- Synthesis and bactericidal activity of substituted cyclic acetals
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A series of substituted cyclic acetals were synthesized and tested for their bactericidal activity against bacteria strain Azospirillum brasilense Sp245.
- Tugarova,Kazakova,Kamnev,Zlotskii
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p. 1930 - 1933
(2015/02/02)
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- Identification of 1,3-dioxanes and 1,3-dioxolanes as malodorous compounds at trace levels in river water, groundwater, and tap water
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A study of organic compounds imparting odor problems in river waters and groundwaters has been conducted. The Tordera aquifer located in Barcelona and Girona (NE Spain) is the water supply reserve for many seasonally crowded villages on the coast. Closed loop stripping analysis (CLSA) and flavor profile analysis (FPA) have been employed as analytical tools to identify the compounds responsible for the odor complaints. The feasibility of purge-and- trap (P and T) has also been evaluated. The 2-alkyl-5,5-dimethyl-1,3-dioxanes and 2-alkyl-4-methyl-1,3-dioxolanes were the most significant compounds identified in river water and groundwater with a threshold odor of 10 ng/L for 2-ethyl-5,5-dimethyl-1,3-dioxane (2EDD), the most malodorous compound. The analyses were carried out by HRGC/MS, and the synthesized 1,3-dioxanes and dioxolanes were characterized by CI-MS and EI-MS/MS techniques. A company, currently manufacturing saturated and unsaturated polyester resins, located in the upper course of the river, produced these compounds as byproducts during the synthesis of resins. The pollution by dioxanes and dioxolanes affected all the aquifer and slowly diminished to the ppt levels when the company was forced to correctly treat their wastewaters. Additional examples of the presence of dioxanes and dioxolanes in wastewaters of other resin plants and also tap water of Barcelona are shown. A study of organic compounds imparting odor problems in river waters and groundwaters has been conducted. The Tordera aquifer located in Barcelona and Girona (NE Spain) is the water supply reserve for many seasonally crowded villages on the coast. Closed loop stripping analysis (CLSA) and flavor profile analysis (FPA) have been employed as analytical tools to identify the compounds responsible for the odor complaints. The feasibility of purge-and-trap (P&T) has also been evaluated. The 2-alkyl-5,5-dimethyl-1,3-dioxanes and 2-alkyl-4-methyl-1,3-dioxolanes were the most significant compounds identified in river water and groundwater with a threshold odor of 10 ng/L for 2-ethyl-5,5-dimethyl-1,3-dioxane (2EDD), the most malodorous compound. The analyses were carried out by HRGC/MS, and the synthesized 1,3-dioxanes and dioxolanes were characterized by CI-MS and EI-MS/MS techniques. A company, currently manufacturing saturated and unsaturated polyester resins, located in the upper course of the river, produced these compounds as byproducts during the synthesis of resins. The pollution by dioxanes and dioxolanes affected all the aquifer and slowly diminished to the ppt levels when the company was forced to correctly treat their wastewaters. Additional examples of the presence of dioxanes and dioxolanes in wastewaters of other resin plants and also tap water of Barcelona are shown.
- Romero, Jordi,Ventura, Francesc,Caixach, Josep,Rivera, Josep,Gode, Llui Xavier,Ninerola, Josep Ma.
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p. 206 - 216
(2007/10/03)
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- Acetolysis of Cyclic Acetals: Regioselective Acylative Cleavage of Cyclic Formals
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The acid-catalyzed reaction of cyclic acetals with acetic anhydride has been investigated.Acylative cleavage of cyclic formals has been found to be a clean, high-yield reaction involving rupture of the C(2)-O bond with loss of stereochemical integrity at the C(2)-position to give hemiacetal acetate products.Ring cleavage of unsymmetrically substituted cyclic formals with either acetic anhydride or acetyl chloride occurs via preferential rupture of the less congested C(2)-O bond (Scheme I, path A).Such cleavage is totally regiospecific for 1,3-dioxanes and displays high (75-85percent) regioselectivity for smaller and larger ring systems.Acetolysis of cyclic acetals other than formals is a slow process that leads to loss of the aldehyde derived fragment and formation of simple diacetates.These results are rationalized in terms of rate-limiting electrophilic attack that is acutely sensitive to steric effects engendered by substituents located at positions adjacent to ring oxygens.
- Bailey, William F.,Rivera, Alberto D.
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p. 4958 - 4964
(2007/10/02)
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- REACTION OF CYCLIC ACETALS WITH 1,3-DIOXANIUM SALTS
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The products from reaction of 1,3-dioxacycloalkanes with 1,3-dioxanium tetrafluoroborates are a new pair of compounds, i.e., 1,3-dioxacycloalkanium tetrafluoroborate and 1,3-dioxane.The reaction is reversible and takes place by a transacetalization mechanism.
- Chalova, O. B.,Kurmaeva, E. S.,Kantor, E. A.,Kiladze, T. K.,Rakhmankulov, D. L.
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p. 1434 - 1437
(2007/10/02)
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- Elimination, Fragmentation, and Proton Transfer in 1,3-Dithianes and 1,3-Dithiolanes in the Gas Phase
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The gas-phase negative ion-molecule chemistry of 1,3-dithianes and 1,3-dithiolanes differs considerably from the in solution.When treated with anionic bases, 1,3-dithiane undergoes successive elimination reactions giving thiolates, in competition with deprotonation at the 2-carbon, which is the sole solution phase reaction channel.The appearence of the various product ions with changing base strength agrees with their calculated thermochemical onset.The gase-phase acidity of 1,3-dithiane is measurable if the elimination reaction is blocked by gem-dimethyl substitution at the 5 carbon.For 1,3-dithiolane, no deprotonation product is pbserved; even at thermochemical treshold, cycloreversion to RCS2- and ethylene occurs.This competes with successive elimination to thiolates, as with the six-membered ring.The differences between the gas phase and solution reactivities are rationalized in terms of counterion effects.
- Bartmess, John E.,Hays, Robert L.,Khatri, Hiralal N.,Misra, Raj N.,Wilson, Stephen R.
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p. 4746 - 4751
(2007/10/02)
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