Pyryliumverbindungen. XVIII, 2-Alkoxy-2H-pyrane aus tetra- und pentasubstituierten Pyryliumsalzen

Pyrylium Compounds. XVIII. 2-Alkoxy-2H-pyrans from Tetra- and Pentasubstituted Pyrylium Salts Alkali alkoxides add regioselectively to 2,3,4,6-tetrasubstituted pyrylium salts 7 (R' H), affording high yields of colourless crystalline 2-alkoxy-2H-pyrans 9 . The latte are also formed simply on refluxing 7 in the corresponding alcohol with triethylamine as proton acceptor. 3,5-Dialkylsubstituted 2,4,6-triarylpyrylium salts react analogously. The 2H-pyran structure of the adducts obtained follows from their n.m.r., i.r., u.v. and mass spectra as well as from their reaction with tetracyanoethylene to cycloadducts of type 10 . Acids regenerate from 9 the original pyrylium cations, whereas reaction of 9 with nitromethane or ethyl cyanoacetate provides benzene derivatives. -- The novel starting pyrylium salts 7b--o are characterized by u.v./vis data and by transformation into the corresponding pyridine derivatives     

Diazoverbindungen. 72. (Diazoalkyl)phosphane – Synthese durch elektrophile Diazoalkansubstitution und oxidative Additionsreaktionen am Phosphor

Diazo Compounds. 72. Diazoalkylphosphanes – Synthesis by Electrophilic Diazoalkane Substitution and Oxidative Addition Reactions at Phosphorus Electrophilic diazoalkane substitution of the diazomethyl compounds 1a,b with the chloro phosphanes 2a-o in the presence of lithium diethylamide yields the diazoalkyl phosphanes 3a-z . Oxidative addition of oxygen, sulfur and selenium at phosphorus leads into the series of oxo, thioxo and selenoxo phosphanes having diazoalkyl substituents ( 4a-d, 5a-m and 7a-d ). The silyl group of 5n,o is cleaved by chromatography on aluminium oxide to yield the (diazomethyl)phosphane sulfides 6a,b .     

Radikalreaktionen an N-Heterocyclen. XI [1] Reaktionen von 3-Methyl-pyrazolin-5-onen mit Phenoxyl-Radikalen

Free Radical Reactions of N-Heterocyclic Compounds. XI. Reaction of 3-Methyl-pyrazolin-5-ones with Phenoxy Radicals Pyrazolin-5-ones ( 3a–i ) were oxidized with 2,4,6-trisubstituted phenoxy radicals ( 2a–d ) to the corresponding radicals ( 4a–i ), which dimerised or combined with phenoxy radical ( 2a ) depending on the R¹- and R⁴-substituents in ( 3 ). In the case of 3-methyl-1-phenyl-pyrazolin-5-one ( 3f ) the primary radical combination products were not found, but the corresponding quinone methide ( 17 ) and the o-phenol derivative ( 18 ) were isolated. Products and yields have been investigated as a function of mol ratio substrate: oxidant and solvent. The radical combination products ( 7–10 ) could de-tertbutylated in the presence of aluminium chloride or in the presence of trifluoroarcetic acid, forming heterocyclic substituted phenols ( 21 ) and ( 22 ).     

Testing the Precision Initiation Couplers

It is possible to properly test a Precision Initiation Coupler (PIC) for its detonation profile and the rotational symmetry of its detonation wave using the Multi-Streak and/or Flash-Gap-Technique both with central linear streak line and circle streak which is comprised of dots for better evaluation.     

Fragment Mass Distribution of “Secondary Fragments”

An analysis of the secondary fragments emerging from a target plate has shown that their mass distribution fits excellently to a formula established earlier by the author. This applies equally well to the secondary fragments of an explosive-formed fragment from a multi-P warhead, to those from the warhead's structural casing. and even to the fragments from the target plate itself, as well as to the sum of all of these 3 types of fragements. The correlation coefficient for the two constant parameters governing this formula (namely, the scaling factor B and the form factor λ) is always better than 0.99, when an optimum total mass M_o is southt and inserted, and when the first, large fragements are not included in the consideration, which means when one or two measured points are negiected. For secondary fragements, the form factor λ in the mass distribution is close to 1/2 = 0.5, whereas for the natural fragments of HE projectiles it is in the order of 2/3. namely, from 0.6 to 0.8.     

Aging Behavior of Propellants investigated by heat generation,stabilizer consumption,and molar mass degradation

Four double-base rocket propellants and a single-base gun propellant were tested to find out stabilizer consumption molar mass degradation, and heat generation between 50 °C and 90 °C and between 40 °C and 110 °C, respectively. Stabilizer depletion was measured by high performance liquid chromatography (HPLC), molar mass degradation by gel permeation chromatography (GPC), and heat generation by microcalorimetry. The conditioning times at different temperatures were determined with one of the rocket propellants, and the influence of the long-term storage on heat generation at 60 °C for 2191 dys was investigated. A correlated experiment between stabilizer consumption and heat generation showed that heat production does not increase substantially until the stabilizer has been consumed almost completely. The experimental data of molar mass degradation are described by a kinetic model based on statistical chain scission, and the stabilizer decrease by a first order reaction. For the gun propellant the Arrhenius plots of the reaction rate constants show two temperatures of teh stabilizer consumption, molar mass degradation and heat generation were determined.     

Bicyclische Oxalamidine – Bausteine für hochsubstituierte 2,2′-Bipyridine und Benzolderivate

Bicyclic Oxalic Amidines as Building Blocks for Highly Substituted 2,2′-Bipyridines and Benzene Derivatives The bis-imidoylchlorides 1 derived from oxalic acid exhibit a high regio- and chemoselectivity. As in the case of 2-picolylamine 2 the acylation with oxalyl chloride furnished the expected open chained oxalic diamides 3a while the imidoylchlorides 1 yield exclusively the new pyrido[1,2-a]-pyrazines 4 . These heterocycles represent readily crystallisable and orange-red coloured compounds with a mesomeric dipolar aromatic substructure. The synthetic value of 4 is based on their easy transformation into highly substituted arenes and hetarenes. Thus, electron deficient dienophiles as dimethyl acetylenedicarboxylate lead to the bipyridines 6 via Hetero-Diels-Alder-Reaction and subsequent 1,5-hydrogen shift. In a complex reaction the derivatives of maleic acid 7a – c yield the bipyridines of type 9 while the new hexasubstituted arenes 10 can be isolated under anaerobic conditions and with an excess of dienophilic component. A x-ray structural determination of 10b shows an alternation of bond lenghts in the benzene ring. This can be considered as a distinct disturbance of aromaticity caused by the arrangement of substituents.     

Barrier-Test

This paper will explain a test configuration for the diagnostic of the shock wave attenuation of homogeneous and sandwiched inert materials, which measures the delay time between the detonation of a donor and an acceptor charge, as well as the detonation profile in the acceptor charge. Applying the double-flash-gap technique, the analyzed pressure levels render possible conclusions about the existence of divergent or convergent detonation waves.