Tetrahydrofuran

About: Tetrahydrofuran is a research topic. Over the lifetime, 11778 publications have been published within this topic receiving 158241 citations. The topic is also known as: diethylene oxide & 1,4-epoxybutane.

A New Synthesis of α,β-Unsaturated Carboxylic Esters. The Condensation of Ethyl Lithiotrimethylsilylacetate with Carbonyl Compounds

Abstract: The key step of the title synthesis involves the conversion of ethyl trimethylsilylacetate to the corresponding enolate, 1, by treatment with lithium dicyclohexylamide in tetrahydrofuran at −78 °C. The condensation of 1 with aldehydes and ketones proceeds smoothly to afford the desired two carbon homologated unsaturated esters in excellent yields. The new process is extended with success to readily-enolizable carbonyl compounds and also to chalcone, which gives no trace of the Michael adduct in the present reaction.

Preparation method of graphene

Abstract: The invention discloses a preparation method of graphene, which comprises the following steps that: hexabromobenzene and substances A are added into solvents, are stirred into a mixed solution and are heated to take reaction for 2 to 48 hours at 100 to 200 DEG C, and a reaction system is oxygen-free or aerobic environment and the normal pressure or pressurized environment in the pressure aspect; the proportion of the hexabromobenzene to the substances A to the solvents is 0.1 to 50mg/0.05 to 500mg/1mL; the solvents are Bis(2-methoxy ethyl)ether, diphenyl ether, diethyl ether, tetrahydrofuran, toluene or benzene; the substances A are CuBr, CuI, CuCl, Cu or Ni. The preparation method has the advantages that the reaction condition is mild, the process is simple, and in addition, good reproducibility is realized. The prepared graphene is single-layer graphene. The graphene is used as chemical reaction raw materials, catalyst carriers and battery electrode materials and has wide application prospects in the aspects of physics and microtronics.

Theoretical and Experimental Studies of the Zwitterion ⇌ Neutral Form Equilibrium of Ampholytes in Pure Solvents and Mixtures

Abstract: The equilibrium ratios for the zwitterionic and neutral forms of the nicotinic and isonicotinic acids (3- and 4-COOH pyridines) have been determined by spectrophotometry in mixtures of water with methanol, tetrahydrofuran and dioxane. The zwitterionic form of the solute is the prevalent structure in mixtures with at least 60% water. In pure organic solvents, the neutral form was found in almost 100%. Ab initio calculations at the MP2/6-311++G**//MP2/6-31G* level predict that the zwitterion is higher in free energy by 33−35 kcal/mol than the neutral tautomer at T = 298 K and p = 1 atm in the gas phase. In contrast, relative solvation free energies, as calculated by the free energy perturbation method in Monte Carlo simulations, are −36, −27, and −15 kcal/mol in water, methanol, and tetrahydrofuran, respectively. The solvent effects for overbalancing the relative internal free energy of the zwitterion and stabilizing this tautomer are large enough only in water and in aqueous solution with water fraction ab...