| | 1 | Author
| Peter Kölle, Heinrich Nöth, RobertT. Paine, Wilfried Rattay | Requires cookie* | | | Title
| Beiträge zur Chemie des Bors, 195 [1] Synthese, Struktur und Reaktionen eines l,3,2,4-Aza-A 3 -phosphadiboretidin-Derivats Contributions to the Chemistry of Boron, 195 [1] Synthesis, Structure and Reaction of a l,3,2,4-Aza-A 3 -phosphadiboretidine Derivative  | | | |
Reference
| Z. Naturforsch. 43b, 1439—1446 (1988); eingegangen am 27. Juni 1988 | | | |
Published
| 1988 | | | |
Keywords
| 1, 3, 2, 4-Azaphosphadiboretidine, 1, 3, 2, 4-Azaphosphoniadiboretidinium-iodid, 1, 3, 2, 4-Selenaazadiboretidine | | | |
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| default:Reihe_B/43/ZNB-1988-43b-1439.pdf | | | | Identifier
| ZNB-1988-43b-1439 | | | | Volume
| 43 | |
| 2 | Author
| Xian-Ming Pan, Eugenie Bastian, Clemens Von Sonntag | Requires cookie* | | | Title
| The Reactions of Hydroxyl Radicals with 1,4-and 1,3-Cyclohexadiene in Aqueous Solution A Pulse Radiolysis and Product Study | | | | Abstract
| The reactions of radiolytically generated hydroxyl radicals and H atoms with 1,4-and 1,3-cyclohexadiene were studied by pulse radiolysis and product analysis. Hydrogen abstraction from these substrates by the OH radical yields the cyclohexadienyl radical (f (310 nm) = 4400 dm 1 mol" 1 cm"' from the reaction of the H atom with benzene) with an efficiency of 50% (0.29 ,«moI /"') in the case of 1,4-cyclohexadiene and 25% (0.15,«mol /"') in the case of 1,3-cyclohexadiene as determined by pulse radiolysis. The remaining OH radicals add to the olefin. In 1,4-cyclohexa-diene the yield of the resulting adduct radicals has been determined in a steady-state "'Co-y-irradiation experiment by reducing it with added 1,4-dithiothreitol (DTT) to 4-hydroxycyc-lohexene. There are two sites of OH radical attack in the case of 1,3-cyclohexadiene, and only the alkyl radical is reduced quantitatively by DTT (G(3-hydroxycyclohexene) = 0.15 ,«mol J '). From material balance considerations it is concluded that the allylic radical must be formed with a G value of 0.28 «mol J~ x but largely escapes reduction by DTT (G(4-hydroxycyclohexene) = 0.03 ,«mol y 1). H atoms add preferentially to the double bonds of 1,4-and 1,3-cyclohexadiene (78% and 93%, respectively), while the O t radical (the basic form of the OH radical) undergoes mainly H-abstraction (92% and 83%. respectively). The radicals formed in these systems decay bimolecularly (2k = 2.8xl0 4 dm' mop 1 s~'). In their combination reactions the cyclohexadienyl radicals form the four possible dimers in propor-tions such that the dienyl radical moiety shows a 2:1 preference to react from its central (la) rather than from a terminal carbon atom (lb). Cyclohexadienyl radicals and the OH-and H-adduct radicals also cross-terminate by disproportionation and dimerization. Material balance has been obtained for the 1,4-cyclohexadiene system in N : 0-saturated solution (10 : mol dm 3) at a dose rate of 0.14 Gy s" 1 , the products (G values in «mol J ') being: benzene (0.085), 4-hydroxycyclohexene (0.25), cyclohexadienyl-dimers (0.144), cyclohexadienyl-OH-adduct-dimers (0.02), OH-adduct-dimers (0.02). Some of the 4-hydroxycyclohexene is formed in an H-abstraction reaction by the OH-adduct radical from 1,4-cyclohexadiene. | | | |
Reference
| Z. Naturforsch. 43b, 1201—1205 (1988); received April 13 1988 | | | |
Published
| 1988 | | | |
Keywords
| 1, 4-Cyclohexadiene, 1, 3-Cyclohexadiene Hydroxyl Radical, Cyclohexadienyl Radical, Pulse Radiolysis | | | |
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| default:Reihe_B/43/ZNB-1988-43b-1201.pdf | | | | Identifier
| ZNB-1988-43b-1201 | | | | Volume
| 43 | |
| 3 | Author
| Bernhard Glaser, ErwinP. Mayer, Heinrich Nöth, Wilfried Rattay, Ulrich Wietelmann | Requires cookie* | | | Title
| Beiträge zur Chemie des Bors, 190 [1] Synthese und Molekülstruktur von 1,2-Dihydroboreten und Azadiboretidinen Contribution to the Chemistry of Boron, 190 [1] Synthesis and Molecular Structure of 1,2-Dihydrodiboretes and Azadiboretidines | | | | Abstract
| [2+2]-Cycloadditions of 9-Fluorenylidentetramethylpiperidinoboranes have been studied with selected olefines, acetylenes and iminoboranes. No reactions with olefines were observed. While propiolic methylester reacts exclusively at the carbonyl bond producing the oxaboretane 5, alkines such as diethylamino-alkines, cyclo-octine and phenylacetylene provide access to the'1,2-dihy-droboretenes 6, 3 and 2. Tetramethylpiperidinoiminoboranes make 1.2.4-azadiboretidines 7 available. 6a and 7a contain a folded four-membered ring as shown by X-ray structure analysis. There is only a weak 1,3-intraannular interaction due to BN-;r-bonding of the boron atoms with their exocyclic amino group. | | | |
Reference
| Z. Naturforsch. 43b, 449—456 (1988); eingegangen am 10. Dezember 1987 | | | |
Published
| 1988 | | | |
Keywords
| Reactivity of Aminomethyleneboranes, Transannular Interaction, X-Ray, 1, 2-Dihydroboret Derivatives, 1, 24-Azadiboretidine Derivatives | | | |
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| default:Reihe_B/43/ZNB-1988-43b-0449.pdf | | | | Identifier
| ZNB-1988-43b-0449 | | | | Volume
| 43 | |
| 4 | Author
| Christa Pomp, Stefan Drüeke, Heinz-Josef Küppers, Karl Wieghardt, Carl Krüger, Bernhard Nuber, Johannes Weiss | Requires cookie* | | | Title
| Synthese | | | | Abstract
| von [LRe(CO) 3 ] + -Komplexen mit makrocyclischen Liganden Die Kristallstrukturen von 1,4,7-TriazacycIononan-tricarbonyl-rhenium(I)-thiocyanat und 1,4,7-Trithiacyclononan-tricarbonyl-rhenium(I) -bromid-hemihy drat Synthesis of [LRe(CO) 3 ]" Complexes with Macrocyclic Ligands The Crystal Structures of l,4,7-Triazacyclononane-tricarbonyl-rhenium(I) Thiocyanate and of l,4,7-Trithiacyclononane-tricarbonyl-rhenium(I) Bromide Hemihydrate The tridentate macrocyclic ligands 1,4,7-triazacyclononane, its thia analogue 1,4.7-trithia-cyclononane, l-oxa-4,7-diazacyclononane, and N,N',N"-trimethyl-l ,4,7-triazacyclononane react with Re(CO) 5 Br in dimethylformamide to yield colorless, air-stable [LRe(CO) 3 ]Br complexes (L = tridentate macrocycle). With Mn(CO) 5 Br only the cyclic amines react to af-ford yellow-orange [LMn(CO),]Br complexes whereas 1.4,7-trithiacyclononane does not give stable complexes of manganese. The crystal structures of [([9]aneN 3)Re(CO) 3 ](NCS) and [([9]aneS 3)Re(CO) 3 ]Br-1/2 H : 0 have been determined. The former crystallizes in the orthorhom-bic space group Pbca (a = 12/763(4), b = 12.662(5), c = 17.472(9) Ä; Z = 8); whereas the latter crystallizes in the monoclinic space group P2,/c (a = 9.444(1). b = 11.797(2), c = 28.095(3) Ä. ß = 90,86(1); Z = 8). | | | |
Reference
| Z. Naturforsch. 43b, 299—305 (1988); eingegangen am 9. Oktober 1987 | | | |
Published
| 1988 | | | |
Keywords
| Crystal Structure, 1, 4, 7-Triazacyclononane 1, 47-Trithiacyclononane Complexes | | | |
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| default:Reihe_B/43/ZNB-1988-43b-0299.pdf | | | | Identifier
| ZNB-1988-43b-0299 | | | | Volume
| 43 | |
| 5 | Author
| Rene Csuk, BrigitteI. Glänzer | Requires cookie* | | | Title
| Biocatalytical Transformations, III [1] Regioselective Enzymic Deacetylations of Laevoglucosane Triacetate | | | | Abstract
| Several hydrolytic enzymes (porcine liver esterase, lipase from wheat germ type I, and the lipase from rhizopus javanicus) efficiently deacetylate laevoglucosane triacetate (2) with good re-gioselectivity into diacetylated laevoglucosane derivatives (3—5). | | | |
Reference
| Z. Naturforsch. 43b, 1355—1357 (1988); received June 3 1988 | | | |
Published
| 1988 | | | |
Keywords
| 1, 6-Anhydro Sugar, Laevoglucosane Triacetate, Deacetylation, Enzymes, Lyophilized Yeast | | | |
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| default:Reihe_B/43/ZNB-1988-43b-1355.pdf | | | | Identifier
| ZNB-1988-43b-1355 | | | | Volume
| 43 | |
| 6 | Author
| Werner Schnurr, Manfred Regitz | Requires cookie* | | | Title
| Phosphorverbindungen ungewöhnlicher Koordination, 31 [1] Cycloaddition von Diazoverbindungen an ein P—Chlor-phosphaalken Phosphorus Compounds with Unusual Coordination, 31 [1] Cycloaddition of Diazo Compounds onto a P—Chloro-phosphaalkene | | | | Abstract
| Chloro bis(trimethylsilyl)methylene phosphane (4) reacts with the diazo compounds 5, 10, 15 and 20 even at low temperatures with formation of the 3H-l,2,4-diazaphospholes 6,11,16 and 21. The products are unstable and decompose either with elimination of nitrogen to yield 1-chloro phosphiranes (9,14, 19 and 22), or isomerize with aromatization (11 —> 13) or transformation into 4,5-dihydro-l,2,4-diazaphospholes (6—> 8, 16—» 18) by trimethylsilyl shifts. Silyl groups attached to ring nitrogen are easily hydrolized (8 —> 7,13 —» 12, 18 —> 17), those attached to ring carbon are cleaved by treatment with potassium fluoride in dimethyl formamide (7 —> 23, 12 —> 24). | | | |
Reference
| Z. Naturforsch. 43b, 1285—1292 (1988); eingegangen am 20. Juni 1988 | | | |
Published
| 1988 | | | |
Keywords
| Chloro-methylene Phosphanes, Diazo Compounds, 1, 2, 4-Diazaphospholes, 1-Chlorophosphiranes | | | |
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| default:Reihe_B/43/ZNB-1988-43b-1285.pdf | | | | Identifier
| ZNB-1988-43b-1285 | | | | Volume
| 43 | |
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