Green chemistry approaches to the regioselective synthesis of spiro heterobicyclic rings using iodine as a new and efficient catalyst under solvent-free conditions

Abstract  

Iodine catalyzes the pseudo four-component reaction of an aldehyde, a urea or thiourea, and cyclic 1,3-dicarbonyl compounds under microwave irradiation in a solvent-free condition to yield various σ symmetric spiro heterobicyclic rings in excellent yields.     

Preparation of phenolic compounds through catalyst-free ipso-hydroxylation of arylboronic acids

A novel method for the preparation of phenolic compounds through ipso-hydroxylation of the corresponding widely available arylboronic acid precursors is described. Through application of a novel PEG400-H₂O₂ reactant system, a variety of substituted phenols and other aromatic analogues have been prepared in excellent yields at room temperature in the absence of any catalyst.     

Iodine-Catalyzed Highly Effective Pictet–Spengler Condensation: An Efficient Synthesis of Tetrahydro-β-carbolines

Molecular iodine was found to be an efficient catalyst for the two-component Pictet–Spengler condensation of tryptamine with aldehydes, which leads to the formation of tetrahydro-β-carbolines in high yields.     

A Visible Spectroscopic Study of Microstructure of O/W Microemulsions of Anionic Surfactants: Effect of Cosurfactant

The microstructure of o/w microemulsions, stabilized by sodium dodecyl benzene sulfonate (SDBS) and sodium dodecyl sulfate (SDS) with different cosurfactants, has been studied by partitioning of a dye, phenol red, between the oil‐water interface and bulk water. The cosurfactants used are propan‐1‐ol, propan‐2‐ol, butan‐1‐ol, butan‐2‐ol, pentane‐1‐ol, pentane‐2‐ol, and pentan‐3‐ol. The effects of changing the oil volume fraction and surfactant‐cosurfactant w/w ratio on the oil‐water interface and droplet size have also been discussed. Larger droplet size was predicted for SDS than SDBS. The predicted droplet radius increased with increase in the oil fraction, decrease in the surfactant concentration, increase in the C‐number of the linear cosurfactant, and decrease in branching of the cosurfactant. Surfactant‐cosurfactant ratio and pH did not affect the droplet size significantly. The minimum concentrations of surfactants with which microemulsions were formed were found to be higher for larger oil fraction, smaller C‐number of the alcohol, more branching of the alcohol, and higher pH.     

Al(OTf)3-catalyzed one-pot synthesis of pyrrolo[3,2-d]pyrimidinedione derivatives

A series of polysubstituted pyrrolo[3,2-d]pyrimidinedione derivatives have been synthesized in excellent yields. This prominent scaffold is obtained via an Al(OTf)₃-catalyzed tandem addition-annulation sequence between propargylic alcohols and aminopyrimidines. The process is simple, facile, inexpensive, and provides a diverse range of substituted pyrrolo [3,2-d]pyrimidinedione derivatives with short reaction times from readily obtainable starting materials.     

Relative proton transfer abilities of acids and alcohols in gas phase and solutions

The present paper applies a method, based on SCF CNDO MO charge densities and assumption of the validity of the virial theorem, for calculation of relative proton affinities of alcohols, and substituted and unsubstituted carboxylic acids in the gas phase. The paper also chalks out a path for calculation of their relative acidities in solution phase by utilising a solvation energy equation and binding energy data in the gas phase. The results obtained by the present method are mostly in agreement with ion cyclotron resonance mass spectrometric experimental studies. The method has also been applied to cover the cases of amines in the gas phase.     

Nature of the emission band of Dergaon meteorite in the region 5700x2013;6700 Å

An emission band system in the region 5700–6700 Å from Dergaon stoney iron meteorite which fell at Dergaon, India on March 2, 16.40 local time (2001) was excited with the help of a continuous 500 mW Ar⁺ laser. The band system is attributed to silicate (olivine), a major component of the meteorite.     

FT—IR测定内燃机油中氧化值和硝化值

使用ＮＩＣＯＬＥＴ２０ＤＸＢ傅里叶变换红外光谱仪，应用差示红外，应用差示红外光谱法经过规定的台架试验后内燃机油中氧化值和硝化值。考察了台架试验条件，试验时间时间对内燃机油中氧化值和硝化值的影响。