29583-33-3Relevant academic research and scientific papers
Dual behavior of alcohols in iodine-catalyzed esterification under solvent-free reaction conditions
Jereb, Marjan,Vra?i?, Dejan,Zupan, Marko
scheme or table, p. 2347 - 2352 (2009/09/06)
The dual behavior phenomenon of alcohols in iodine-catalyzed esterification under solvent-free reaction conditions (SFRCs) is described; the governing factor is the stability of the carbonium ion generated from the alcohol; high concentration reaction conditions (HCRCs) or dilute solutions are much less suitable. In the case of benzylic alcohols, loss of optical activity was noted, whereas alkyl alcohols furnished a product with retention of stereochemistry.
Determination of geosmin and methylisoborneol in catfish tissue (Ictalurus punctatus) by microwave-assisted distillation-solid phase adsorbent trapping
Conte, Eric D.,Shen, Chun-Yi,Perschbacher, Peter W.,Miller, Dwight W.
, p. 829 - 835 (2007/10/03)
Methylisoborneol (MIB) and geosmin (GEO) are algal off-flavor compounds, which when present in catfish tissue create undesirable taste and odors in the prepared products. These undesirable taste and odor problems are not limited to catfish aquaculture. A procedure was developed for the determination of off-flavor compounds in channel catfish tissue that involves microwave radiation distillation with solid phase trapping. This is a modification of a microwave distillation-cold trapping procedure but without the need of a cryogen or a liquid-liquid extraction step. A channel catfish fillet sample is placed in a container located within a microwave oven. This container, which is directly connected to a thermostated condenser containing a solid phase adsorbent, is continually purged with argon gas. The trapped distillate components are eluted with ethyl acetate and then injected into a gas chromatograph-ion trap mass spectrometer for analysis. This technique offers a rapid and sensitive means of off-flavor analysis in fish tissue and improved recovery for MIB from 73 ± 3% (50 ppb) to 85 ± 5% (10 ppm) compared to 62 ± 6% for microwave-cold trap collection. The method detection limits are 1.7 and 1.1 ppb for MIB and GEO, respectively.
The Protonated Cyclopropane Route to Bicyclic Cations
Kirmse, Wolfgang,Streu, Joachim
, p. 515 - 521 (2007/10/02)
The protolytic cleavage of tricyclo2,6>hexane (3), tricyclo2,7>heptane (10), methyltricyclo2,7>heptanes (26), tricyclo2,8>octane (53), and tricyclo2,7>octane (58) in acetic acid and in aqueous dioxane has been investigated.Protonation occurred at a specific site (3, 36b,d, 58) or competitively at two sites (10, 26c, 53), depending on the stability of the incipient carbocations.Product distributions and label redistributions, where applicable, were in good to excellent agreement with previous solvolytic studies.We conclude that the protonated cyclopropane and ? routes are equivalent in generating bridged carbocations.Edge-protonated cyclopropanes play a minor role, if any, in product formation.Stereoselectivity appears to be an intrinsic property of the cationic intermediates, largely independent of the specific orientation of their counterions.
Norpinyl-Norbornyl Rearrangements: Bicycloheptane, 4-Methyl- and 6-Methylbicycloheptane Derivatives
Kirmse, Wolfgang,Siegfried, Rainer,Wroblowsky, Heinz-Juergen
, p. 1880 - 1896 (2007/10/02)
Norpinyl-norbornyl rearrangements have been induced by solvolysis of the 2-norpinyl nitrobenzoates 15b, c and by decomposition of norpinane-, 4-methylnorpinane-, and 6-methylnorpinane-2-diazonium ions (19, 49, 64, 65).No fragmentation to monocyclic cations was observed.The yield of norpinyl products was minimal in water (s processes).With 64 and 65, migration of the bridge trans to the leaving group predominated strongly.The rearrangements afforded exo-2- and endo-2-norbornyl products in comparable quantities.The exo/endo rates depended on the nucleophilicity of the solvent but were little effected by methyl substitution at the migrating carbon.We propose the 7-bridged norbornyl cation (21) as the endo-selective intermediate which rearranges to the exo-selective 6-bridged (or rapidly equilibrating) norbornyl cation (22, 23) in competition with solvent capture.Ion-pair collapse (cf. 15b) accentuates the endo-selectivity.However, ion pairing cannot be the only source of endo-2-norbornyl products, as shown by the deamination reactions in water.
