Nitrogen hydrate samples were synthesized using liquid nitrogen and powder ice at 16 MPa and 253 K. Confocal laser Raman spectroscopy was used to investigate the characteristics of nitrogen clathrate hydrates. The res...Nitrogen hydrate samples were synthesized using liquid nitrogen and powder ice at 16 MPa and 253 K. Confocal laser Raman spectroscopy was used to investigate the characteristics of nitrogen clathrate hydrates. The results show that the Raman peaks of N-N and O-H stretching vibration in nitrogen hydrates are observed at 2322.4 and 3092.1 cm^-1, respectively, which are very similar to those in natural air clathrate hydrates. For comparison, we measured the Raman peaks of N-N stretching vibration both in liquid nitrogen and nitrogen molecules saturated water, which appear at 2326.6 and 2325.0 cm^-1, respectively. The Raman spectroscopic observations on the dissociation process suggest that nitrogen molecules occupy both the large and small cages in nitrogen clathrate hydrates. However, only one Raman peak is observed for N N stretching vibration because the difference of the environment of nitrogen molecules between large and small cages is too small to be differentiated by Raman spectroscopy.展开更多
Compared to the widely used carbon-centered radicals,N-radicals have been relatively unexplored owing to the lack of practical and convenient production methods.Over the past few years,benefitting from the resurgence ...Compared to the widely used carbon-centered radicals,N-radicals have been relatively unexplored owing to the lack of practical and convenient production methods.Over the past few years,benefitting from the resurgence of reliable and controllable radical chemistry,N-radicals have been produced via thermal decomposition,oxidants,metal salts,or electrocatalysis.Therefore,numerous N-radical enabled cyclization of 1,n-enynes methods have been developed,providing a versatile and concise synthetic platform for the preparation of complex cyclic systems and natural products containing elaborate ring frameworks.In this review,we will summarize recent advances in the promising field of radical chemistry focusing on the production methods of N-radicals and their cyclization patterns,associated mechanisms,unmet challenges,and future opportunities.展开更多
文摘Nitrogen hydrate samples were synthesized using liquid nitrogen and powder ice at 16 MPa and 253 K. Confocal laser Raman spectroscopy was used to investigate the characteristics of nitrogen clathrate hydrates. The results show that the Raman peaks of N-N and O-H stretching vibration in nitrogen hydrates are observed at 2322.4 and 3092.1 cm^-1, respectively, which are very similar to those in natural air clathrate hydrates. For comparison, we measured the Raman peaks of N-N stretching vibration both in liquid nitrogen and nitrogen molecules saturated water, which appear at 2326.6 and 2325.0 cm^-1, respectively. The Raman spectroscopic observations on the dissociation process suggest that nitrogen molecules occupy both the large and small cages in nitrogen clathrate hydrates. However, only one Raman peak is observed for N N stretching vibration because the difference of the environment of nitrogen molecules between large and small cages is too small to be differentiated by Raman spectroscopy.
文摘Compared to the widely used carbon-centered radicals,N-radicals have been relatively unexplored owing to the lack of practical and convenient production methods.Over the past few years,benefitting from the resurgence of reliable and controllable radical chemistry,N-radicals have been produced via thermal decomposition,oxidants,metal salts,or electrocatalysis.Therefore,numerous N-radical enabled cyclization of 1,n-enynes methods have been developed,providing a versatile and concise synthetic platform for the preparation of complex cyclic systems and natural products containing elaborate ring frameworks.In this review,we will summarize recent advances in the promising field of radical chemistry focusing on the production methods of N-radicals and their cyclization patterns,associated mechanisms,unmet challenges,and future opportunities.
