Khan academy isn't helping. Klein isn't really helping, not to the extent my prof wants things. I can't understand her classnotes anymore. I've reached out to classmates and nothing has really bloomed in terms of a helpful relationship or study group. Everyone is stingy with their answers or leaves you on "Read". I've probably spent 800 dollars on tutoring this semester. I'm somewhere between a C and B in her class (55%, after curving is considered, I'm more like a 78%) but unless I get some help soon, I WILL fail this next midterm, I WILL fail the final... I cannot afford anymore tutoring and I just need some better resources to know WHAT to study... because everything that I am googling (our prof mocks us for using google, says we don't need "university" if we go to "google u")... I'm just panicking. I need some help, man. I just need to know "what" to study to learn synthesis. She said she's going to quiz us on reaction coordinate diagrams, "to scale", AND have us construct our initial molecules from NMR. I don't know the first thing about NMR and neither do my classmates, really. I just don't know where to go for help at this point. I will attend her office hours, too. If there's anyone who can point me in a direction of useful practice with some answers or something, that would really be helpful...
My attempt (epoxide opening --> E1 --> tautomerization):
https://preview.redd.it/wfoo2mrblh381.jpg?width=1539&format=pjpg&auto=webp&s=d307b742fd266c9502e4c9d9dbef41241a9d6b2d
Solution (epoxide opening --> rearrangement):
https://preview.redd.it/2ays0k0nlh381.png?width=1156&format=png&auto=webp&s=a72a7356e8c9e03b7d2039049dae2f78e6d4dd43
May I ask what are the problems with my mechanism, which parts seems unreasonable?
https://preview.redd.it/7ca37puwbg381.png?width=1274&format=png&auto=webp&s=a7969af348a33d89ffa811530caf012cc9179fb9
From this photo, after halohydrin is formed, NaOH is added to deprotonate the OH and SN2 happens to form the epoxide, but won't the NaOH continue to attack the epoxide and open it to form trans-diol? Thanks
Need advice, please. Is it really necessary to know reac of ethers/epoxides or can I still understand the reactions of Aldehydes and other reactions?? Any 2021 person plz help?
Anything helps
Journal of the American Chemical SocietyDOI: 10.1021/jacs.1c00659
Aleksandra Potrząsaj, Mateusz Musiejuk, Wojciech Chaadaj, Maciej Giedyk, and Dorota Gryko
https://ift.tt/3fMCdlm
I haven't had any ill side effects using mupirocin 2% as a topical antibiotic ointment for an open wound. But epoxides are so reactive under biological conditions. How is this fine to being given oral and IV?
The busting open of that epoxide ring is not an enzymic process. Any nucleophile attack will do - no enzymes required, which means it lacks that tight(er) regulation and a multitude completely structures. You could end up with totally different products destroying, or not destroying, structural integrity of cell walls and glycogen depending on what you ate. It's supposed to only be incorporated into bacteria, but hundreds of different conversations could occur.
Like chloride, hydroxide, or methylamine (obviously) will give totally different functional groups on the product with an epoxide precursor. Someone who loves onions will have more hydrosulfide in them making something else again for example, and that may not have been studied.
Not like it's something that is guaranteed to only affect bacteria. You don't know for sure. It showed efficacy for some infections, but just because it was safe throughout the clinical trial doesn't mean it didn't fuck up an allele that is needed for programmed cell death (which would hit you like 30 years later).
That glucornated fatty acid looks like something bacteria would love, but who knows what molecule your gonna get that'll jam up the central dogma and it selectivity to bacteria would stay no matter what. I'm sure mostly chloride and hydroxide nucleophiles end up in the product, but who knows
I don't know why but I can't figure out what happens to the epoxide. Is isosafrole glycol formed? I have a suspicion the answer is right in front of my face but I have no idea.
In the buffered reaction there's no isosaf. monoformyl glycol right?
Producing polyesters with high molecular weight ( M n ) through ring-opening copolymerization (ROCOP) of epoxides with cyclic anhydrides remains a major challenge. Herein, we communicate a metal-free, highly active, and high thermoresistance system for the ROCOP of epoxides with cyclic anhydrides to prepare polyesters (13 examples). The organoboron catalysts can endure a reaction temperature as high as 180 Β°C for the ROCOP of cyclohexane oxide (CHO) with phthalic anhydride (PA) without the observation of any side reactions. The average M n of the produced poly(CHO- alt -PA) climbed to 94.5 kDa with low polydispersity ( Γ = 1.19). In addition, an unprecedented turnover number of 9900, equivalent to an efficiency of 7.4 kg of polyester/g of catalyst, was achieved at a feed ratio of CHO/PA/catalyst = 20000:10000:1 at 150 Β°C. Kinetic studies, crystal structure analysis, 11 B NMR spectra, and DFT calculations provided mechanistic justification for the effectiveness of the catalyst system.
https://ift.tt/3564xcd
The first catalytic asymmetric multiple vinylogous addition reactions initiated by Meinwald rearrangement of vinyl epoxides were realized by employing chiral N,Nβ²-dioxide/ScIII complexes as catalysts. Direct vinylogous additions via dienolates of Ξ²,Ξ³-unsaturated aldehydes were realized. A series of chiral Ξ±,Ξ²-unsaturated aldehydes and spiro-cyclohexene indolinones were synthesized in good yields with excellent stereoselectivity.
Abstract
The first catalytic asymmetric multiple vinylogous addition reactions initiated by Meinwald rearrangement of vinyl epoxides were realized by employing chiral N,Nβ²-dioxide/ScIII complex catalysts. The vinyl epoxides, as masked Ξ²,Ξ³-unsaturated aldehydes, via direct vinylogous additions with isatins, 2-alkenoylpyridines or methyleneindolinones, provided a facile and efficient way for the synthesis of chiral 3-hydroxy-3-substituted oxindoles, Ξ±,Ξ²-unsaturated aldehydes and spiro-cyclohexene indolinones, respectively with high efficiency and stereoselectivity. The control experiments and kinetic studies revealed that the Lewis acid acted as dual-tasking catalyst, controlling the initial rearrangement to match subsequent enantioselective vinylogous addition reactions. A catalytic cycle with a possible transition model was proposed to illustrate the reaction mechanism.
https://ift.tt/3cYABng
Hello. Say I have (E)-2-pentene and I treat it with RCO3H to get 2,3-epoxypentane. If I were then to react this epoxide with a strong nucleophile such as NaCN, would I get a mixture of products, one with the hydroxyl on carbon 3 and one with the hydroxyl on carbon 2 (ignoring stereochemistry)?
The direct copolymerization of epoxides with pβtosyl isocyanate was achieved in the presence of trialkylborane and polyurethanes could be obtained without the formation of cyclic isocyanurate, in high linear/cyclic and urethane/imidocarbonate selectivity. The reported method provides access to the modification of properties of other polymers, especially aliphatic polycarbonates generated under the same conditions.
Abstract
The direct copolymerization of pβtosyl isocyanate (TSI) with epoxides, initiated by onium salts in the presence of trialkylborane, to produce polyurethanes is reported. The rate of copolymerization and the (regio)selectivity were investigated in relation to the trialkylborane and the initiator used. Under optimized conditions such copolymerizations have been successfully performed for a wide range of epoxides, including ethylene oxide, propylene oxide, 1βoctene oxide, cyclohexene oxide, and allyl glycidyl ether. These copolymerizations afford a new category of polyurethanes, clear of side products such as cyclic oxazolidinone, isocyanurate, and poly(isocyanate) linkages. The experimental conditions used in this work are compatible with those for the organocatalytic (co)polymerization of other oxygenated monomers and CO2, holding the potential for their terpolymerization with pβtosyl isocyanate and the development of new materials with unprecedented properties.
https://ift.tt/35AGaV9
The first catalytic asymmetric multiple vinylogous addition reactions initiated by Meinwald rearrangement of vinyl epoxides were realized by employing chiral N,Nβ²βdioxide/Sc(III) complex catalysts. The vinyl epoxides, as masked Ξ²,Ξ³βunsaturated aldehydes, via direct vinylogous additions with isatins, 2βalkenoylpyridines or methyleneindolinones, provided a facile and efficient way for the synthesis of chiral 3βhydroxyβ3βsubstituted oxindoles, Ξ±,Ξ²βunsaturated aldehydes and spiroβcyclohexene indolinones, respectively with high efficiency and stereoselectivity. The control experiments and kinetic studies revealed that the Lewis acid acted as dualβtasking catalyst, controlling the initial rearrangement to match subsequent enantioselective vinylogous addition reactions. A catalytic cycle with a possible transition model was proposed to illustrate the reaction mechanism.
https://ift.tt/3cYABng
Hey guys can anyone help me with this
https://preview.redd.it/8r3wesszal361.jpg?width=1440&format=pjpg&auto=webp&s=77be3639553c0106a3872e1776f03ada5f62e114
