Preparation and application of an economical and environmentally friendly hydrate inhibitor in gas field development.

The prevention and control of natural gas hydrates is an important link in ensuring winter production. Traditional thermodynamic inhibitors, like methanol, are commonly utilized due to their low unit costs and pricing, but they come with considerable safety issues when used on-site due to their high toxicity, flammability, and explosive potential. A cost-effective and eco-friendly hydrate inhibitor was created by combining light polyol amine with other ingredients to solve this problem. At a concentration of 30%, the product has a flash point greater than 80°C and a solidification point of -45°C. With success rates of 99% and 100%, respectively, it was used for winter casing pre-injection anti-freezing operations and balancing tank defoamer anti-freezing operations. Experiments have demonstrated the effectiveness of this inhibitor in preventing the formation of natural gas hydrates. In wintertime on-site anti-freezing activities, the projected cost can be substituted for methanol, as it is essentially equivalent to methanol.

Synthesis of Indole-Fused Pyrazino[1,2-a]quinazolinones by Copper(I)-Catalyzed Selective Hydroamination-Cyclization of Alkynyl-tethered Quinazolinones.

We described a copper(I)-catalyzed atom economic and selective hydroamination-cyclization of alkynyl-tethered quinazolinones to prepare a variety of indole-fused pyrazino[1,2-a]quinazolinones in good to excellent yields ranging from 39 %-99 % under mild reaction conditions. Control experiments revealed that coordination-directed method of quinazolinone moiety with copper(I) was important for the selective hydroamination-cyclization of alkynes at the N1-atom instead of N3-atom of quinazolinone. The reaction could be easily performed at gram scales and some prepared indole-fused pyrazino[1,2-a]quinazolinones with donating groups on the indole moiety showed a distinct fluorescence emission wavelength with blue shift under the acid conditions.

Synthesis of 4-(trichloromethyl)pyrido[2',1':3,4]pyrazino[2,1-b]quinazolinones through a cyclized dearomatization and trichloromethylation cascade strategy.

A variety of 4-(trichloromethyl)pyrido[2',1':3,4]pyrazino[2,1-b]quinazolinones were prepared in moderate to good yields with high regioselectivity through intramolecular 6-endo-dig cyclization and trichloromethylation of N3-alkynyl-2-pyridinyl-tethered quinazolinones in chloroform. Mechanistic studies revealed that chloroform might serve as a trichloromethyl anion precursor. Furthermore, the reaction could be easily performed on gram scales and an estrone-derived 4-(trichloromethyl)pyrido[2',1':3,4]pyrazino[2,1-b]quinazolinone was prepared over five steps. The present method features broad substrate scope, good functional group tolerance, new dearomatization of pyridine rings, and chloroform as the trichloromethylation reagent.