ag–NH axis.

A new type of anion receptor: pyrrolyl quinones

The synthesis of a novel 2-dipyrrolyl-2,5-dimethyl-p-benzoquinone is described, and its interactions with fluoride were characterized. An unprecedented interaction between fluoride anions and the quinone ring was observed.