112836-13-2Relevant articles and documents
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 (1996)
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.
-
Berson,Ben-Efraim
, p. 4094,4099 (1959)
-
Akhtar,Jackson
, p. 813 (1972)
Lee,Wong
, p. 2752 (1964)
Brown et al.
, p. 5536,5537 (1970)
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.
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.