mississippichem

Are you talking about Michaelis-Menten kinetics? -K- being the Michaelis constant "K", or rate constant "k"?

There are organizations that rate the "impact factor" of various peer reviewed journals. I'm not sure if there is some universal method for determining impact factor, but I think it always involves the number of citations to that journal. Journals that are listed as having high impact factor are more likely to be sound resources generally speaking. I'm sure there are great journals that aren't often cited but when you're first beginning to look for references the highly cited ones are a good place to start.

Everything else is right. But If two hydroxyls remained, they would most likely be cis to each other. This is the electronic "trans-effect" and would be vanishingly small for fluorine. So really you're looking at an almost statistically insignificant excess cis over trans.

That's why all the other orbitals in methane are anti-bonding. Meaning that they are higher in energy than their constituent atomic orbitals. They decrease the stability of said compound.

Ionic bonds aren't really bonds. The preferred term is ionic interaction. Ionic interactions are just coulombic forces between positively and negatively charged ions. There is no real localized bond or shared electron pair. Though there can be a significant degree of ionic interaction between atoms that are already covalently bonded to each other. This comes from different effective nuclear charges which in turn leads to "unequal sharing" of electrons. Don't take that analogy too far though; unequal sharing really means that one of the atoms just gets more of the wave function localized around it. I'm not sure I understand this question... Low region? High region?

Can you support this rather bold assertion with evidence? Or should we just take your word for it?

Yes, but there are two electrons per single bond. This is an image of the [math]a_{1}[/math] and [math]t_2[/math] states for methane.

The silicon dioxide conglomerate particles are large enough and shaped so that they are prevented from being mobile enough to be a liquid and at the same time unable to lock into a rigid crystal lattice to form a true "solid" with a defined melting temperature. Check my blog, I had a short entry about this with a link to a relevant article.

Yes. Sometimes there are ionic forces to deal with, but bond enthalpy (the energy of the bond) is by far the determining factor for the energy required to break the bond.

Molecular orbitals are the result of a linear combination of atomic orbitals. If the bond is formed homolytically (by combination of H and C radicals), then an electron in a 1s hydrogen orbital spin pairs with an electron in a 2s carbon orbital to form singly degenerate orbital with [math]a_{1}[/math] symmetry. This [math] 1s-2s\sigma [/math] orbital is lower in energy than either of the atomic orbitals it came from. This is not the case for all molecular orbitals though. Methane for example has higher energy orbitals,[math] \sigma^{*}(a_{1}^{*})[/math], and [math] \pi^{*}(t_{2}^{*})[/math] that are higher in energy than the corresponding atomic orbitals. These orbitals are unoccupied in the ground state and are anti-bonding.

I'm sure fundamental arguments exist. However, I don't think it needs to go that far. It has been presented in this thread that the idea of "corpuscular electrons" and therefore the model that you present are not reconcilable with the huge body of spectroscopic, and other, evidence that exists. Hyperfine splitting, I=0 nuclei, observed angular momentum, [not to mention the how the "G free-fall" model will predictably botch all currently accepted theories of chemical bonding (especially ligand field theory).]; all the quantities and behaviors predicted by this model are out of line with those experiments. Until that can be reconciled, further delving into fundamental arguments is futile and in my opinion non-rigorous. A proposed model must first fall in line with accepted experimental evidence. Period. I'm not trying to be dogmatic, that's just the way science is conducted.

So do software companies and corporations pay "white-hat" hackers to try and crack their stuff as a preemptive security test? This might be a stupid question...I know nothing of the sort.

I will confirm your structure for the [ES] complex binding site. I'm looking in a biochem textbook and it is spot on. I'm no glyco-chemist [not by a longshot] but the mechanism you have concocted seems fairly airtight. I don't see any obvious problems. Resonance, sterics, and order all seem reasonable. Though i'm not sure how that last hydration from Glu 238 is enatioselective. I've no doubt that it always gives the [math]\alpha[/math]-anomer, I just don't know how. Is it just a "Glu-238-is-just-on-that-side-of the ring" phenomenon?

Yeah, sorry! cyclopropanation! Duh ! I made that post 6 beers deep. I should stop that. I guess that makes a lot more sense that this Rhodium catalyst does that. Sci-finder gives a load of references. I kept typing in "enatioselective rhodium catalyzed expoxidation" and to my dismay it couldn't find any relevant references. I know why now. [4+3] eh? I'm not familiar with such, but I am with Cope rearrangements. I'll look into it. It makes sense for a Rh(II) bimetallic though since cyclic voltammetry shows that similar complexes tend to undergo a 1 electron reversible oxidation couple. (I did some electrochem work with Ru, Rh, and Os bimetallic aromatic nitrogen heterocycle complexes; which electronically, should behave similarly to your catalyst).

Very true, if electrons had trajectories then the EPR spectrometer at my school would need to be able to time resolve in order to get any meaningful hyperfine splitting. It doesn't time resolve, and I got some beautiful hyperfine splitting just yesterday.

In step 5, is your rhodium catalyst a chiral [ce]Rh_{2}(DOSP)_{4}[/ce] type species? I've never seen epoxidations with those catalysts, but I have seen enatioselective C-C addition over a double bond also in the presence of a terminal azo-group with that same rhodium species. New enatioselctive epoxidations are always nice to see..."Sharpless" assymetric epoxidations are nice but the tetrakisisopropyltitanium(IV) reagent can be a pain to filter out. By the way, nice microwave assisted allyl migration heading into 15. I wonder if that proceeds as a [2+2] "pseudo-concerted" followed by a C-O cleavage? It would seem typical of microwave rearrangements but I'm just speculating.

If you have an idea for improving a synthesis, that's fine. I just wanted to start a thread for general synthetic discussion; whatever that may encompass. Feel free to post your own syntheses, not just drugs either; anything really. I just posted this one to start things off. No this isn't the industrial synthesis. It's the second patent filed for the synthesis of the drug at the lab scale. I'm willing to bet that the industrial synthesis starts at the pyrazole though.

I figured I would start a thread for us chemistry folks to post some reaction schemes and discuss synthesis design, as well as relevant laboratory techniques. I'll start things off with the total synthesis of Sildenafil [trade name "Viagra"]. The drug is administered orally as the ammonium-citrate salt. This is the lab scale synthesis and is covered in detail in Bioinorganic and Medicinal Chemistry Letters Vol. 6. This scheme is brought to you courtesy of: www.ch.ic.ac.uk Notice the sulfonamide that shows up in the last step. I chose this synthesis because of the simple functional group transformations that lead to a highly marketable drug. I also like the beta-dicarbonyl+hydrazine step to give the pyrazole; A clever variation on the typical ketone -> hydrazone reaction.

What's with all these pointless spam-bots? I thought the goal of spammers was to go around the internet selling useless products to confused people on ill-moderated forums. If you're going to be a spammer...at least try to sell us some homeopathic remedies or something else mildly entertaining.

I'm fairly sure n-butyl lithium will reduce them all the way to the thiol. Though I'm not sure what affect the amino nitrogen has on that.

Ask the psychic if he could speak to your dead aunt "Edna". When he starts to speak with "Edna", inform him that you don't have a dead aunt "Edna". Please take down a transcript of the conversation or record it. You might create a skeptical classic. Or ask the psychic to give you stock market advice. He will try to dodge the question because he knows he will be wrong. Even better yet. Present the psychic with a complicated math problem. If he can't find the determinant of a 5x5 matrix, he can't predict the future. If you know the answer to the question he would've just been able to envision you giving him the right answer five minutes from then.

Create a new universe without conservation laws!

Remember that the motion of an body can be separated into its vector components. Namely x, and y components; and its often convenient to set the y-axis normal [perpendicular] to the ground since gravity pulls in that direction. So your object with [math]\theta=0[/math] has an x-velocity component of 0. Your object released at [math] |\theta|>0[/math] has some velocity in the x-direction, but is there anything different about it's y-component when compared to the other body? Think carefully.

I would be way more worried about protecting those sulfones from reduction. Purplepeopleether, whatever you do, you need a very non- reducing base as those sulfones are very easy to reduce to sulfoxides or thiols.

No. The more certain you are of an electron's momentum, the less certain you are of it's position. You can know the position of an electron quite well, but you'll be very uncertain of it's momentum.