 Welcome to this lecture on transition metal organometallics in catalysis and biology, and in this series of lectures we have looked into various reactions that are important to catalysis, particularly from the industrial perspective in terms of industrial scale synthesis, and we have been looking at the applications of organometallic chemistry in a big level. In this series of lectures in the last few lectures we have looked into olefin metathesis, particularly alkene metathesis reactions, we have looked at how it was developed, the story behind their development, discovery, development mechanisms and also the various types of metathesis reaction that have been subsequently discovered and are put under same umbrella as the class of metathesis reaction. Continuing further along this discussion, we are going to be discussing another important topic, variant of metathesis reaction, particularly the cross metathesis reaction. The cross metathesis reaction is given by the following equation, and it is represented by, so this is sort of intermolecular metathesis reactions, intermolecular version of metathesis reaction. Now these cross metathesis reactions, the applications of cross metathesis reaction is significant, and the development of cross metathesis reaction for industrial purpose application is also very interesting. Now, let me just give a brief overview of the story about how this cross metathesis reaction came into being, particularly for utility in industrial scale applications. Now these all began back in 1960s or 70s, particularly when people were trying to make these large scale synthesis of olefins. Now, the story starts with the need for developing soft detergents, need for developing soft detergents, which are nothing but linear chain, linear fatty alcohols, as opposed to hard detergents, which are branched fatty alcohols. Now, these branched fatty alcohols, they were sort of being sold by shell, by shell development chemicals, and these hard detergents are branched fatty alcohols, long chain alcohol branched long chains with alcoholic ends, these are called long fatty alcohols, they were causing a lot of depositions of foams and on the rivers, the foams and surfactants on the rivers, and it was sort of creating a biological ecological havoc, and there was a need, and because of lack of any method for their degradation, there was a need to develop the soft detergents having linear fatty alcohols, so that is how the story starts, and fatty alcohols that time were in high demands and had a lot of market potential, so they were in high demands, with a lot of market potential. So, the idea was to access these long chain fatty alcohols, and they primarily were being produced from hydro formulation, from alkene, alkene in presence of chlorine to give long chain alkene to give alkyl halide, that would undergo HCl elimination to give olefins, and that olefins under hydro formulation, and then subsequently a reduction would give these fatty alcohols, both linear and the branch, so that was the method at that point of time, which was being used for producing these soft and hard detergents, which were obtained from the fatty alcohols. Now, the other way of accessing these olefins are from cracking petroleum, large scale cracking of natural oil, natural gas, so there was sort of a demand to go all the way from olefins to these detergents via this alkene halide, then olefins, and then hydro formulations, and so on, so forth, this is alkene. Now, at that point the shell chemical discovered shop, Shell Higher Olefin Polymerization Process, which is called Shell Higher Olefin Process. So, what is this method? This method actually converted ethylene to alpha olefins, not alpha olefin oligomers, and not polymers, and the catalyst used for this is nickel. Nickel was found to produce alpha olefin polymers from ethylene, but the other process also went on to become a very big industrial hit, and even won a noble prize, and this is Ziegler Nata polymerization, if same olefin, if it is taken with titanium and aluminum halides, then it can make polyolefin polymers. So, Ziegler Nata will take olefin all the way to polymer, whereas the need was to develop alpha olefin oligomers, so they are not too high of a molecular weight, and that was developed by this Shell Higher olefin process by Shell Chemicals. So, this is the industrial process, which could stop the polymerization of olefin all the way to polymer, and could isolate them in oligomers. So, this was indeed a big discovery, and then what is important was that these oligomers that were being produced by Shell Higher olefin had several fragments, like it was a mixture of oligomers, and then they were at a stake in trying to find out how to utilize all of the fractions of these oligomers. So, it best illustrated the point when they were looking at the concentration of alpha olefin produced. So, this is the mole percent of alpha olefin produced versus carbon number. The distribution was like this. This is called Schulz flow redistribution of alpha olefins produced from a shop process. So, what they observed that there is a large amount of alpha olefins produced, which are lower than C12 fragment, this is C12 fragment, and there is also a large less, much less number of olefin produced, which was above C18 fragment. Now, this was the distribution. Now, what was important over here is that from this distribution, only this bottom part from C12 to C14 was of importance for detergent range, for with them they could make and tap this detergent. So, the middle portion, so there was no control for swap process, and it could give a lot of alpha olefins, less than C12 atoms, and then there would be a substantial also, which are more than C18 atoms, which had no use for detergent purpose. The overall focus then was in how to use these two fractions, how to use these two fractions, and this whole story was developed in Shell, and what the idea was that this is where they took the help of other chemistry. So, the strategy was first these alpha olefins of less than C12 fragments, and greater than C18 fragments to be isomerized, that means that for example, if there is an alpha olefin, it would have somewhere in the middle the olefinic bond getting isomerized with the total number of n being remaining the same. So, some sort of isomerization of the olefinic bond from alpha position to some internal position, that is what they looked at, and then the next strategy was metathesis, then to perform metathesis of these isomerized less than C12, and greater than C18 fractions. Now, the idea is that if these two fractions are done metathesis of, then they would give products, which would be in this range, and again that can be used for detergent purpose. So, this was really a very clever way of utilizing the olefins, which are supposedly non-usable at that point of time, and hence the idea was that for them to do isomerization followed by metathesis, which will give fragments again in this range of C12-18, and then they can further use it for the purpose for which the plant was built. And this is best illustrated in the following slide for one octane, and this is C8 fragment undergoing isomerization to give four octane, and similarly CH217, this is called one ekeocene, this is C20 fragments undergoing similar isomerization to give C8, this is called 10 ekeocene fragment, which after isomerization would be subjected to metathesis to give C10, C14 fragment, which is called 2 tetradesine, so and this is the C14 fragment. So, what is interesting to note is that in industrial scale by taking the less than C12 and greater than C18 fragments, for example, one octane with C8 and one ekeocene with C20, then undergoing isomerization giving this C8 and C20, which would undergo metathesis to give the C14 fragments, and this is in the middle for use for making the detergent reagent. So, this is a very nice way of utilizing the alpha olefins, which were unusable at that point of time. Now, what is important over here to notice that fact that both of these olefins are synthesized from ethylene using shop cell higher olefin process. So, now if somebody, what shell wanted to do is to apply three chemical reactions in industrial scale, and the three chemical reactions all in a same plant, and three chemical reactions would thus be this is number one, then isomerization number two, and metathesis number three. All of these should occur without interfering with any of these, and then give the right product. And we have seen that the used for each of these are different. For example, for the first step it is nickel, whereas for the metathesis step it was ruthenium. So, there is a lot of optimization that they had to undertake in order to bring compatibility of three large scale processes, three different chemical reaction, and then in an industrial scale to be able to produce the fragment they need. Now, in today's lecture, what is important is that this metathesis reaction, what they would be carrying out over here is nothing but cross metathesis. This metathesis reaction is actually a cross metathesis between two different olefins, that is exactly what we are seeing it. So, this shop process containing cross metathesis is a large scale industrial applications of shop as well as of metathesis chemistry. Now, towards this and a lot of research has to take in place, there were people expert in shop chemistry, developing shop chemistry, then people expert in isomerization chemistry as well as people expert in metathesis chemistry, wherein put in place to come up with a single flow diagram in which this whole sequences that has drawn out here could be realized in an industrial scale, and that led to the following flow diagram for the shop production plant, which is shown over here, that is given by first the ethylene feed. So, that would enter the oligomerization chamber, then that would lead to a second chamber, which would be used for catalyst recycling. So, the nickel catalyst used for shop would be recycled back for next phase, then comes the distillation chamber, which will give alpha olefins for market, and these would be C12 to C20 fractions, C18, C12 to C18 fractions, they would be straight away used for market, and then the remaining fractions, which are less than C12 and greater than C18 would be taken to the fourth chamber, which will involve isomerization, and then post isomerization, the next what remains is cross metathesis, cross metathesis, and these would of less than C12 and greater than C18 fractions, and then finally the product would be C11 to C14 fractions for hydroformylation and benzene alkylation, so the next formats would be used for that, and the remaining, the smaller one would again be recycled, which is less than C10 and greater than C14 olefins. So, this is a nice demonstration how the need for detergent grade alpha olefins lead to development of three important major industrial reactions of all being carried out in a plant, and this was developed by cell chemical, and a nice article about this prospective development has been given by Wilhelm Kein, who had been witness to this development of shop from the industrial research to that of the industry, when he was working at a cell chemical, and has given a nice account in Angiocam International Edition 201352 12492 212496, so with this I come to the conclusion of today's lecture, which was on cross metathesis, particularly with regard to the applications of cross metathesis, and in this perspective we have taken up the whole developmental story of a cross metathesis reaction with respect to the cell hydrolefin process, which was developed at cell chemicals, and the whole perspective given from Professor William Kein in the perspective given in Angiocam International Edition 2013 volume 52 12492 12496, this is an excellent read, I suggest all the students of this class to refer to this article, and to see how the need has led to interesting development, and here it was one which was done at industry, where three big reactions were put in place for large scale production to arrive at the need of what they wanted, which was about mid range alpha olefins, so with this I conclude today's lecture, and I look forward to discussing more on various application aspects of cross metathesis reaction when I meet next, till then thank you and goodbye.