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Graphene is an ultra-thin material, which has received broad interest in many areas of science and technology because of its unique physical, chemical, mechanical and thermal properties. Synthesis of high quality graphene in an inexpensive and eco-friendly manner is a big challenge. Among various methods, chemical synthesis is considered the best because it is easy, scalable, facile, and inexpensive. Different kinds of chemical reducers have been used to produce graphene sheets. However, some chemicals are toxic, corrosive, and hazardous. For this reason, researchers have been using different environmentally friendly substances (termed green reducers) to produce functional graphene sheets. This paper presents an overview and discussion of the green reduction of graphene oxide (GO) to graphene. It also reviews the characterization of GO and its oxide reduction through the analysis of different spectroscopic and microscopic techniques such as Raman spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and atomic force microscopy.

Given the huge dependence on dipolar, aprotic solvents such as DMF, DMSO, DMAc, and NMP in nucleophilic aromatic substitution reactions (SNAr), a simple and environmentally friendly alternative is reported. Use of a "benign-by-design" nonionic surfactant, TPGS-750-M, in water enables nitrogen, oxygen, and sulfur nucleophiles to participate in SNAr reactions. Aromatic and heteroaromatic substrates readily participate in this micellar catalysis, which takes place at or near ambient temperatures.

Secondary allyl alcohols are unreactive under the investigated conditions allowing the selective oxidation of primary allylic alcohols in the presence of secondary allylic substrates.

Optimized conditions allow the silylcupration of various electron-deficient alkynes to give the corresponding products with high E-selectivity.

The highly regioselective title reaction is thought to occur via an argentocarbenium intermediate.

A new synthesis of title chromenopyrrolones (IV) based on the condensation of aminochromenones (I) with α-halo ketones (II) is given.

The development and application of chemical technologies enabling direct analysis of enzyme activity in living systems has undergone explosive growth in recent years. Activity-based protein profiling (ABPP) is a key constituent of this broad field, and is among the most powerful and mature chemical proteomic technologies. This tutorial review introduces the essential features of ABPP and the design and application of activity-based probes (ABPs) from drug target elucidation and in vivo visualisation of enzyme activity to comprehensive profiling of the catalytic content of living systems, and the discovery of new biological pathways.

C 12 H 8 Cl 2 cristallise dans P2 1 avec a=3,976, b=11,558, c=11,166 A, β=91,73°, Z=2; affinement jusqu'a R=0,057. La determination de la structure confirme le schema de la substitution de l'atome Cl du biphenyl deduit des methodes spectroscopiques. L'angle diedre entre les deux groupements phenyl est de 49,6°

The system Y2Co17Cx was investigated by nuclear magnetic resonance zero field spin echo spectroscopy of 89Y. From the satellite line intensity it was deduced that the limiting concentration of the interstitial solution of carbon is very low and corresponds to x = 0.07. The relative insensitivity of the Curie temperature to carbon concentration in this system is in agreement with this behaviour.

Homolytic acylation of methyl 3-amino-2-pyrazinecarboxylates 1a-c under standard Minisci conditions affords the corresponding 5- or 6-monoacylated pyrazines 3a-d or 4a,b in reasonable yields. With 1a, complete selectivity in favor of the 5-acyl products is observed

The effect of humidity on the bismuth superconductor is investigated under 90% humidity at 30°C for 250 h. Nearly none of the peaks of high-Tc phase (2223) can be observed in the X-ray pattern after the test. The silver contact resistance of the sample also increases prominently in the time interval from 60 h to 100 h. When the humidity-tested sample is heated again under sintering conditions (845°C for 50 h in air), the high-Tc phase appears again.

C13H23N3O3.H2O, Mr = 287.36, orthorhombic, P2(1)2(1)2(1), a = 6.3863 (8), b = 14.346 (2), c = 17.247 (2) A, V = 1580.1 (6) A3, Z = 4, Dx = 1.208 g cm-3, lambda(Cu K alpha) = 1.54178 A, mu = 7.04 cm-1, F(000) = 624, room temperature, final R = 0.037 for 1693 reflections with I greater than or equal to 2.5 sigma (I) and 257 variables. The peptide linkage is in a trans conformation. The pyrrolidine ring adopts a puckered C gamma-endo conformation and the leucine side chain is in a twisted [g-(tg-)] conformation. The crystal packing is stabilized by a three-dimensional network of hydrogen bonds which involve all the donor groups. The water molecule plays an important part in the crystal packing, being engaged in three hydrogen bonds with different N-acetylamide molecules.

Laser flash photolysis of para-substituted 3-chloro-3-benzyldiazirines in isooctane produces the corresponding carbenes, which react with pyridine to form ylides or undergo 1,2-H migration to form the (Z)- and (E)-β-chlorostyrenes. The rate for the 1,2-H migration is determined by plotting the pseudo-first-order rate constants for the growth of the ylide vs [pyridine] and extrapolating to zero pyridine concentration, in the case of (p-chlorobenzyl)chlorocarbene, the carbene decay can be monitored directly at 310 nm, whereas in [p-(trifluoromethyl)benzyl]chlorocarbene

X-ray diffraction patterns show that most samples of Y1-x PrxBa2Cu4O8 examined in the present study contained a single YBa2 Cu4O8 (1-2-4) superconductive phase for x 0. The room-temperature resistivity changes linearly until x=0.7 and increases abruptly at x=-0.75. The critical concentration, xcr, thus was estimated to be 0.7. The effective magnetic moments of Pr in Y 1-x PrxBa2Cu4O8 were 3.63., 3.35, and 3.23, μB for x=0.2, 0.4 and 0.6, respectively. In the R0.8 Pr0.2Ba2Cu4O8 system, the depression of Tcweakly depends on the ionic radius of rare-earth elements. Similarities and differences between Y 1-x PrxBa2Cu4O8 and Y1-xPrx-Ba2Cu3O7-y also were noted and are discussed in this paper.

The asymmetric synthesis of (S)-(+)-cryptaustoline was accomplished and found to differ in sign of rotation with the natural «S»-(-)-material. The previously assigned absolute configuration was found to be incorrect and is now corrected. The reversal in stereochemistry came about through an unusual manner involving (S)-(+)-laudanosoline (3) cyclizing to (R)-(-)-cryptaustoline ((-)-1c). The mechanism was explored by oxidation of a series of deuterio derivatives of laudanosoline, all of which retained deuterium in the resultant cryptaustoline

5-(1,3-Benzodioxol-5-ylmethyl)-2-[2-(5-methyl-1H-imidazol-4-ylmethylthio)ethylamino]-4(1H)-pyrimidone dihydrochloride C 19 H 23 N 5 O 3 S 2+ .2Cl - , M r =472.4, triclinic, P1l, a=8.291 (2), b=10.759 (3), c=13.169 (3) A, α=108.42 (2), β=93.28 (2), γ=100.3 (3) o , V=1088.6 A 3 , Z=2, D x =1.44 Mg m -3 , λ(Mo Kα)=0.7107 A, μ=0.42 mm -1 , F(000)=492, T=294 K, final R=0.038 for 3184 unique observed reflexions. All bonded distances and interbond angles lie within the range of values for compounds of a similar nature

1,2-Cyclic sulfates have been prepared from O-protected ricinoleate and ricinelaidate esters. Upon deprotection of the 12-hydroxy moiety, the resulting 12-hydroxy-9,10-cyclic sulfates underwent stereospecific cyclization to the corresponding 2,3,5-trisubstituted tetrahydrofurans. The cyclization occurs by backside attack of the hydroxy oxygen on the distal carbon of the 1,2-cyclic sulfate, with inversion at that center.