30007-47-7Relevant articles and documents
Reactivity of 13,13-dibromo-2,4,9,11-tetraoxadispiro[5.0.5.1]tridecane toward organolithiums: Remarkable resistance to the DMS rearrangement
Eccles, Wendy,Jasinski, Marcin,Kaszynski, Piotr,Zienkiewicz, Katarzyna,Stulgies, Baldur,Jankowiak, Aleksandra
, p. 5732 - 5744 (2008/12/22)
(Chemical Equation Presented) Reactions of dibromocyclopropane 2a, containing two spiro-fused 1,3-dioxane rings, with MeLi gave only the methylation products 8 and 9 even at elevated temperatures. In contrast, the cyclohexane analogue 2b treated with MeLi underwent a smooth rearrangement to bicyclo[1.1.0]butane 11b at -78, -10, or +35 °C. Treatment of 2a with PhLi gave the α-Ph anion 13 as the only product, which underwent smooth methylation with MeI to give 14. Under the same conditions, 2b with PhLi gave bicyclo[1.1.0]butane 11b accompanied by bromophenyl derivative 8b. Treatment of either dibromide with f-BuLi gave a mixture of products including debrominated cyclopropanes 12. Experimental results were augmented with DFT calculations for salts 23 and MP2//DFT-level calculations for carbenes 22. They demonstrated a higher stability of the dioxane α-bromo anion with respect to α-elimination by 4.8 kcal/mol and also a lower tendency of the carbene 22a to undergo rearrangement by 4.0 kcal/mol than the cyclohexane analogues. These differences have been attributed to the inductive effect of the four oxygen atoms, which results in lower LUMO energy, the higher positive charge at the carbenic center, and the overall more electrophilic character of carbene 22a as compared to the cyclohexane derivative 22b. The rearrangement of carbenes 22 to the corresponding allenes 1, the thermodynamic products, requires a higher activation energy ΔG?298 by 4.2 kcal/mol for dioxane and 6.4 kcal/mol for cyclohexane derivatives than for the formation of the bicyclo[1.1.0]butanes 11. The ΔG?;298 for intramolecular insertions to the C-H bond is low and calculated as 6.0 kcal/mol for dioxane 22a and 2.0 kcal/mol for the formation of cyclohexane 22b.
Aqueous isothiazolone formulation
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, (2008/06/13)
An aqueous isothiazolone formulation useful for antiseptic or antifungal treatment of various synthetic polymeric emulsions, which comprises (a) a specific isothiazolone compound, (b) water or an aqueous solvent and (c) a specific nitrobromo or cyanobromo compound.
REACTION OF 5-BROMO-5-NITRO-1,3-DIOXANE WITH THE LITHIUM SALTS OF 5-NITRO-1,3-DIOXANE AND 2-NITROPROPANE
Zorin, V.V.,Kukovitskii, D.M.,Zlot-skii, S.S.,Todres, Z.V.,Rakhmankulov, D.L.
, p. 785 - 789 (2007/10/02)
5-Nitro-5-(5-nitro-1,3-dioxa-5-cyclohexyl)-1,3-dioxane and 5-(1,3-dioxa-5-cyclohexylidene)-1,3-dioxane are formed and lithium bromide and nitrite are released in the reaction of 5-bromo-5-nitro-1,3-dioxane with the lithium salt of 5-nitro-1,3-dioxane in DMSO at 20 deg C.The selectivity of the formation of the reaction products depends on the ratio of the reagents. 5-Nitro-5-(2-nitro-1-methylethyl)-1,3-dioxane, 5-nitro-5-(5-nitro-1,3-dioxa-5-cyclohexyl)-1,3-dioxane, and 2,3-dimethyl-2,3-dinitrobutane are formed in the reaction of 5-bromo-5-nitro-1,3-dioxane with the lithium salt of 2-nitropropane.The reaction is accelerated by UV radiation and is retarded in the presence of the inhibitors of radical reactions.
