Isopolymorphie bei 1,2,4-Chlor- und 1,2,4-Bromdinitrobenzol

Ohne ZusammenfassungMit 1 AbbildungDiese Arbeit wurde im Feber 1944 bei der Zeitschrift Physikal. Chemie eingerichtet und konnte dort aus kriegsbedingten Gründen nicht erscheinen.     

Synthesis of 1,2,4-triazoles and 1,2,4-oxadiazoles

Monothiodiacylamines reacted regiosepecifically with hydrazines and hydroxylamine to give substituted 1,2,4-triazoles and 1,2,4-oxadiazoles in excellent yields.     

1,2,4-Triazines X: Dimerizations of 1,2,4-triazmes

5,5′-Bi-1,2,4-triazinyl compounds are obtained by the treatment of 5-unsubstiluted 1,2,4-triazines with either sodium methoxide or with aqueous potassium cyanide. 5,5′-Bi-1,2,4-triazinyl is also obtained by the reaction of 1,2,4-triazine with potassium cyanide. It is proposed that the sodium methoxide catalyzed dimerizations occur via a carbanionic intermediate; the aqueous potassium cyanide catalyzed reactions via a cyanide addition product and the potassium in liquid ammonia reaction via a free radical dimerization process.     

1,2,4-Azadiphosphole

tert-Butylaminophosphaalkyne 4 is shown to dimerize in alkaline medium to 1-tert-butyl-3-tert-butylamino-1,2,4-azadiphosphole 1 —the first representative of 1,2,4-azadiphospholes. The structure of 1 has been determined by IR and ³¹P NMR spectroscopy and by X-ray crystallography. Compound 1 crystallizes in the triclinic space group P¯1 with a = 10.356(7), b = 11.817(5), c = 11.830(3) Å, α = 88.51(3), β = 78.61(4), γ = 77.05(4)°, V = 1383(1) ų, Z = 4 (two independent molecules).     

1,2,4-Oxadiazoles. X. Aryl-1,2,4-oxadiazolecarbaldehydes

The synthesis of 5-aryl-1,2,4-oxadiazole-3-carbaldehydes and 3-aryl-1,2,4-oxadiazole-5-carbaldehydes was attempted through several routes and achieved starting from both the corresponding chloromcthyl and the dichloromethyl derivatives. These aldehydes are stabilized in the hydrated form and this peculiar behavior is discussed on the basis of the relevant spectroscopic data.     

SYNTHESES AND REACTIVITY OF SOME 1,2,4-THIADIAZOLOAZINES AND 1,2,4-THIADIAZOLOAZOLES

Abstract

Recently, we have prepared a number of N-ethoxycarbonyl-N′-(2-azinyl)thioureas, which could be cyclized by oxidation into derivatives of 1,2,4-thiadiazolo/2,3-a/azines.     

3,5-Disubstituted-1,2,4-oxadiazoles and 4,5-dihydro-3,5-disubstituted-1,2,4-oxadiazoles

A series of 3,5-disubstituted-1,2,4-oxadiazoles ( 2 ) were prepared from a mono- or dichlorophenyl-substituted amidoxime and (i) an acid chloride, (ii) an isatoic anhydride, or (iii) a β-keto ester. Although cyclizations of the same amidoximes with acetaldehyde gave 4,5-dihydro-5-methyl-substituted derivatives ( 5 ), that annulation procedure either failed or gave low yields with other aldehydes. A novel alternative method, the diborane reduction of 2 , has been found to be a generally applicable procedure for preparing 5 . The reduction is regioselective, i.e., only the 4,5-(C=N) linkage is reduced even when a large excess of diborane is present.     

The preparation of 1,2,4-Triazines and 1,2,4-Triazolines from substituted carboxamide hydrazones

Substituted carboxamide hydrazones have been condensed with 2,3-butanedione and with glyoxal to form 1,2,4-triazines; with benzaldehyde and pyridine-2-carboxaldehyde to yield 1,2,4-triazolines.     

Synthesis of amino-1,2,4-triazoles by reductive ANRORC rearrangements of 1,2,4-oxadiazoles

The reaction of various 1,2,4-oxadiazoles with an excess of hydrazine in DMF has been investigated. 3-Amino-1,2,4-triazoles are produced through a reductive ANRORC pathway consisting of the addition of hydrazine to the 1,2,4-oxadiazole followed by ring-opening, ring-closure, and final reduction of the 3-hydroxylamino-1,2,4-triazole intermediate. The general applicability of 1,2,4-oxadiazoles ANRORC reactivity is demonstrated also in the absence of C(5)-linked electron-withdrawing groups.     

Mass spectra of 1,2,4-triazoles—II: Alkyl 1,2,4-triazoles

The mass spectra of monomethyl 1,2,4-triazoles contain fragment ions produced by specific cleavage of the heterocyclic ring. A major fragmentation from many molecular ions involves the elimination of HCN, but loss of N₂ is either very small or completely absent. No N or H scrambling occurs within the triazole ring system, as evidenced by labelling studies. The loss of a hydrogen atom from the molecular ions of 3-alkyl-1,2,4-triazoles (alkyl ? C₂H₅) originates from hydrogens attached to the β carbon and nitrogen atoms.     

1,2,4-triazolium-cation-based energetic salts

3,4,5-Triamino-1,2,4-triazole (guanazine, 1) can be readily methylated with methyl iodide yielding methylguanazinium iodide (2). Salts containing the novel methylguanazinium cation with energetic anions were synthesised by metathesis reactions with silver azide (3), silver nitrate (4), silver perchlorate (5), sodium 5,5'-azotetrazolate (6), silver 5-nitrotetrazolate (7) and silver dinitramide (8), yielding a new family of heterocycle-based salts, which were fully characterised by analytical (mass spectrometry and elemental analysis) and spectroscopic methods (IR, Raman and NMR). In addition, the molecular structures of all compounds were confirmed by X-ray analysis, revealing extensive hydrogen-bonding in the solid state and densities between 1.399 (3) and 1.669 g cm(-3) (5). The hydrogen-bonded ring motifs are discussed in the formalism of graph-set analysis for hydrogen-bond patterns and compared to each other. Preliminary sensitivity testing of the crystalline compounds indicate surprisingly low sensitivities to both friction and impact, the highest friction and shock sensitivity being found for the perchlorate (5, 220 N) and the dinitramide (8, 20 J) salts, respectively. In addition, DSC analysis was used to assess the thermal stabilities of the compounds: 3-6 melt above 200 degrees C with concomitant decomposition, whereas 7 and 8 have clearly defined melting points at 162 and 129 degrees C, respectively, and with decomposition occurring about 30 degrees C above the melting point. Lastly all compounds have positive calculated heats of formation between 336 (4) and 4070 kJ kg(-1) (6) and calculated detonation velocities in the range between 8330 (7) and 8922 m s(-1) (6) making them of interest as new highly energetic materials with low sensitivity.     

Construction of Coplanar Bicyclic Backbones for 1,2,4-Triazole-1,2,4-Oxadiazole-Derived Energetic Materials

Combining different nitrogen-rich heterocycles into a molecule can fine-tune its energetic performance and physical properties as well as its safety for use in energetic materials. Here, 1,2,4-oxadiazole was incorporated into 1,2,4-triazole to construct new energetic backbones. 3-(5-Amino-1H-1,2,4-triazol-3-yl)-1,2,4-oxadiazol-5-amine ( 5 ) was designed and synthesized. Nitramino-functionalized N-(5-(5-amino-1,2,4-oxadiazol-3-yl)-3H-1,2,4-triazol-3-yl)nitramide ( 6 ) and N-(5-(5-(nitramino)-1,2,4-oxadiazol-3-yl)-3H-1,2,4-triazol-3-yl)nitramide ( 7 ) were also obtained, and two series of corresponding nitrogen-rich salts were prepared, leading to the creation of new energetic compounds. All derivatives were fully characterized, and five of them were further confirmed by X-ray diffraction. The theoretical calculations, energetic performance, safety, and the main decomposition gaseous products of 1,2,4-triazole-1,2,4-oxadiazole-derived energetic materials were studied. Compound 7 and its dihydroxylammonium salt ( 7 c ) exhibited prominent detonation performance comparable to that of RDX while possessing satisfying thermal stabilities and mechanical sensitivities.     

Synthesis of 1,2,4-trioxepanes and 1,2,4-trioxocanes via photooxygenation of homoallylic alcohols

Homoallylic alcohols 4a-d, easily accessible in two steps from cyclopropyl methyl ketone, underwent a highly regioselective reaction with singlet oxygen to yield gamma-hydroxyhydroperoxides 5a-d in 57-72% yield. Acid-catalyzed reaction of 5a-d with acetone, cyclopentanone, and cyclohexanone furnished 1,2,4-trioxepanes 8a-d, 9a-d, and 10a-d in good yields. Homoallylic alcohol 12 also underwent a highly regioselective photooxygenation to yield gamma-hydroxyhydroperoxide 13 in 67% yield, which on reaction with acetone, cyclopentanone, and cyclohexanone, furnished 1,2,4-trioxocanes 16-18 in 41-55% yield.     

Merocyaninfarbstoffe aus 1,2,4-Triazin

Zusammenfassung Hydrazinderivate von 1,2,4-Triazinen liefern mit Acetessigester Pyrazolonderivate. Diese kondensieren sich mit Salzen quartärer heterocyclischer Basen zu Merocyaninfarbstoffen. Darstellung und Spektren von drei Typen solcher Farbstoffe werden beschrieben.

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Hydrazine derivatives of 1,2,4-triazines with acetoacetic ester yield the corresponding pyrazolones. These condense with salts of quaternary heterocyclic bases to merocyanin dyes. The preparation and the spectra of three types of such dyes are described.

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Mit 1 Abbildung     

3,3-Dinitrobutyl-1,2,4-oxadiazoles

The syntheses of 3,5-bis(3,3-dinitrobutyl)-1,2,4-oxadiazole and a series of 3-aryl-5-(3,3-dinitrobutyl)-1,2,4-oxadiazoles were accomplished by treating 4,4-dinitropentanoyl chloride with the appropriate amidoximes to yield the intermediate O-(4,4-dinitropentanoyl)amidoximes, which were dehydrated to the 1,2,4-oxadiazoles.     

Synthesis of triterpenoid-based 1,2,4-trioxolanes and 1,2,4-dioxazolidines by ozonolysis of allobetulin derivatives

Oxidation of allobetulin derivatives with ozone results in good isolated yields of 1,2,4-trioxolanes and stable 1,2,4-dioxazolidines. Individual 3R,5R and 3S,5S diastereoisomers of allobetulin secondary ozonides were isolated and their structures confirmed by X-ray crystallographic analysis. Remarkable diastereoselectivity with formation of only the (3S,5S)-configured peroxides was observed during the oxidation of 1,5-di-O-methoxyoximinoallobetulin to dioxazolidines.