Recent advances on the nitrogen-rich 1,2,4-oxadiazole-azoles-based energetic materials

This review covers recent advances in the synthesis and energetic performance of nitrogen-rich 1,2,4-oxadiazole-azoles-based energetic materials.These materials comprise of 1,2,4-oxadiazole subunit as a key structural motif linked to different nitrogen-rich or nitrogen-oxygen azoles:tetrazole,furazan,furoxan,1,3,4-oxadiazole,pyrazole,and triazole.Particular attention is devoted to the introduction of various energetic groups including nitro,nitramino,azo,azoxy,dinitromethyl,trinitroethyl moieties,and their combination.The physicochemical and available performance parameters including density,decomposition temperature,heat of formation,detonation pressure,detonation velocity,impact sensitivity,and friction sensitivity of typical energetic compounds are also provided and analyzed.Eventually,it was obtained that several screened compounds exhibit superior detonation properties and outstanding insensitivities,which can be classified as a new family of high-performance energetic materials.Additionally,1,2,4-oxadiazole-azoles-based energetic materials still have many thorough works to further exploited and studied,expecting to get very promising insensitive high explosives for practical application and industrialization.

Study on the solid-liquid suspension behavior in a tank stirred by the long-short blades impeller

We investigated the solid–liquid suspension characteristics in the tank with a liquid height/tank diameter ratio of 1.5 stirred by a novel long-short blades(LSB) impeller by the Euler granular flow model coupled with the standard k–ε turbulence model. After validation of the local solid holdup by experiments,numerical predictions have been successfully used to explain the influences of impeller rotating speed,particle density, particle size, liquid viscosity and initial solid loading on the solid suspension behavior,i.e. smaller particles with lower density are more likely to be suspended evenly in the liquid with higher liquid viscosity. At a low impeller rotating speed(N), increase in N leads to an obvious improvement in the solid distribution homogeneity. Moreover, the proposed LSB impeller has obvious advantages in the uniform distribution of the solid particles compared with single Rushton turbine(RT), dual RT impellers or CBY hydrofoil impeller under the same power consumption.

Catalyst-free,direct electrochemical trifluoromethylation/cyclization of N-arylacrylamides using TfNHNHBoc as a CF_(3) source

A new electrochemical strategy for trifluoromethylation/cyclization using TfNHNHBoc as a CF_(3)source was established.This approach was realized by the direct electrolysis of Tf NHNHBoc under external oxidantfree and catalyst-free conditions,and afforded various trifluoromethylated oxindoles with good functional group compatibility and broad substrate scope.Preliminary mechanistic studies show that the reaction proceeds by a radical process.

Tuning Acceptor Length in Photocatalytic Donor-Acceptor Conjugated Polymers for Efficient Solar-to-Hydrogen Energy Conversion

The development of conjugated polymer photocatalysts for efficient solar-to-hydrogen energy conversion is highly desirable for the sustainability of our society.Although the construction of donor-acceptor(D-A)structure in conjugated polymer photocatalysts for solar-to-hydrogen energy conversion has been well documented,less attention has been paid on how large D and how large A units combined together could achieve the best performance.Herein,a series of D-A copolymers P(BDT-DBTSOx)(x=7,19,39,and 79)composed of a benzodithiophene(BDT)donor unit and an oligomeric dibenzo[b,d]thiophene sulfone(DBTSO)acceptor segment were synthesized and studied.It was found that the polymer photocatalytic stabilities under full-arc irradiation improved upon shortening the length of the acceptor segment.Under visible light irradiation and in the presence of 3 wt%Pt cocatalyst,P(BDT-DBTSO79)displayed the best performance with an optimal hydrogen evolution rate of 119.3±5.8 mmol·g^(-1)·h^(-1).This is 1.4-fold as that of DBTSO homopolymer and 22.5-fold as that of BDT/DBTSO alternative copolymer,highlighting the importance of acceptor length in D-A structure for achieving high photocatalytic performance.

Para-selective borylation of monosubstituted benzenes using a transient mediator

Herein,we conceptualized a transient mediator approach that has the capability of para-selective C–H functionalization of monosubstituted aromatics.This approach is enabled by in situ generation of a versatile sulfonium salt via highly electrophilic phenoxathiine or thianthrene dication intermediate which can be readily generated from its sulfoxide with trifluoromethanesulfonic anhydride.Preliminary mechanistic study implied that the remarkable para selectivity might be related to the incredible electrophilicity of thianthrene dication intermediate.The versatility of this approach was demonstrated via paraborylation of various monosubstituted simple aromatics combining the sulfonium salt formation with further photocatalyzed transformation.

Pd-Catalyzed Site-Selective Borylation of Simple Arenes via Thianthrenation

of main observ ation and conclu sion Site-selective borylation of simple arenes was realized in one pot via an electrophilic thianthrenation/Pd-catalyzed borylation sequence.The key to achieve this operatically simple process is the use of Pd catalysis,which could tolerate the solvent and acidic conditions used in the thianthrenation step.This protocol features mild conditions,broad functional group tolerance,and simple manipulations,and is suitable for late-stage functionalization of a wide range of pharmaceuticals and complex bioactive molecules.

Iridium(I)-catalyzed deoxgenation of fluoroalkylsulfoxides with dimethyl diazomalonate to access fluoroalkylthioethers

A new method for the preparation of fluoroalkylthioethers including trifluoromethylthioether and difluoromethylthioether by iridium(Ⅰ)-catalyzed deoxgenation of fluoroalkylsulfoxides with dimethyl diazomalonate was developed.In the reaction system,dimethyl diazomalonate was used as reducing reagent and the corresponding fluoroalkylthioethers were produced through oxygen atom transfer from fluoroalkylsulfoxides to diazomalonate.The protocol featuring effective oxygen atom transfer,mild reaction conditions and good functional groups tolerance offers an alternative strategy for the synthesis of fluoroalkylthioethers.

Synthesis of S-monofluoromethyl phosphorothioates from P^(Ⅴ)-H compounds and PhSO_(2)SCH_(2)F

S-Monofluoromethyl phosphorothioates represent an important class of organofluorine compounds and are re ported here for the first time.A series of S-monofluoromethyl phosphorothioates are conveniently synthesized from different P^(Ⅴ)-H compounds and PhSO_(2)SCH_(2)F under mild conditions.The method is compatible with common functional groups and provides potential opportunities to synthesize new bioactive molecules for medicinal chemistry.

Palladium-Catalyzed Oxidative Annulation of 1-Hydroxy-o-Carborane withInternal Alkynes:Facile Synthesis of Carborane-Fused Oxaborolest

of main observation and conclusion A palladium catalyzed oxidative annulation of 1-hydroxy-o-carborane with internal alkynes via regioselective B(3)—H bond activation has been developed for facile synthesis of a series of QB-substituted carborane-fused oxaboroles.These molecules can undergo intramolecular oxidative dehydrogenative coupling to afford carborane-fused large n systems for potential applications in organic materials.The reaction mechanism is also proposed,involving hydroxy deprotonation,nucleopalladation of alkyne,regioselective electrophilic B—H substitution and reductive eiiimination.

Poly(o-xylylene)s via Cobalt-Catalyzed Reductive Polymerization

Summary of main observation and conclusion Poly(p-xylylene)s(PPX)have found wide applications in various fields owing to their chemical robustness,low gas permeability and excellent dielectric properties.As a structural isomer of PPX,poly(o-xylylene)s(POX),possessing a distinct main-chain connectivity,are excellent candidates to pursue high-performance.materials;however,the investigation of POX is hampered by the.lack of efficient synthetic methods.Herein,we report a straightforward way to access POXs through a cobalt-catalyzed reductive polymerization.This method not only allows the direct preparation of electronically unmodified POXs,but also enables the copolymerization between o-xylylene dibromides bearing different aryl or benzylic substituents.The glass transition temperatures of the copolymers can be finely tuned by varying the ratio between comonomers.The obtained POXs are solvent processible and amenable for thin-film fabrication.As aryl bromide moiety remains untouched during the polymerization,post-polymerization functionalization is easily achieved through Suzuki-Miyaura coupling reaction.The chemistry also enables the copolymerization of xylylene dibromide regioisomers,thereby leading to diversified non-conjugated polymers,whose backbones are rich in arylene moieties.Moreover,the use of the polymerization strategy to synthesize structurally novel porous polymers is demonstrated.