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Everything posted by Horza2002

  1. I'm not 100% sure, but these are some ideas that I came up with: Under the acidic conditions you mentioned, it is possible that the carboxylic acid and one of the hydroxy groups in the compound are undergoing an esterifcation reaction so that you end up with a polymer of ursodeoxychloic acid. Under the basic conditions, you will deprotonate the carboxylic acid to give the conjugate salt of the compound. Its possible, because ursodeoxychloic acid is very hydrophobic, that the salt forms an emulsion type structure in the water; hence appearign as a gel
  2. You can't predict how an element will be toxic given its electron configuration.... Aresenic is toxic because it mimics phosphorous (arsenic bonds are much weaker the phosphorus bonds so they hydroylse to quickly before the cell can use them) One of the many ways lead is toxic is because it is sulphur-philic and so interferes with the disulphide bridges in proteins. In terms of the mercury question, organomercury molecules have a better bioavalibility than inorganic mercury (i.e. its easy for the body cells to absorb it and is therefore more dangerous). The oxidations state of the mercury will also be important (as is the case for many metals)
  3. If you actually wanted to do this reaction, I would say the best way to make a cyclobutane/ene ring would be a photoinduced [2+2] reaction....trying to get that Grignard to cyclise before it polymerise might be a little tricky.
  4. Well, the carbonyl of an amino acid will not undergo a Wittig reaction...you need an aldehyde or a ketone not an ester, amide or carboxylic acid. And for the record, the alpha proton will definatly racemise under Wittig conditions....people in my group have used similar things and managed to convert an enantiomerically pure compound into a racemate.
  5. As Mississippichem has already said, it will really depend on what your trying to do. If you want to analyse X-ray structures, then something like Pymol is pretty good...although is not exactly friendly to new users. For modeling small molecules, there is RasMol...but I have never really been impressed with it...
  6. Mitsunobu should probably be up there.....that reaction has been very useful in completely converting one alcohol enatiomer to the other...very useful
  7. Do you mean how to make haloforms (as in chloroform, bromoform, etc) or how to do the haloform reaction? The haloform reaction converts a methyl ketone into a carboxylic acid using Iodine and hydroxide. The side product of this reaction is iodoform. Bromoform and clhloroform are noth side product in the Appel reaction in which an alcohol is converted to a halide using triphenylphosphine or CCl4 or CBr4.
  8. As Hyper says, you would simply have to do a extra work to get the basics as well. I would recomend the book "Organic Chemistry" by Clayden, Greeves, Warren and Wothers. This book goes from the basics (such as what are bonds?, pKa) all the way upto assymetric catalysis. It does take a bit of reading to get your head around though...but thats chemistry
  9. Are you sure about the product of the first step? In your starting material, you don't have any carbons with hydrogens bound to then (you have the ketone and iminie carbons), but in the product you do....it is possible a rearrangement/migration goes on, but not completely sure.
  10. The alkalie metals are called that because when they react with water, they give an alkaline solution. Theres no real easy way to do this, you just need to sit down and learn them.
  11. Are you wanting to reduce the amount of cycloocta-1,5-diene in your sample, or are you wanting to reduce the double bonds to single bonds? I'm assuming the former rather than the latter seeing as you've given ppm. You could always try a distillation...the components of the mixture you have all seem to have different boiling points. Alternatively, you could just extract the water layer with an organic solvent, say ethyl acetate. The COD will not really be soluble in water so you could get the majority of it out that way.
  12. http://en.wikipedia.org/wiki/Surfactant Then go down to classissification section, theres a list of some there.
  13. What exactly have you plotted here? And no, where the line crosses the y-axis tells you the absorbance of your mixture when there is none of your solute present. What I expected to happen, was that you have an unknown concentration of x which you wished to know the concetration of. So you would have made up some samples of known concentrations of x and then measured the absorbance (which should be your blue points). They should then give you a nice straight line as the absorbance will be depending on the concentration of x. So now that you have your graph and straight line, you need to measure the absorbance of the unknown concentration of x. Once you have that, you will then be able to use you straight line to correlate the absorbance on the y-axis) to a concentration (on the x-axis). Does that help?
  14. As you have already staed, the composition of the air is mainly nitrogren and oxygen with a sevreal other gases all mixed in (water vapour, carbon dioxide and argon). IN principle, every compound should be able to exist as a gas...howeve, this is not always the case. Some compounds decompose upon heating (decarboyxylation is beta keto acids is a common example) and so they never get into the gas phase. In addition to the gases that are all mixed up in the air, there are also a lot of particles that are just suspended in the air because they are so light. Bacterial spores are one, dust, pollution all sorts of things can become spread through the air. As for smell, well it could be either of the two processes so far mentioned. If what you are smelling is a gas, then its simple just part of the air that you inhale. However, you can also inhale the small particles that are suspended in the air. I assume that is how you can smell things in the air that are not actually in the gas phase. So for your example of rust smelling like blood (because of the iron it contains) is because there are small particles of rust floating around the air which you inhale and then smell
  15. You would normal make 5 samples of known concentration to run at get a straight line. You could then determine the AA for your unknown sample by extrapolating from the line you just drew
  16. Ok sorry, I didn't make that clear. Molecules typically have four "types" of energy: Translational - the general movement in 3D space of a molecule Rotational - the tumbling motion of a molecule through space Vibrational - the bending, stretching etc of bonds Electronic - moving the electrons between orbitals In order to make the orbitals bigger, you would need to excite an electron into a higher orbital - that is electronic "energy" and normally requires photons of at least UV frequency. IR photons can be absorbed by molecules that result in changes in the vibrational state of the system...this does not change which orbitals are occupied. Mississippichem has said the bands are like springs, they move more when they're hot.
  17. You also need to be careful on what you are using to define the atomic radii; there are several different methods Van der Waals radii - half the minimum distance between the nuclei of two atoms of the element that are not bound to the same molecule Covalent radii - the radius of an atom when covalently bound to another atom Metallic radii - the distance between adjacent metal atoms when metal bounding is involved Ionic radii - the distance between certain ions involved in the bonding of a ionic compound Depending on which method you are using to define the atomic radii will greatly affect the result you get. Obviously, noble gases can't use covalent, metallic or ionic radii. As you go down the halogen group, they do get larger as a resulting of filling orbitals further from the nucleus...however, they are still the smallest of that period.
  18. In order to get an electron to "expand", you would need to excite it into a higher energy orbtial (typically, the higher the orbital energy, the further it is from the nucleus). Heat is infar red photons which posses energy relating to their frequency (E=hv). If you calculate the energy that infa red protons have, then it is not enough to excite electrons into higher energy orbitals. For almost all bonds, you need UV light to cause excitation. Infar red radiation, however, can be absorbed by molecules which results in their bonds vibrating, stretching, bending, etc and is the basis of IR spectroscopy. In terms of a metal, this would translate into the metal atoms vibrating and moving around faster which then corresponds to increase in volume.
  19. Yes sorry, maybe I didn't make it clear in my post. What ever you use to measure the sample would depend on the techique you were going to use. Dioxane is useful for NMR because all the protons are equivalent, but it would be useless for UV.
  20. I'm guessing that would depend on what you wanted them to do. O and for the international people here, Wales is part of the UK.
  21. As Mississippichem has said, oxidation is an unforuntate terminolgy. It is used, however, because when the process was discovered, all the known processes involved oxygen. The first studies were metal oxides. Examples of oxidation/reduction (aka redox) reactions that don't involve oxygen and metal-metal reactions. Some metal ions are capable of reducing/oxidising other metal ions. This depends on the oxidation potential of the individual metal ions and also the spin state of that ion.
  22. I have no doubt at all that if somebody high up (president, PM...emperor) said "I want X, Y, Z to happen, heres the money" then X Y and Z will happen reasonably quickly. If you give enough people enough time, then they will be able to do almost anything. I think the major problem is that there are so many potential areas and ideas that could be developed, people up top don't really know what to pick. If you take the idea of solar technology, then you have those two ideas along with "solar road surfaces", "orbital solar power stations", "solar windows" and more to pick from...which ones do you pick to say make them happen? With respect to those two you outlined, I quiet like the idea of the "leaf". It could potentially prove to be an efficient method in which to produce hydrogen ever replaces oil as a fuel.
  23. Why would they need to do it publicaly? They could just keep his body in a secret location for the devoted follower who they beleive have earned the right to go and visit him? Remember it took 10 years to find him this time...if they wanted to keep his body in a secret location then it could be very difficult and costly do try and fix later is indeed it did become a matyr
  24. You can think of water in that way yes...and for water that is a reasonable way of thinking of it...only look at the oxygen. However, only considering the reactivity of molecules with respect to the heteroatoms doesn't always work. For example, if you alkylate a terminal alkyne by deprotonating it and then reacting it with a alkyl bromide, there are no heteroatoms involved (ignoring the bromide). Although, on the other side of the coin...alot of intertactions between molecules DOES depend on the heteroatoms present (e.g. hydrogen bonds). I think what you have there is just a slightly different angle on the "norm"
  25. Well...you normally take a known amount of your unknown concentration material and then add a known amount of "spike". Then you measure with whatever technique you are using, and then work backwards. For example, when I want to know the concetration/level of impurity of a sample I've made, I take a known amount of the mixture, add a known amount of dioxane and then get a 1H NMR. I can then compare the intergrals of the dioxane peak to that of my sample. Since I now how much dioxane i added and how much of the mixture I added, I can work out what level if impurity I have. Another method, if you are doing LC-MS or HPLC, is to run your unknow sample to get a baseline chromatogram. And then add some authentic standard of those compounds and see whch peak gets bigger.
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