silica sulfuric acid as an efficient and reusable heterogeneous catalyst has been used for the preparation of amidines 2 from formimidate 1 by reaction with aromatic amines at room temperature in good to excellent yields. imidate was prepared by treatment of equimolar quantities of triethyl orthoformate and diaminomaleonitrile in refluxing dioxane. all the compounds were characterized fully by ...

the aryl-(z)-n-[2-amino-1,2-dicyanovinyl]formamidine 2 cyclize in solvent-free conditions and in the presence of a base to give a 5-amino-1-aryl-4-cyanoimidazoles 3. silica sulfuric acid as an efficient and reusable heterogeneous catalyst has been used for the preparation of amidines 2 from formimidate 1 through reaction with aromatic amines at room temperature and in good to excellent yields. ...

a novel and safe method for nitration of phenols, anilines and other aromatic compounds has beenfound to be feasible with alumina sulfuric acid (asa) as catalyst and mg (no3)2.6h2o as nitrating agent inneat water as solvent. the use of water makes this method compatible with the green chemistry approach

cellulose sulfuric acid as a bio-polymer based solid catalyst efficiently catalyzes the selectively oxidation of sulfides to sulfoxides and thiols to disulfides using hydrogen peroxide as a green oxidant with good yields at room temperature. the developed method offers a number of advantages such as high selectivity, mild reaction conditions, simple operation, cleaner reaction profiles, low cos...

It is well established that the bacterium Thiobacillus thiooxidans is capable of growing in very strong mineral acid solutions and of producing, from elementary sulfur, sulfuric acid solutions more concentrated than 1 N and a reaction considerably below pH 1. This organism had been considered unique in its tolerance to acid until Starkey and Waksman (1943) demonstrated that certain fungi, Acont...

A LTHOUGH MANY METHODS have been published for the determination of pregnanediol in urine, we found none of them fully satisfactory. The first gravimetric method (1), and colorimetric methods derived from this one (2, 3), are rather unspecific, because, especially under pathologic conditions, fairly large amounts of similar compounds are found in the so-called pregnanediol fraction. Determinati...

Isopropyl alcohol has been called the first petrochemical (IARC, 1992). It can be prepared via three different methods: indirect hydration of propylene, direct hydration of propylene, and catalytic hydrogenation of acetone. Indirect hydration, also called the sulfuric-acid process, was the only method used to produce isopropanol worldwide until the first commercial direct-hydration process was ...

Sugarcane bagasse contains cellulose, lignin and hemicellulose, 39-42%, 20-25% and 25-27% respectively. So it is can be used as a sugar source in many processes. Lignin and hemicellulose must be removed before hydrolysis of cellulose. Several different pretreatment approaches have been studied. The purpose of this research is comparison of acid, ozone and combination of ozone-acid as pretreatme...

a new model is proposed in this research to calculate the longitudinal strengthof unidirectional e-glass reinforced polymer composites exposed to sulfuricacid environment, using a micromechanics model. in the proposed method,it is assumed that the residual strength of the degraded composites under acidic environment can be calculated by knowing the degraded strength properties of the constituen...