Abstract: The distinction between interdisciplinarity, multidisciplinarity, and transdisciplinarity is emphasized.
Alexandru T. Journal Name: Current Organic Chemistry. Volume 19 , Issue 4 , Journal Home. Graphical Abstract: Abstract: The distinction between interdisciplinarity, multidisciplinarity, and transdisciplinarity is emphasized. Close Print this page. But what happened is they got the ball started, all the people came dressed up fancy, and they began to cough and choke because the room was filled with some noxious gas.
And when they discovered it came from the candles, they asked Dumas to look into it. And he identified the culprit as HCl, because it turned out that the candles were very white. The wax had been bleached with chlorine, and when they were burned HCl was given off.
So the question is, what is it that holds chlorine? How did this fat, in the candles, fix chlorine gas? We can think about mechanisms; in fact, two ways that the hydrocarbon could fix chlorine. What makes chlorine reactive? Okay, now we need a HOMO to react with it. Now, one of the more interesting hydrocarbons, in this regard, is one that had been known already, for fourty years, to react with chlorine. So we would write it with a double bond. So what makes the olefiant gas reactive? And remember the name of it?
So we can use those electrons to mix with the low LUMO; and again, one of these make-and-break situations. And chloride leaves and you get this thing, which has a positive charge. Now that thing itself is reactive. What do you make — where is a low LUMO in this one? Pardon me? Professor Michael McBride: Where the positive charge is.
Have you got that too Virginia? Professor Michael McBride: Chlorine has unshared pairs, right. So, in fact, both those things happen at once. Both those things happen at once. And you can see it by looking at molecular orbitals. So those things mix. The blue orbitals overlap and mix, shift electrons toward the other one; the chloride breaks away.
So you make that three-membered ring, with two new bonds, and the chloride, as we said, breaks away. And now it itself is reactive. Can you see what would be reactive about that cation intermediate? Angela, do you have an idea of what could be a LUMO here? Does it have a vacant orbital, an unoccupied molecular orbital? But the plus will make orbitals low in energy. The plus charge will help. But what orbital will you have? Now you got two choices. You got carbon-carbon or carbon-chlorine. Professor Michael McBride: Right, chlorine has a high nuclear charge.
Professor Michael McBride: Big on carbon, because the bonding orbital was big on chlorine. And there it is. Big on carbon, the black one; small on chlorine; and antibonding between them. What do you have for a high HOMO, to react with it?follow link
Chem Organic Reactions Mechanisms I :: UC Irvine, UCI Open
Professor Michael McBride: The chloride that you had at the beginning, that you lost in the first step. Okay, so we bring it over here. It comes up, makes a new bond; that make and break. And you get that. And that was the reaction in that resulted in ethylene being called the olefiant gas. Because this is the oil that was made, by reacting it with chlorine. How about if you have methane? So you have to have another trick. And one of the reasons for that is that the chlorine has so many unshared pairs. They overlap. Is that going to be bonding, if you mix these two orbitals?
When you mix two orbitals you get a lower one and a higher one. Will it be bonding? This one will be bonding but this one is anti-bonding. Everybody with me on this? Now, so Kate, what would you say? Is it going to be net favorable or unfavorable? Two electrons went down in energy, two electrons went up in energy.
See a Problem?
But the ones that went up, went up a little more than the down went down. So having so many unshared pairs weakens the single bond. So chlorine has a weak bond. You got to do something to help it to break. Anybody know? It absorbs visible light. Now how does it take on energy, when it absorbs visible light? Where does the energy go, in the molecule? Does anybody know? Professor Michael McBride: Electrons go from orbitals to higher orbitals.
It breaks the bond. So you can do it with light, as well as with some HOMO attacking. Okay, so the bond breaks. Okay, so now we have two chlorine atoms. And now we can do the trick with the chlorine atom, because we have this SOMO, and it can mix with the C-H bond to make a new bond; that is, one electron in the C-H bond now goes each way. One goes to complete the pair, to make HCl, and the other one is left on carbon. And the nice thing about this is you still have a radical. It must be so. If you start with something with an odd number of electrons, and react it with something with an even number of electrons, you must be left, at the end, with an odd number of electrons.
Understanding and Exploiting Structure, Function and Theory in Organic Chemistry
So CH 3 is such a radical, and it can react with something, to break another bond, and it reacts with the weakest bond, chlorine. Why is it neat, that you have a chlorine atom? That can go back and start over again. And so you can get lots of products from just one initial photon of light, that started this chain along. So these are two completely different ways. Student: …why does it break a second chlorine molecule, rather than using the other —.
Professor Michael McBride: Because they have to find one another. If you try to generate too many chlorine radicals, so the concentration gets high, then their concentration will drop again, or not get so high, because they find one another and combine.
You know what the license plate of New Hampshire says on it? I use that joke later on. Okay, s to s, we have this substitution or type or unitary theory.
- Match-Tournament for the World Chess Championship 1948.
- Pharmaceutical Organic Chemistry I - Theory!
- Organic Chemistry!
- Reservoir Sediment Management.
- Going Vegan: A Healthy Guide to Making the Switch.
- Gendered Transformations: Theory and Practices on Gender and Media (European Communication Research and Education Association)!
- Organic Chemistry: Theory, Reactivity, Mechanisms and Reactions.
And that is that they had this — remember, acetyl radical had been discovered by Liebig. So there was this great element that would survive from reaction to reaction. But here was a reaction with chlorine, of this kind that Dumas had been studying, where you start with acetic acid, acetyl OH, react it with chlorine, and you get a chloroacetyl. So the element has been changed. And, in fact, it goes even further. It can react again to give dichloroacetyl or trichloroacetyl. All the hydrogens can be substituted, as we now know by the kind of mechanism, the SOMO mechanism, we just studied; free-radical chlorination, chain reaction.
So hydrogen can be substituted by an equivalent amount of halogen, or oxygen, right? But all these things you get, when you change a radical into something else, when you transmute it, have similar properties. All of these acids — acetic acid, chloroacetic, dichloroacetic, trichloroacetic, are all acids; they all taste sharp and so on.
You get the same type of molecule, even after you have a substitution. So by , four types were recognized as prevalent. One was water, another was hydrogen, another was hydrochloric acid, and another was ammonia. So, for example, you could have these structures; and this drawing with a curly bracket like this was the notation used by the people who did Type theory. So you have water, hydrochloric acid, hydrogen and ammonia. And you could exchange, make exchanges, for the hydrogen. So, for example with ammonia, you can substitute ethyl for hydrogen and you could get ethylamine, diethylmanine, or triethylamine.
But these were all basic. They react with acids, why? Professor Michael McBride: Yeah, they all have the unshared pair on nitrogen, we would say. Or you could have ethyl alcohol, which is of the water type.
Or the potassium salt thereof, which they would say is the potassium-ethyl analog of water. Or of the HCl, you could have ethyl iodide, where you exchanged hydrogen with ethyl, and exchanged chloride with iodine. Fairly unreactive. So this particular reaction was named for the work, in , of Williamson in England. So how about the theory of these types? And Williamson, Alexander William Williamson, who we just mentioned making ether, said this is something new.
At this time Dumas was years-old.
So he was really getting over the hill. Have you seen these devices? Journal of Chemical Education Physical Organic Chemistry. Second Edition. Theory and practice in the organic laboratory, second edition. Chemistry experiment and theory, second edition Allen, Thomas. Many of these large sections contain discussions, e.
As with m y g o d dirrwnnry, the definitions dostnnd on their own. The value of this kind of book depends, in my opinion, on the quality of the definitions, the inclusion of all appropriate terms, and the ability to find these terms quickly. I think the authors succeeded on all these points. The definitions, especially with the inclusion of the illustrative examples, were a t the very least adequate and most often excellent. I thought of very few terms or concepts that I could not find in the hook, and these were debatably either obscure or of very little interest to most organic chemists.
With the aid of the chapter titles, the table of contents for each chaoter. I also had no difficulty in locating the majority of theterminology quickly. Finally, I should note that the hook contains very few typographical errors and the drawings are first-rate. Lowry and Kathleen Schueller Richardson. Since I have taught a graduate course from the first edition, I find this new version to be well done and a solid improvement. I particularly like the divisions into chapters on aliphatic nucleophilic substitutions since this makes it easier for the transition far a heginning graduate student.
Chapter 6 on Carbanions, Carhenes, and Electrophilic Aliphatic Substitution ties together important chemistry in terms of eleetran-rich reacting species. The introduction of perturbation theory and symmetry considerations in Chapter 1 should ease students into this important aspect of modern organic theory.
Previously, this material had been placed in a late chapter Chapter 10 in the first edition. This reviewer found Chapters 1 and 2 oartieularlv well done and useful for beeinning graduate studrnrs.