hypervalent_iodine

I'm having a little trouble accessing the proxy server for my university, so I'm unable to get the paper at the moment. A few things at a glance. It would be called 2-amino-4-nitrophenol, not 4-nitro-2-aminophenol. By alcohol, I assume ethanol? How are you extracting the precipitate from the acidic mixture? Are you monitoring your reaction with TLC? If so, and you should be, how does it look before you add it to the rhodanine solution? Obviously if the diazotization doesn't go to or near completion, you will get lower yields. As to whether the starting material messes with the second part to your synthesis, I'm not sure, but I doubt it. At a guess, I would say that the precipitates you're getting when you acidify the solution could be ammonium salts. It would also explain why the precipitate is soluble when you basify it. I wouldn't precipitate under basic conditions, since you will pull through a bunch of impurities and starting material. Are you asking whether or not you need to add water to participate in the reaction? If so, then no, but you will have water in the reaction whether you like it or not as it will form during the reaction and is of course in your HCl solution. Ignoring that, you would still want water as a solvent in this system as you need a solvent that is polar and can solubilise all of the charged complexes that are present in the reaction. Water is very good at that. I would be careful with adding conc. HCl (in fact, I wouldn't do it at all) and the concentration of NaNO2 should be kept as it is. If you are meaning that you want to add molar excess of the nitrite, I would also avoid that until you've played around with the reaction time. You need to be checking the progress of the reaction with TLC. Chances are, you aren't going to get it to work in the exact time frame stated in the paper. Edit: Another thought regarding the addition of base. Generally not a good idea given that it might hydrolyse your rhodinane component.

I don't mean this to be rude, but I have to ask if you have much experience in synthetic organic chemistry and furthermore, if you have experience in handling sensitive compounds? Diazo aromatics are typically shock sensitive and will cause an explosion if you don't handle them correctly. Nitro aromatics will do the same. I'm happy to answer your questions here and will do in due course (I need to have a look at the paper), however I would like to er on the side of caution first and make sure you are fully aware and fully prepared for this kind of synthesis. Also, you don't usually use beakers as reaction vessels, you would use round bottomed flasks. I haven't looked at the paper, but I am skeptical of the fact that it would specify the use of beakers.

Yes, but they're not perfect. There are a number of groups that use computational models to design certain compounds for use as high energy materials, drugs, etc. It's used extensively in protein docking studies as it helps in designing substrates that will bind to the active site of various proteins. There is also combinatorial chemistry, of which there are mixed opinions depending on who you ask. A major and related problem as I see it is that current research is being forced to focus on a very small subsection of chemical space. A large majority of new compounds are designed with the purpose of drug applications in mind and these are required fit into a very restricted window of parameters pertaining to things such as molecular weight, lipophilicity, etc. Funnily enough, a large number of drugs that were designed, marketed and successful prior to this being implemented are so far outside of these limits that if you were to suggest their use today as a new compound, you would probably be laughed at. The problem with this is that it narrows the focus of chemical space to the point of ignorance and this can be particularly detrimental to the application side of things. Eventually, research will have to start venturing outside of this as screening methods become more thorough and more efficient. In fact, even now I have seen a few papers where this issue has been realised. It will likely take a little more time before anything is properly done about it, however. Entire periodic table is a biiiiiig stretch there. In fact, it's plain wrong. It contains most of the useful elements to an organic chemist, but by no means does it contain all elements, ever. As for the potential for developing reactions based off of what occurs in plants. Certainly, exploring the mechanistic aspects of these reactions is useful in the sense that it opens the way for developing new reactions ex vivo. Actually utilising these reactions can be problematic. While bio-mimetic synthesis is a great idea in theory, in practice it is often superseded by more convenient and preexisting synthetic approaches. Quite often they simply don't work at all because trying to recreate the reaction conditions can be quite difficult to do. You could potentially exploit the plant or at least the enzymes to do the reactions for you, and the latter is certainly an active area of research, however they both come at a cost since enzymes are expensive and separating compounds from plant material is both time consuming and wasteful. No new compounds? Quite the opposite! There is a large area of research focused on structural elucidation of secondary metabolites from plants, etc. It's been going on for some time too, so there is also a lot of research out there. Some of my favourites are the hetisine type alklaoids. They have this wonderful heptacyclic fused ring system that is an absolute nightmare to draw and even worse to make. They've been known since the 50's and since then, over 100 have been discovered. You'd think we'd have making them down to a tee, but in fact there has only ever been one made successfully and it happens to be the least structurally demanding of the lot. No points for guessing that these are part of the focus of my research. Another very interesting avenue is marine sponges. There is a group a level down from where I work that uses these to extract all sorts of whacky compounds from.

Do you not think that maybe this would have been something better addressed by contacting staff directly? Really, if you actually wanted to know finer points of the rules here, it seems much more obvious to simply talk to those that enforce it. Members here can certainly conjecture and offer opinions on the rules, but if you're asking where the line actually sits, those opinions are serving no purpose whatsoever.

Realistically if the solvent boils at 100 degrees C, a rot evap would get rid of most of it and a high vacuum pump would do away with the rest. Well, the idea would be to extract it into a more volatile solvent such as ether, which would make drying the compound considerably easier. Also, you might not need as much extraction solvent much if you wash it with saturated brine. This is, however, based on possibly faulty assumptions as to the nature of the compound. Also, just noticed this: You would heat it slowly until you distilling solvent across and leave it until it stops evolving. If temperature is a problem, used reduced pressure. This has been said before in this thread but I don't think we've gotten an answer as to whether or not it's been tried. If the compound melts, it's really not an issue. It won't boil across unless you massively overheat it and it will solidify again once you cool it down.

The other way is to try and do a liquid-liquid extraction. If the compound is organic and the solvent isn't (I'm assuming it's water), you should be able to pull it out into an organic solvent like ether or DCM. Worth a shot, anyway.

Can you get it characterised or is this for coursework?

Keeping it covered should definitely help and as elementcollector said, temperature will also affect it. Try just doing it in the dark and seeing what you get with GCMS and NMR. Also, 'thinking it hasn't worked' isn't a very useful analysis unless you can justify it. Have you run any NMR on it?

I wrote that on my phone, so the fact that there was only 1 mistake is actually a surprise.

The neg rep was from me and was a legitimate mistake (the touchpad on my Mac is a bit sensitive sometimes). I would have asked someone to fix it, but frankly I didn't care enough.

md, the other thing you have to realise is that a huge portion of what went on with Ushie happened through PM. I had her send legal threats, abuse, constant lies and all the while, she was crying bloody murder over situations that were completely misrepresented and misinterpreted. And this isn't the first place she's done this. Honestly, I don't think anything that happened was unfair. The fact that she lasted as long as she did was purely based on the fact that staff genuinely wanted her to become a contributing and productive member (myself included). Within a day of coming back she'd already broken the terms and conditions on 2 counts. There is a point where you have to say enough is enough. The English barrier, to me, wasn't an issue until she starting trying to (badly) correct others on their spelling and gramma. I think what rubbed people the wrong way on the boards most of all was the superiority complex. Just my 2 cents.

Though it seems a little strange to say, I don't think that's the point. She is herself saying that she is proud that peple are not agreeing with her or that they think she is wrong, etc. I'm sure somebody, somewhere agrees with something she says; you've at least proven that much. That being said, I don't think it invalidates what Captain Panic said. Which isn't to say it doesn't happen. I know I've admitted to it plenty of times myself and I frequently see posts by other res. experts that are prefaced with, 'I may be incorrect on this', or something to that nature. I agree with this to a point. I think that there are certainly some members here who use ridicule as a means of debate far to often and too readily. There are some members who I think perpetuate the arrogant scientist stereotype and this is, in my opinion, goes against what should be (and usually is) the nature of this forum. It is a real problem because it does and will continue push new and potential members away. Regardless of prior knowledge (and ignoring the case of crackpots), a person should be able to come here and engage in discussion and not walk away feeling like a complete idiot for asking a question. Most of the time that expectation is met, but there are always the few rotten apples, as you've noted, and it's those rotten apples that people tend to remember in favor of the good ones. What I don't agree with is that your post seems to be implying this issue only applies to staff, which I find to be an extremely unfair assessment. I may be wrong in this interpretation, however, so feel free to correct me.

Oh, it's great. The concept behind what you have to do is fairly easy to guess at. The hard part is actually doing it. This one is kind of the opposite to Art Heist. Doing the puzzle is easy, working out what you have to do is not. I can confirm that cutting them out is the first step, though.

The obvious question I'm surprised no one has asked yet is what solvent are you using? If it's water, then you can remove it azeotropically. It takes ages, but it means you don't have to use temperatures that are too high.

Thread moved to philosophy since this isn't really a question of any theoretical concept in physics.

I only brought it up on account of Fuzzwood's comments, which suggested that 9 was an incorrect answer. It is definitely strange that a calculator would give an answer of 1 to that question. Edit: looks like there's an explanation to it after all. I don't think I used calculators much in the 1990's on account of the fact that I was only just learning multiplication and division with 3 digit numbers

So far as I know, there is no order of preference for division and multiplication and in situations as above, you have to do the operation from left to right (making the answer 9). It's also worth noting that this question brings about a rather tired debate, for which there have already been a number of threads.

Ushie, If you are going to copy material from elsewhere, you need to include references (a simple link will suffice). Preferably, just link the article(s) you took all this from (here is the link to the major part of it) and give your opinion rather than soap boxing. It makes it considerably easier to read. Do you have a point or opinion on what you've copied that you would like to discuss?

Imatfaal: The competition is all online. From memory, team registration is in June or July and the competition is shortly after that. If you go to the page I linked in my OP, they give more details there. You can access the puzzles without registering a team and have a look at all their archived ones for an idea of the sorts of puzzles they dole out. Xitten: Not having instructions is part of the fun! Some of the harder puzzles have you sitting and staring for a good amount of time with no clue how to start. When you do a few of them, you start to develop a feel for what to look for and what you have to do. The answer itself is always pretty obvious when you eventually get to it, it's the journey that's the difficult part. For this particular puzzle, the idea is to treat everything as a kind of crossword clue. From there you should be able to notice a pattern and how to link the table and the list together. There are other ones that are much harder and require more than just word skills to solve. My two favorite puzzles from that year's competition are these: Squares and Triangles and Art Heist I would have used either of those in this thread, but to be honest it seemed a little unfair. The first one isn't one you can just do by looking at it on the screen and the second one contains an Australian culture reference that I'm not sure anyone outside of Australia would be at all familiar with. But hey, feel free to prove me wrong on that. Then of course there are the ridiculously hard ones, such as the one I posted in my previous thread.

That'll be it (and in great time, too). It took us a bit longer at the time because we were working on all of the other puzzles as well. Though that being said, the team that won the competition had it out within less than half an hour. Anyway, well done to you both. There are some cookies in the mail for you.

Thought I might share another favorite from last year's CiSRA puzzle comp. This one is a little easier than the last one I posted here a while back, so I expect some answers (imatfaal and Phi, I'm looking at you both). The puzzle is called 'Togetherness'. Colloquially, non-main characters of an MMORPG player Silver Backside in Britain Strait separating Russia and Alaska Near; beside; through the means of Hardened skin, such as found on the soles of the habitually shoeless Metal currency Unchanging A table for reading or writing on Ran away from danger A rood screen, or Australian jelly-like confection Misplace something, or come last in a competition Administer, run, or handle something Female horse Defeating someone at chess Relating to the mind Inert gas used in lighting From; belonging to Insistently encourage Small container for liquids, usually medicine There are three hints, which are as follows: Hint 1 Hint 2 Hint 3 The first two are a bit enigmatic, but the third one makes it pretty obvious what you have to do.

I'm not really familiar with piezoelectrics. Feel free to make a thread on it in the Engineering forum though and I'm sure someone else will be able to help.

Definitely amorphous. If it were crystalline, the material would be a lot more brittle and rigid, which is probably not so good for something marketed as foam. The picture you linked there looks a little odd and might be a bit confusing for you. You'll notice that there are diagonal lines that cut through the structure in between each monomer unit (i.e. between each repeat of the basic chemical unit). If you have a look at the first image, it cuts between two monomer units and each of them is slightly different - the double bond geometry has changed circled in my picture below). What this means is that the polymer consists of repeating units of either the first or second type and they occur at random intervals throughout the polymer structure. To illustrate this better, if we say the first type of unit is called A and the second one is B, the polymer might look like this: You can draw it how they have in the image if you'd like (avoid the second one, those silsesquioxane things are a pain to draw) or you could simply draw this: