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Everything posted by hypervalent_iodine

  1. A FC acylation to add an aldehyde to the ring? So you want to add a formaldehyde moiety to the ring? You couldn't do that with FC anyway. Formyl chloride is way too unstable. Did you maybe mean something else? Anyway, why do you need to add the amine first? I had a think about what you needed to make. Starting from benzene I would follow with the initial nitration and hydrogenation to the amine. Amines are para activating, so you can then do another nitration to get para nitro aminobenzene. I would then convert the amine to a diazonium salt (using NaNO2 and HCl) so that you can convert it to a nitrile with Cu(CN)2 and KCN. The nitrile can then be changed to COOH with conc. H2SO4 in water. Then it's a case of hydrogenationg to get the nitro to an amine - though I'd be concerned of turning the acid into an alcohol. I just did a quick search around a science journal search engine and apparently there are ways around it. I'm not sure of the conditions though. Also, is this a theoretical exercise or is this for something else? Seems like a mundane and pointless sort of thing to need synthesising on it's own when you can buy it.
  2. I just did a little bit of research on the topic and from what I gather, they will not have the same composition as they are broken down via two very different mechanisms. When you bury a body, the bones may chemically decompose as a result of soil acidity (as mentioned) or biologically decompose via bacteria, which effectively consume the calcium stores. Burning a body is very different and doesn't actually produce ash, rather dry bone fragments, which are then pulverised to ash. The ash tends to contain, "dry calcium phosphates with some minor minerals, such as salts of sodium and potassium. Sulfur and most carbon is driven off as oxidized gases during the process, although a relatively small amount of carbon as carbonate may remain." (that was from wiki). I think that's correct.
  3. Checked out your mechanism, Horza. It seems perfectly logical to me!
  4. You should also look up the principles of osmosis. Drinking sea water will actually dehydrate you faster. If you had some basic equipment, you could set up a still and remove the salt before you drink it.
  5. I think you need to reference you sources as well. How do you explain the abundance of dinosaur skeletal remains? These are 64 million years old, sometimes more. As with imatfaal, I am not an archaeologist or some sort of decomposition expert.
  6. The stomach is the least of your problems! If this is going to be an orally available formulation, you need to try and get the drug into the blood stream via the small intestines - which in itself is a nightmarish task for a lot of compounds due to the plethora of enzymes around, just waiting to chew all manner of things up. Event then, actually trying to promote passive or carrier mediated diffusion (those aren't the only ways, but they're the major ones) without compromising the activity of the drug can be an issue. Once in the blood stream , you have to make sure it doesn't do anything funky in the liver - what with all the P450's about - and try to maximise the time in the body by reducing its propensity towards renal excretion while at the same time making sure it isn't going to be in there too long so as to be toxic. If the drug isn't specifically targeted to the cells it needs to be in, you have to make sure the drug won't be toxic to other living cells in the body (it's in the blood stream remember, it's going to go everywhere short of the brain (hopefully) - unless the brain is your target, in which case you have the issue of getting through the blood brain barrier). What chemists do to mimic these things are assays such as caco-2 cell layer tests, which is a mono layer of homogenous colorectal carcinoma cells used to test how well a drug can diffuse through cells; P450 tests, which is an in vitro test used to see how the drug will be metabolised in the liver, etc. The last one is a VERY important test. P450's are the most abundant type of enzymes in our livers - they metabolise everything. There's no point in having a drug that isn't going to work and may very well be altered into toxic when it gets into the blood, is there? Anyway, so you see my point. If this person wanted to do those sorts of tests, well they couldn't do it unless they were in a lab.
  7. Oxidising agent 5.1 is a hazardous substance reference number. Chemists use such numbers to assist in the proper storage, disposal and safe handling of chemicals. So no.
  8. What kind of technology are you referring to? Scientists rely heavily on technology to be able to investigate and justify their hypotheses. We can use it to make images or slides more resolute with microscopes, we can observe the structure of compounds using various spectroscopic tools (such as NMR machines, etc), there's the LHC and all of the machines that we use for medical diagnostics.
  9. I did a chemistry major at university and didn't touch a single maths subject until I was in my second year, where I picked up a second year linear algebra course. I of course had to study a little harder, having not done maths since high school, yet I still managed to get full marks in all my weekly assignments and did quite well in both the mid and end of semester exams. At one point I was even tutoring a friend doing the course with me - he who had done all of the pre requisite first year maths courses whereas I had not. I think the key for some people is just the motivation to do extra work when you don't quite understand enough about a concept to apply it. I spent hours going over tutorial sheets and lecture notes until I could fully visualise everything. Another thing that was pointed out to me by a friend who is doing Electrical engineering is that as our pool of knowledge expands, we have to push more and more of the concepts that we would traditionally learn at a university level to lower secondary levels to make space for all the new 'stuff' (for lack of a better term). He does a lot of tutoring for high school students in maths and was quite taken aback himself to come across a student needing help with an area in physics he himself had only just covered in a second year fields course. When you think about it too, some of the basic areas that we have learnt about in high school would have, at some point in the past, been exclusively university territory.
  10. Do you mean conversion of an amine to an alkyl halide? Looks to me like you're forming a diazonium salt with the NaNO2 and H2SO4 (though, normally you see HNO2 used). Then it's just a nucleophilic substitution. You see this a lot in text books being used on aromatic systems. If you want pictures, you should look up amines on wiki and scroll down to the reactions to form the diazonium salt and then click the diazonium link to see the nucleophilic substitution mechanism. Hope that helps.
  11. One of the reactions I did was with a glucosamine hydrochloric acid salt, which was to be the second monomer unit of a tri-beta-1,6-N-acetyl-D-glucosamine. I was in the process of synthesising a potential vaccine for a particular biofilm forming bacteria and so I needed the synthesis to be really short for it to work commercially. The people I spoke to about trying to cut down my protecting group steps said that I could protect my C-6 with a TBDPS group, in the presence of the amine and 3 hydroxyls, without any trouble. I did pretty much what you said - I added it (under nitrogen) drop wise at room temp over about 10 or so minutes for 4 mL of TBDPS-Cl and it worked beautifully. I didn't get to analyse the yields until 2 products later because I carried my products straight through, but after 3 steps I had almost 70% yield and the TBDPS didn't appear to have gone anywhere else I didn't want it to. The main difference in reactivity I think is the steric affect. You could also argue that, depending on reaction conditions, the stability of their respective deprotonated forms may also have an affect on reactivity - i.e. a secondary or tertiary centre would get a heavier pull of electrons from all the extra alkyl groups than would a primary hydroxy, thus making the primary anion more stable. In my experience, I have found that you can often use the difference in reactivity to your advantage, if you do it carefully enough. And yes, there are so very few synthetic chemistry posts on here, which is unfortunate. In any case, it's always nice to talk to an organic chemist who understands the jargon!
  12. that won't be too hard. Protecting groups coupled with the added reactivity of the primary spot will make it a fairly simple process. You know, the funny thing is that ekay is probably not even going to read this. I have enjoyed the exercise though.
  13. Or you could just start with ribose/arabinose, etc, eliminate the primary hydroxyl, then methylate. EDIT: probably better methylate and then eliminate actually, which would mean an extra protection/deprotection step for the primary OH.
  14. That's not really true, Horza. I have often protected sugars in the C6 position with all the other groups unexposed. It works fine if you do it properly - or it did for what I was working with. Tosyl may be a problem, but it then again, it may not. And you don't really seem to have taken into account that there is one less carbon in the product? Oxidising all those hydoxys to ketones would be slow and painful and probably not work. Also, what do you intend to oxidise with - remembering that the aldehyde functionality can also oxidise quite easily to the acid. Whether or not you can make two acetonides depends on stereochemistry as well. You'd be better off going with Bn or Bz groups. It does depend on how you remove the OH in the end product due to different sensitivities of the various PG's. Oh, and though it is slow, you may also end up reducing the methyl esters, especially since you would have to use so much to reduce all those ketones you somehow plan on making.
  15. Can I ask what you intend to use it for?
  16. As an organic and medicinal chemist myself, I completely and 100% agree with insane_alien and everyone else here who has tried to tell you to give up on this idea. DO NOT DO THIS! Even if you could manage to acquire the chemicals and set up some sort of backyard apparatus, you have, as was mentioned, no way of determining purity and even whether you got the correct product. This is a extremely idiotic idea to even contemplate. Pharma companies and scientists involved in R&D do not simply make a product and feed it to people/animals (or even any of the other artificial testing set ups) with out first purifying and checking that it is EXACTLY what it should be. You cannot possibly do that without a lab and millions of dollars worth of equipment. I hope that in the few months since the last post here that you haven't pursued this any further. You are putting people's lives at risk if you do.
  17. alpha-d-glucopyranosyl-(1->2)-beta-d-fructofuranoside Also known as sucrose.
  18. My boyfriend works in polymer chemistry at the moment (I myself am an organic chemist, so not much help). A great place to start looking for what people are doing is on the Science scientific journal website (you can get it on science.com). There's a lot of work currently going into finding biodegradable polymer plastics for use in things like plastic bags, take away cups etc. There's also a lot being done using polymers to formulate some drug delivery systems. Unfortunately, a lot of stuff that polymer chemists do involves working on a nano scale, which involves lots of expensive equipment you wouldn't get in high school. I think the synthesis of nylon is something you can do at a high school level, but that's maybe the extent of it.
  19. I certainly do I haven't looked much in to adding a Tosyl group to C6, but I am almost sure that if you did it very slowly and very carefully that you could selectively add to the C6 without disrupting any of the other exposed hydroxyls. And yes, you would start with a Tosyl chloride. The other problem you have with this is that you cannot simply 'eliminate' the hydroxy this way. Doing so would require temperatures in excess of 200 degrees C and you would end up with an alkene, which then needs further reduction. I would try use something like the Barton-McCombie deoxygenation. Traditionally it doesn't use a Tosyl group on the OH, but instead converts it to a thiocarbonyl. I think using tosyl should be fine though. The next step uses AIBN and Bu3SnH, which I would be concerned about using with around all the other OH groups exposed, so I would go about protecting them after you've added the tosyl. Probably as benzyl ethers, since you'll have to remove them before you shorten the chain. You can use Bn-Cl for the protecting group reactions, but be careful to check with NMR etc that you have fully protected every hydroxyl group. A lot of the time when you're simultaneously protecting a bunch of different hydroxyls, they tend not to all go on and you have to repeat the reaction. Again, I would really not use glucose for this. Asides from all the horribly long and painful synthetic steps, you will end up with two different products. Are you able to use ribose or arabinose at all?
  20. I agree with Horza, to an extent. Having worked with sugars extensively in the past, I can promise you that the reaction you're doing is best not done with glucose. Asides from the fact that sugars are a pain to work with - you can't heat reactions above 35 degrees celsius, protection and deprotection steps are a pain (low yields, shifting protecting groups etc) and commercially, not viable (if you have to do a lot of them) - your end product is a 5 membered sugar. Why are you starting with glucose, when arabinose and ribose are readily available? Regardless, your ring opening reaction (using glucose) will be difficult and you cannot simply 'protect the C6 hydroxyl once it's open", as glucose will spontaneously ring close when in solution. Your product has one less carbon in the main ring (I'm not including the ether linked methyl groups in that count), so instead of protecting it, you need to change it completely and shorten the chain. You can do this by treatment with NH2OH to generate an oxime, then generate the cyanohydrin with acetic anhydride and sodium acetate. From there it's simply a case of treating it with sodium methoxide in methanol to expel the cyanide and generate a mixture of ribose and arabinose. This will then cyclise to give the corresponding furanose. You can work from there pretty easily. Also, protonating the oxygen to remove as water isn't the most efficient way to go. You're best of activating it with Tosyl or something like that. As I say, long winded and painful. As well as that, reactions with cyanide leaving groups in them are not ideal due to toxicity issues. You'd be much better off actually starting with arabinose or ribose than you are glucose.
  21. Hi! I'm Kylie and I am an organic chemist, currently working on radical substitutions on aromatic systems using hypervalent iodine reagents. I love all things organic chemistry and I am partial to some areas of biology and maths. I have a passion for teaching and assisting others in their understanding of chemistry - the more chemists in the world, the better!
  22. I'm not sure if this has been said already, but since non-ionic carbon has a full set of bonds and no lone pairs of electrons, it is incapable of exceeding its valency by virtue of the orbitals it has available to it. Many atoms are able to exceed their valency on account of having empty, low-lying (in terms of energy) orbitals, such as d orbitals. You mention CH5+ in the last post. The ONLY place this is ever, ever shown in text books is in chapters dealing with mass spec. Even then, there is no proof to say it is actually a species that exists. Pentavalent carbon is not something that can exist, especially CH5+.
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