hypervalent_iodine

Your major problem is going to be performing a Wittig reaction on a carboxyllic acid, since esters and carboxyllic acids won't react the way you want them too. Also, if you have a protected amine group, the steric bulk may also be an issue. What are you trying to make?

I shouldn't make posts at 2am. The photoisomerism reaction is actually a pericyclic, photoinduced [2+2] addition rather than a radial reaction, although a radical pathway would also result in your product. You mightn't be too aware of many pericyclic reactions out side of the Diels Alder reaction, though, so I wouldn't worry too much about that pathway.

I am indeed. Upon reflection though, I realise that this route might not work since it relies on being able to install different functionality at each end of the molecule, which I realise now would be difficult. My idea to close the ring was to install a ketone moiety on what would be the first ring carbon and a bromine on the second last carbon of that chain, make a Grignard reagent at that centre and cyclise by reacting the intramolecular Grignard reagent with the ketone: Another way you could set up your ring closure, using reactions known to you, is to brominate in a Markovnikov fashion on each of the double bonds, then eliminate them both under kinetic control to give you the terminal double bonds. From there you could cleave them with ozonolysis as you have in your method to give you the dione. I also had a quick check on SciFinder to see if I was missing any methods in preparing your ring. The one reaction that predominated is a photoisomerism reaction and involves a radical pathway. I'm not sure how much you know of those types of reactions, but I thought I might mention them. I think what might be best for you is if you realise that cyclisation reactions are typically just an intermolecular reaction applied to an intramolecular system; the reaction itself is the same, it's just that you're now using it on functional groups in the same molecule (for example, the Dieckmann cyclisation, which is an intramolecular Claisen condensation). So from here it is really just a problem of looking at your 1,2-dimethylcyclobut-1-ene, which you indicated as you preferred precursor to the final product, and figuring out ways you know to make double bonds. It might help you to make a list of the ones you mentioned in your OP and go from there. Oh, of course. The compound you listed is something I could envisage being made in a two-step procedure, so it's definitely an exercise in getting you to apply yourself to a difficult and purely theoretical situation. Well, you wouldn't be able to distinguish between the (R, S) and (S, R) enantiomers and definitely you would only get that particular configuration, since the (S, S) and (R, R) diastereomers would not be able to be formed given how constricted they would be. With that in mind then, I would say no, you don't need to consider any asymmetric syntheses, although it I am not the one marking you.

Hi KCM92, Apologies it's taken so long to get a reply. I've been (and still am) on a trip away and it seems that your assignment hasn't piqued the interest of our other members. Firstly, your initial strategy of 'working backwards' is a very good way to start things like this. Though you probably haven't covered this yet, the approach you took actually has a name, that being retrosynthesis, and is used frequently to work out synthetic routes to complicated structures. You are right to assume that the peroxyacid is more efficient than your second route. It's not so much because the reaction itself is better, but because the synthesis of the 1,2-dimethylcyclobutene ring versus the 1,2-dimethyl-2-bromo-1-hydroxycyclobutane is much easier. I'm not sure I agree with your step 2. Making the ring installed with a bromo-substituent would be quite hard. If you imagine a disconnection at the bond between the two methylated ring protons, you will note that one of the carbons would need to act as a nucleophile and the other as an electrophile. Doing this to end up with the starting material listed in Scheme two would not be able to occur in one step. Since this is an assignment, I don't think it would be fair to simply tell you what would be better. Can think of what other substituents you might be able to include in place of the bromine, which can then be eliminated to give a double bond? Once you've worked that out, you'll need to work out where to make a bond disconnection to make the ring. Feel free to come back with ideas on that and I can help you more. There is one name reaction in particular that you mentioned in your OP that would apply here. Also, I'm curious to know if you've copied the assignment down correctly? It seems odd that they would add two completely superfluous carbons.

Take the moral high ground and guilt trip him with one of these: http://www.youtube.com/watch?v=8Dx6FqFSeek

Since this thread is about ridicule and when/where it serves as a useful tool, I'm going to use this opportunity to provide an in-context example. This is getting beyond ridiculous. I have read this thread and kept up with it since it's inception and have seen the fall-back of certain member's actions within the board. This thread, while certainly not new (there are multiple others on the same topic) has shed some very interesting and enlightening conversation from both sides of the fence. Continuing to speak to brick walls, as it were, is detracting quite heavily from the work that members have put into replying to it. Asides from the obvious derailment from the OP, I don't think it is fair to those who participated in this debate in good faith to have it continue as it is. It is painfully obvious to me and to others that iNow has no intention of changing the way he choses to interact with members here. If staff members are in disagreement with this and in consideration of his track-record, then do something about it. In my own opinion, this is not the way to handle it.

Looks like someone spoke a little too prematurely there, eh? As in life, so in forum posting (or something like that).

I think a lot of that comes down to a simple misinterpretation of the presentation vs. the underpinning intentions of the language used by many scientists. Scientists are trained to communicate in a quite formal manner in order to eloquently and concisely convey their ideas to their peers. In my own experience, I have noticed that the propensity for someone who is scientifically trained to converse in this manner can be quite detrimental to their interactions with the 'average Joe'. Often, the black-and-white nature of scientific speech can be misconstrued as condescending and as an attempt to belittle a person's intelligence, which ultimately results in the actual point of whatever was being said to be largely misplaced. This is obviously not always the case - some people truly are just out to inflate their own ego at the expense of others - but it's an observation worth noting, nonetheless. I implore those who do not think ridicule is an acceptable tool in science to read or at least skim Galileo's, 'Dialogue Concerning the Two Chief World Systems', specifically the translation containing a forward written by Einstein. In this forward, Einstein notes the following: This from a time where Galileo had been expressly forbidden to advocate Copernican theory for fear of, well, exactly what he got (the Inquisition did not appear to enjoy his humorous jabs). In a rather recalcitrant and daring move, Galileo chose to ignore the warnings set before him and instead used his 'unusual literacy gift' as a means to subtly ridicule and confront the stagnant opinions (note, not the people) of the time in order to relay his ideas to the educated masses. While incorrect by our current standards, his work is considered a paramount feature in the development of our present scientific understanding and could not possibly have been considered as such were it not for Galileo's appropriate use of tactic. Arguably this example is somewhat exaggerated considering the position of modern science, wherein the powers of an individual is treated with much more skepticism and are instead replaced by the powers of the collective. That being said, I think the premise can be extrapolated to serve as quite a fine illustration of exactly how and when ridicule is a useful and indeed, a necessary tool to convey an idea, if only as a last resort.

Hypervalent_iodine couldn't agree more.

Reading a thread on another forum the other day, I found a comment that sums up an opinion often taken to extremes by our crackpot friends:

What you have to remember is that each carbon centre has 3 available p orbitals; one each on the x, y and z axis. You should recall that an alkyne bond utilises two of these p orbitals, let's say the px and pz orbital, to form two pi bonds to the corresponding px and pz orbital of the adjacent carbon, and one sigma bond along the y-axis, giving us a structure that looks like this: (Image from here) The pi bonding in allene is more or less the same concept and looks like this: (Image from here) You can see from this that the central carbon does still have two pi bonds, each using a different p-orbital, just the same as it would were it triply bonded to a single carbon in an alkyne. Interestingly (and somewhat irrelevant), the structure that allene is forced to adopt, which is non-planar (the hydrogens on one end are in the plane, where the two on the opposite end stick out of the plane), means that allenes can actually be chiral, despite not having a stereogenic centre. If you imagine that you had four different substituents attached to the terminal ends of the molecule, you can perhaps see that the mirror image of the new compound will be non-superimposable on itself, which is the definition of a chiral molecule. In fact, it doesn't even require all four substituents to be different; so long as the two substituents on either end differ from one another, it is chiral. Hope that clears things up.

Is this for undergraduate or postgraduate? As with everywhere, it depends on where you go and what area you chose to take up. In terms of the quality of education, well honestly I don't know if my opinion is very well-informed on this issue, as I've only ever studied at the one university (the same one I still attend for my postgrad work). I think, from my renewed perspective as a tutor, the tertiary education system here does its job reasonably well. If you go to the right university and put in the right amount of motivation for the right reasons, you should come out of it very satisfied. There are a few short-comings, but these are easily overcome with the right amount of investment and don't necessarily apply to every university. If you are looking at studying chemistry in Australia, you really can't go past some of the Melbourne based universities - specifically the University of Melbourne or Monash. Otherwise, UNSW or the place I attend, UQ, are both great alternatives. Speaking from my perspective as a UQ student, I can say that the course content here is definitely adequate and the lecturers, very approachable. This is particularly handy if you ever want to get some hands-on experience in a lab. I can't speak for other Australian universities, but the lecturers that I've had here have always been very welcoming to the idea of letting undergrads in their labs, which is great in terms of the learning experience and contacts you get out of it.

You don't need medicinal chemistry courses to be able to work in drug design and development. The majority of work that is performed under that banner is organic chemistry coupled with various in vitro assays to determine bioavailability, P450 metabolism, etc. There are some aspects of drug design and development that aren't covered in your typical organic chemistry courses that you will either learn in time or that would be beneficial for you to pick up at some point in your degree/before you start your career. For instance, it would be useful to know what sort of chemical modifications one might choose to make to increase epithelial partitioning or decrease enzymatic degradation of an orally administered drug. These are, however, things easily picked up for someone with a background in organic chemistry simply by looking at the literature or reading any number of medicinal chemistry texts. I doubt you'd be discriminated against for not knowing everything pertaining to the finer points of drug design at the start of a new job. Typically when you're starting out on a given project, your supervisor will provide you with a starting point and some direction of exactly what it is you'll be doing in the lab. In addition, the first week or so of a new project is mostly reading up on the literature, so you tend to learn the specific theories and concepts as you go. In short, I would stick with the chemistry department and maybe pick up one or two pharmaceutical chemistry courses along the way. If you have a solid basis in organic chemistry and a little molecular cell biology, doing a only one or two senior level courses in medicinal chemistry, or even no med. chem. courses at all, should be no problem in terms of your career.

Seeing mississippichem's error, hypervalent_iodine kindly took the liberty of removing the superfluous word from his post.

I've been meaning to reply to this. I think, to a point, we are arguing the same thing. That being said, I don't necessarily agree with what you've said here. Though certainly, the 'work smarter, not harder' adage has some major role in the way our interactions mature, I think you are perhaps overlooking the propensity for people to act recklessly for the purposes of showing off, whether that be implicitly or explicitly. I derived my initial argument based on that context. I think it may have more to do with your last point than simply working smarter. Even to a 20 year old, it would seem obvious that taking the trolly up to the bag rather than taking the bag to the trolly would be the optimal way to do things. Agreed. As an aside, I realise my last post could be taken as putting words into your virtual mouth. Apologies for that.

Moved to homework help so that the question gets appropriate attention. It might be useful for you to consider where endothelial cells and pneumocyte tissue is found and how this relates to gas exchange between alveoli and pulmonary capillaries.

Bolded, italicised, colourised and underlined for emphasis. But not before they have time to hit, 'reply', eh?

Radioactive unobtanium or similar, I should think. Maybe something from Tony Stark's particle accelerator - who can really say?! The answer to that last part is that no one can really say. People with comic book-esque super powers don't exist; trying to conjecture what they could be made of if they did exist is about as useful and scientifically valid as trying to figure out the top speed of a unicorn.

Psycho, I've already had to split this topic once. Please try to stay on topic and don't derail this thread by responding to mod notes. In any case, you're misinterpreting what mooeypoo was saying. Correcting someone's post is all well and good and backing yourself up with sources is even better, just try to keep the condescending tone in which you sometimes do it to a minimum. I want to go back to the OP for a moment, since this thread has started to turn into a book review club. Even though it doesn't appear that the OP'er intends on rejoining the discussion, I think it would be nice if we could all go back to what randomus was originally asking - i.e. are there any marine environments that we know of incapable of harbouring life. As a non-biologist, the answer to me seems to be a tentative yes, there are places, but they are very extreme. We've discussed hyperthermal environments to death and the conclusion there seems to be that, yes, things live there, though not necessarily in the most extreme cases such as deep sea hydrothermal vents. Another extreme environment worth mentioning is that of the Dead sea - i.e. hypersaline waters. If I'm not mistaken, there's not terribly much in the way of life there, although you do find some variety of microbe. I'm not up on the details there, though, so perhaps Psycho or someone might like to chime in with opinions and/or corrections.

I'm moving this to homework. Firstly, can you please fix your post, there appears to be an issue with you picture. Secondly, you need to tell us where you're at with the question - how far have you gotten and what exactly are you having trouble with?

Not necessarily. Brine simply refers to a saturated solution of some kind of salt; typically that salt is NaCl (the stuff in table salt). You can make brine just by mixing crystalline salt into a quantity of water. The water itself isn't heavier. You now have a solution containing a mixture of compounds. The density (i.e. mass per unit volume) will obviously change when you start doing this. Whether 7 to 10 lbs is 'too heavy' is impossible to say, since you've not told us how much volume you're referring to. If that were, say, 10 lbs for 1 mL of water, then yes, I would question the information you're being told. The chemical structure of water doesn't change at all; it's still H2O. What changes is that the water now forms hydration cages around the solvated ions. Oxygen and hydrogen have differing electronegativities, with oxygen being more electronegative than hydrogen. Loosely, what this means is that oxygen is able to pull electron density towards it better. When we have a look at the structure of water (image from here): What we have is a sort of electron tug-of-war. Because O is more electronegative than H, it is able to pull electron density away from the H's. Because electrons are negatively charged and because the oxygen now has a higher amount of electron density around it means that the oxygen atom has a partial negative charge. Similarly, the hydrogen, which has had electrons pulled away from it somewhat, now has a partial positive charge. We say that such bonds are polarised, because the electron density and thus the charge is bias towards one or another side of the bond. When you dissolve salts like NaCl into water, the salt will separate into ions (charged molecules); for NaCl, we have Na+ and Cl-. The water, which we've said has a partial negative charge around the oxygen centre and partial positive charge around the hydrogens, will then arrange around these ions to try and balance out the charges. In our example, the partially negatively charged oxygen of the water molecule will arrange around the positively charged sodium atom and the slightly positively charged hydrogens will arrange around the negatively charged chlorine. The structures that they form are called hydration cages or solvation shells, among others (there are a few names I've heard of) and they are the reason why salt dissolves. They look a little something like this: (from here) (from here) As you can see, the water itself hasn't changed structure at all. Now, I'm assuming here that you are wanting to dissolve some sort of magnesium salt, rather than simply wanting to throw magnesium metal in water. This being the case, the concept would be very similar if you were trying to make a salt solution with some sort of magnesium salt. The only thing that's changing is the identity of the ions you're solvating.

Nickel tetracarbonyl is a liquid, albeit a volatile one (boiling point is around 43oC). I really would not recommend making it as it for the purposes that elementcollector needs it for, as it is incredibly toxic at low concentrations.

Split the threads so this one can stay more on topic and in line with OP. New topic being here: http://www.scienceforums.net/topic/61227-hyperthermophiles/page__view__getnewpost

I suspect before you edited your previous post, the Archaea bit wasn't bolded and I missed it, hence why I changed my post Also, I should point out that I changed my post because I altered how I perceived your opinion. The links were really just out of interest's sake, not because I'm trying to point out that you're wrong.

Archaic wordage or not, it doesn't take away from the fact that they were able to culture an organism, found in a hydrothermal vent at temperatures exceeding 250oC. I'd also like to add a few more papers into the mix, which I found from the citation list of the one that Captain Panic linked: Pyrococcus furiosus sp. nov. represents a novel genus of marine heterotrophic archaebacteria growing optimally at 100°C Energetics of overall metabolic reactions of thermophilic and hyperthermophilic Archaea and Bacteria (Edited in line with Psycho's editing )