mississippichem

Though evidently you haven't lost interest in reading them. I've lost interest in people trying to get free synthetic help from me while at the same time refusing to divulge their intent. I'm also tired o people claiming that curing cancer is easy. I worked in an anti-cancer lab for a year. As an MD, you should know that curing cancer is not easy. If you think it is, then I believe we should make med-schools more difficult, because quite frankly that scares the hell out of me. You are clearly ignorant of all things chemical. Next time you need synthetic help, consult a childrens' chemistry set because that seems to be about your level of chemical cognition. The fact that you call yourself an MD/PhD is laughable. I'm an undergrad and found the azoxymethane prep in about five minutes. Your PhD must be in theater, because you are terrible at acting like a chemist. Good day sir.

Because [ce] CF_{3}^{-} [/ce] or [ce] CCl_{3}^{-}[/ce] are such a good leaving groups when next to carbonyls and because keto-enol tautomerization is very fast. Substitution by the hypohalite would be competing with the [imath] S_{N}2 [/imath] you speak of. Becuse of the carbonyl, the individual halide molecules would be poor leaving groups in this scenario anyway.

I would make it to where algebra starts earlier so that students could get calculus earlier. Part of the problem with science education in the US is that we can't learn much physics without calculus, and calculus is usually one of the last math courses students take in high school. If they could get to calculus by their first year of highschool, then they could dive into a lot more physics/chemistry before college. Our problem is, we don't teach kids about the language of algebraic manipulation while their brains are still forming those language connections. Teach them early, make it as natural as talking or writing. Also, I would do away with the "general science" curriculum in elementary and middle schools. It is a useless waste of time. Every year, the students would take a different specific science. 9 year old children may not understand deriving the equations of motion, but they can understand how to do simple [math]\sum \vec {F} = m \vec {a} [/math] problems or gram/mole conversions. Think if we had kids that new the basics of the laws of motion by high school! That way, we could offer more specialized science classes in high school like electronics, organic chemistry, or genetics (after taking stats, heh). I agree here. who cares what the author's purpose is? It always bothered me that English teachers speculate about unknowable intent and treat it as if it isn't just speculative opinion. Did you know William Faulkner!? How then can you know what he intended in the book? What we need are students who know how to debate, persuade, argue gracefully, and defend their ideas. Literature has it's place, and I like Faulkner a lot; but why didn't I get more training in technical writing (which is what makes the world go 'round). Even future business students will need to know how write a proposal with quantitative arguments...You should finance my endeavor because our earnings potential is "X", last year we showed "Y" increase in profit margins as our debt to assets ratio dropped to "Z". Interesting thread Cap'n.

Biochemistry is the best way to have a fundamental understanding of the mechanics behind biology. You can memorize the citric acid cycle, or you can learn some chemistry knowledge to "re-figure it out" at any point.

The electromagnetic force that holds ions together in salt, or atoms together in sand is WAY stronger than gravity. I'm comparing apples to oranges a bit here, but the gravitational constant is: [math] 6.67 \times 10^{-11} [/math] while the Coloumb constant (the proportionality constant that goes into calculating the force between two charges) is [math] 8.99 \times 10^{9} [/math]. So let's do a little calculation: The magnitude of gravitational force is given by: [math] F= G \frac{m_{1}m_{2}}{r^{2}} \hat{r} [/math] "G" is the gravitational constant, the two "m's" are the masses in question, r is the radial distance between the two masses and the "r" with the funny looking hat equals 1 (don't ask, ). So the gravitational force between two sodium atoms (one nanometer apart) is: [math]F = (6.67 \times 10^{-11} N \cdot m^{2} \cdot kg^{-2}) \frac {(3.82 \times 10^{-26} kg)(3.82 \times 10^{-26} kg)}{(1 \times 10^{-9} m)^{2}} [/math]...I get...[math] 9.73 \times 10^{-44} N [/math]. If you don't have a feel for Newtons, let me tell you that is a vanishingly small force. Alright, so now lets look at the magnitude of electric repulsion between two positively charged sodium atoms (at one nanometer apart): We will use Coloumb's Law. [math] F = k \frac {q_{1}q_{2}}{r^{2}} \hat {r} [/math] Everything is the same here, except that "k" is now the Coloumb constant and the "q's" are charges instead of massses. The net charge on a sodium ion is [math] 1.60 \times 10^{-19} C [/math], so... [math] F = (8.99 \times 10^{9} N \cdot m^{2} \cdot C^{-2}) \frac {(1.60 \times 10^{-19} C)(1.60 \times 10^{-19} C)}{(1 \times 10^{-9} m)^{2}} [/math]...here I get...[math] 2.3 \times 10^{-10} N [/math]. That is about [math] 2 \times 10^{33} [/math] times more force than we saw in the gravity calculation! Like I said, I'm comparing mass to charge, and therefore apples to oranges but you should still be able to see that gravitational interactions between things on the molecular scale can't even hold a candle to electrostatic interactions at the molecular scale. That's why chemists can safely ignore gravity, and why the salt crystal stays intact when being dropped onto another salt crystal. Even though the calculation would be with the Earth's gravity, electrostatics still win out.

Are you suggesting synthetically altering keratin to make it more lipophilic? As in adding extra alkyl-groups? Otherwise keratin is already as lipohilic as it can be. I'm not sure I understand your meaning.

This is wild speculation, but perhaps angels are present in the stories to provide contrast. Can't remember where, but somewhere in the Bible it is mentioned that the angels covet the mortal lives of the humans and are also jealous that God would send his son to die for the filthy sinning humans. Angels get the fortune of having perfect bodies and basically no problems, whereas humans have to deal with the struggles of life on Earth but having finite lives can appreciate the concept of time and God's forgiveness. Having angles present in the mythology highlight's a god's love for imperfect humans. Angels seem like they are higher in the rankings but many stories in the Bible highlight the fact that god uses them to serve humans by sending messages, protecting, and comforting. Are angels supposed to have free will in the Christian Tradition? Anyone know?

Horza, your organo-centrism is showing . Maybe they will be useful intermediates on the way to smart base metal materials . Just kidding, interesting article. I gotta take my opportunities to poke at you organic guys.

I agree, the arXiv has quite a few interesting papers in their "quantitative biology" section. Something I didn't even know existed until I saw it there.

I know a few physicists that think they understand mass-spec fragmentation patterns and molecular dynamics . Sorry, had to take up for the home team. Forgive my post quote necromancy. And yes, I know a good bit of QM that is applicable but I don't have the slightest clue about anything with the words "field theory" in it. We chemists blissfully neglect gravity as well, except for the fact that it keeps liquids in beakers.

I'm glad you mentioned this. I think people have trouble understanding that bonds are not confined and the orbitals of a molecule exist as a dynamic, interdependent set. You can't just excite one without exciting the whole set. Many of these folks are victims of the "solar system" atomic model which also doesn't lend itself to any kind of intuition about bond angles. Bah humbug. Lemur: this answers your question about the tunneling of electrons through the nucleus and why it matters.

For that we have molecular dynamics, density functional theory (DFT), and a host of other molecular modeling techniques. We can also observe the structures of molecules with pretty much any kind of spectroscopy. We chemists have gotten really good (shameless self glorification ) at that since the advent of COSY 2-dimensional nuclear magnetic resonance spectroscopy. Molecules most definitely have moments of inertia. As they have mass and can undergo rotational motion. The entire molecule can rotate or an atom or group of atoms can rotate about the axis of a bond. Just like in physics, in chemistry we can interchange classical and quantum treatments for systems. it just depends on what we are interested in, what degree of approximation we are willing to accept, and what the scale of the system is. A one molecule system gets treated very differently than [math] 10^23 [/math] molecules. Some people even treat a single protein as a classical object because some of them have molecular weights in the 100,000's. I don't think we have to worry about an enormous hemoglobin molecule tunneling through a cell membrane. But we do have to worry about an electron pair tunneling through the nitrogen nucleus in an ammonia molecule, if we are interested in molecular geometry.

All those types of spectroscopy that I mentioned above. They wouldn't work in the way they do without spring-like, fixed connectivity bonds. This is why ionic solids don't show up on FTIR for the most part. Do you mean in reference to average bonds angles or connectivity? Both answers are lengthy and probably require a new thread. I can tell you that we confirm molecular structures precisely by growing crystals and subjecting them to neutron, electron, and x-ray diffraction experiments. They short, psuedo-classical answer on bond angles is that electron pairs repel each other, and will seek a geometry that minimizes their repulsion interaction. The good answer involves group theory, and symmetry considerations and requires a new thread.

Chemical bonds are not at all rigid. In fact they act somewhat spring-like, a spring constant can even be calculated for a given bond. Atoms on the ends of bonds can rotate, vibrate, bend, or undergo translational motion. The vibration is quantized much like the energy levels of electrons [except these vibrational levels are very close together]. Bonds can even be broken by exciting them to very high vibrational levels. We can use spectroscopy like Fourier-Transform Infrared or Raman Spectroscopy to study the various vibrations, translations, rotations, and bends as we can excite molecules to different vibrational levels by firing radiation at them and observing which frequencies they absorb. The shape of molecules is always changing with this motion, but the average bond angles and connectivity remain the same.

It's a bit difficult to deterministically say how many electrons are being shared, remember we're dealing electron wave/particles. But certain approximation techniques show that the two oxygen atoms share 4 electrons. The two unpaired electrons can almost never be shared because they are in anti-bonding orbitals. The sharing of those two electrons is rare because that requires a parity violation, a rule that comes out of group theory used in quantum chemistry. If there is an available proton around, [ce] H^{+} [/ce], the superoxide ion can grab that proton and accept another electron to form the peroxide ion: [ce] HOO^{-} [/ce] which really contains the [ce] OO^{2-} [/ce] fragment. All fermions, this includes electrons, have spin +1/2 or -1/2 [the sign choice is arbitrary]. Every orbital can accommodate two electrons, and each electron must have a unique set of quantum numbers. So electrons are spin paired if they both reside in the same orbital and have opposite spins. Glad to know someone out there in cyberspace is listening to my rants. John Cuthber: Physicists say a diatomic molecule is a molecule with one too many atoms. Physical chemists say that an asymmetric diatomic is a molecule with one too few n-fold axes of rotation . Lemur: Unfortunately whenever you have a molecule that is very asymmetric and with orbital energies or effective nuclear charges that are very different, the picture gets pretty complicated. I would be doing you a disservice by trying to explain it without evoking the math of group theory and overlap integrals. Deriving the orbital configurations for these molecules is laborious even for the experienced. In real life, you can just let Waveunction Spartan software do the work for you.

A decent guess. This used to confuse me my freshmen year. You actually end up with two uncharged O atoms [diradicals, two unparied electrons]. Each has 8 electrons, as the [ce] O_{2} [/ce] they came from had 16. This is actually pretty hard to do though, unless you have substrate to react with the free O atoms. as an [ce] O_{2} [/ce] molecule would be more likely to just gain an electron from somewhere else to form a superoxide radical anion: [ce] O_{2} \cdot ^{-} [/ce], a paramagnetic, 17 electron species. Some have postulated that this is the first step in the combustion of organic molecules in air. [ce] O_{2} [/ce] can have some counter intuitive chemistry as it exists as a diradical in the ground state [two unparied electrons]. Molecular oxygen would rather spin pair one of its radicals than split into two more diradicals.

I'm with hypervalent_iodine here. The signals you are giving us are not reminiscent of what a trained chemist would be giving us. I don't think you are a chemist either. If you really are, then I am sorry. If you would like to defend your honor, please start a thread in the speculations forum and pitch us your idea about anti-cancer drugs. If we find that your proposed mode of action appears to be legitimate, then I will personally private message you an azoxymethane prep that I've already drawn in ChemDraw and have cited from the literature. If you decide to pitch us your proposal, I will expect to see professionally rendered structures drawn, some cited sources, and any relevant quantitative data/derivations. All this is par for the course in the professional chemistry world. Yes, we are more hard nose than the physicists. This should be normal, and easily done for a PhD chemist.

The toxicity claims are true. Iodomethane is quite toxic. But read this, evidently the risk of ingesting iodomethane from produce is low: California Environmental Protection Agency, August 2009. Read the full paper at: www.cdpr.ca.gov/docs/risk/mei/mei_vol3_ef.pdf I'm no toxicologist, but I doubt you have much to worry about. Don't be suckered in by the "Organic Food" mongers.

Animals have many custom fit receptors that only bind to certain molecular shapes or functional groups. For example, the thiol group, [ce] -SH [/ce], is especially smelly to humans. So this molecule: 2-aminothiophenol, has a very strong, rotten egg/dead animal smell. Presumably because of the[ce] -SH [/ce] group there, but the [ce] C_{6}H_{5}NH_{2} [/ce] [aniline] group has also been known to be smelly so I'm speculating a bit here. I have smelled this compound though, very gross.

How do you deal with the enormous amount of observational evidence that supports relativity? Even the ionization energy trend of heavy d-block elements is consistent with Lorentz transformations and special relativity due to the relativistic mass of a very fast electron. I'm a chemistry person, I'm sure the physicists around here can come up with a much better example.

Here are some lectures I found on Youtube. They cover the basic concepts of electronic structure of molecules. This will be of interest to anyone interested in physical chemistry/molecular physics. The first lecture covers the Born-Oppenheimer Approximation and he later moves on to Ab Initio, Hartree-Fock, and DFT methods. Prerequisite knowledge includes, a basic QM or Q-physical chem course, and some differential equations/multivariable calculus. I find the lectures quite easy to understand considering the material at hand. I imagine this course is the equivalent of a first year grad level quantum chemistry course. The guy teaching these lectures, Jack Simmons, is quite a physical chemistry heavy weight; some of his publications can be found here. I wish he would learn some LaTex though, his equations can be a bit troublesome to read. I used his Hartree-Fock lecture to clear up some confusion I was having and it helped. Have fun.

Judging by the quality of our roads I imagine that only entropically favored processes are allowed here, which means all endothermic exergonic reactions are legal.

Please elaborate further on this statement. I want to hear your "easy" solution. I know of a few major pharma companies spend over 50% of their R&D budgets on combinatorial synthesis for anti-cancer. What do you know that the rest of us chemistry people don't?

But that energy started out in the bonding orbitals of nutrient molecules so its not really the same thing as relativistic matter-energy equivalence. Its just converting chemical potential energy into another chemical form, harvesting energy from the exergonic reactions that take place along the way.

Read about boiling point elevation and colligative properties.