 I once again welcome you all to MSB lecture series on interpretive spectroscopy. So I've been discussing about representative examples from each type of organic molecule. So let me continue from where I had stopped. So let me look into now mass spectrophilic aliphatic ketones. So the major fragmentation involves the cleavage of CC bond adjacent to the oxygen atom. For example, if you see here, this is the possible site and this is the possible site adjacent to CC bond adjacent to oxygen atom, molecular ion peaks will be obtained readily in this case. If our group is more than three carbon atoms, longer chain, then macular ferrity rearrangement takes place. So what is this rearrangement, we shall look into it. First as I mentioned, so the cleavage occurs on CC bonds next to oxygen. That means these two are quite possible sites for fragmentation and whether this happens or this happens here or radical would come out and we get acelium ion here. If our group is more than three carbon atoms, that means if you have a longer chain on either side, then macular ferrity rearrangement takes place. What is this one? So here you consider this aliphatic ketone here. This is where the cleavage happens and another possibility is this one and then that leads to the elimination of a ethylene group, ethylene moiety and then the next step is again cleavage can happen here and also cleavage can happen here. That leads to another ethylene and here of course the substituted one. Now we get ethylene and that results in the formation of this unsaturated alcohol radical cation. So this is the macular ferrity rearrangement. This is another possibility provided we have a group which has more than three or carbon atoms. Otherwise in simple cases we have two or less carbon atoms on either side of carbonyl group acilium ion formation takes place invariably in aliphatic ketones. Now let us look into the mass spectrum of four non-n. As I mentioned here, these are the possible sides of cleavage. So now this is the parent ion peak at 142 and due to the loss of a 43 fragment that is what we get is C3 H7 here, H3 is lost here and we get a peak at 99 and then due to the loss of C5 H11 radical 71 unit mass then we get 71 here and also if you lose from here C2 H4 we get a 581. So essentially one can look into all possible fragmentations and we should be familiar with the interpretation in this fashion. So now work out for this also this is not given and just see the difference between these and try to work out what this fragment is due to. So now let us look into mass spectra of cyclic ketones. Cyclic ketones usually undergo beta cleavage. So later hydrogen rearrangement and ethyl radical loss can also happen. Initially what happens beta cleavage happens so that means here cleavage takes place to give a species of this type and then later what would happen hydrogen rearrangement happens hydrogen rearrangement happens so that is the reason this is shown here and then it can form something like this and now again cleavage can happen here to give ethyl radical and then this species here. So these are the possibilities and major fragments one can see or anticipate in the mass spectra of cyclic ketones. You can see here one such example has shown here this is cyclopentanone here mass unit atomic weight is molecular weight is 84 and initially it loses ethyl radical that is 29 to give 55 and then 55 is 84 minus 29 this is what I am referring to and this is initially obtained and then these fragments what happens hydrogen rearrangement happens to give eventually these species. This species although already I have shown in the reaction scheme find out the m by z and then interpret these two as well and what kind of loss in curse here also you can clearly see from this spectrum. So now let us look into the mass spectra of aromatic ketones and here the interesting is molecular ion peak will be obtained readily and again cleavage and macular fruity rearrangement leads to stable ions and provided we have longer carbon chain on the carbonyl group. The aliphatic group if it is longer then you can also see this rearrangement here for example we are considering here this species here in this one two possibilities are there can cleavage can happen here cleavage can happen here you can get this species with m by z value of 105 or you can get m by z value of 120. So that means now we can see 148 is the molecular weight and due to the loss of ethylene you get 120 due to the loss of C3H7 radical you get 105 here. So these two are readily identified from the mass spectrum this is the most common way of fragmentation in case of aromatic ketones. So now let us look into the mass spectra of aliphatic aldehydes and here molecular ion peak is quite detectable but often difficult to see and hydrocarbon pattern is more dominant with longer chain molecules that means when you have a longer chain aldehydes the spectrum resembles that of a longer chain hydrocarbon saturated hydrocarbon and what are the fragments one can see are listed here you can see m minus one peak that is due to the hydrogen loss or m minus 18 due to the dehydration that means due to the elimination of a molecule of water and then one can also see m minus 28 ethylene elimination this is water elimination and this is hydrogen loss and then m minus 43 is due to the loss of CH2CHO or CH2CHOH and then at 44 also one can see CH2CHOH some of these loss can show m minus 43 are more here. So a typical mass spectrum of known and all is shown here you can see it is a longer chain is there it can once the fragment comes out it looks like almost similar to those of long chain saturated hydrocarbons here this is the base peak 142 and then loss of water one can see here loss of ethylene one can see here or loss of CH7H14 one can see here or CH7H15 one can see here so here the loss of 43 and here loss of 44 not loss of see CH7H14 this is the peak due to CH7H14 and peak due to CH7H15 loss of either minus 43 so something like this or this one 44 so either due to the loss of CH2CHO this is 43 or CH2CHOH44 so this peaks 44 in this one and then this one here. Similarly again you can also see at 44 here it almost like a base peak here CH2CHOH so now the mass spectra of aromatic aldehydes we can see and here large m biradical peaks are characteristic of aromatic aldehydes m minus one peak may be larger than m here so molecular ion peak is detectable but often difficult to see again hydrocarbon pattern is more dominant with longer chain molecules then here m minus one peak which can eliminate CO2 give say phenyl radical which in turn eliminate CH2CH2 to give C4H3 so that means seeing this kind of quite common and also elimination of CO is quite common and also one can also see due to phenyl radicals which again eliminates ethylene group to form C4H3 plus cation. So now let us look into mass spectra of carboxylic acids electron impact of carboxylic acid produces molecular ions of moderate abundance so ions corresponding to either COOH plus that is m by z is 45 or the loss of radical like COOH minus m minus 45 are usually observed in case of carboxylic acids and OH and H2O losses are more common from aromatic acids here. When conditions are again favorable carboxylic acids maclaferty rearrangement gives abundant fragments here. So now let us look into the mass spectra of carboxylic yesters and here the fragmentation roots are characteristic of both ethers and ketones whatever we come across in case of ethers as well as ketones can be anticipated together in the mass spectra of carboxylic yesters fragmentation roots are characteristic of both ethers and ketones here and molecular ions are often very weak and the characteristic ions are formation of RCO acylium ion at m by z equals m by z that is m minus 31 if R equals CH3 if you are considering R equals CH3 and then CH2 CH2 COOR formation at m by z equals 87 again if R is a methyl if it is a methyl yester and then other possibility is this one m by z equals 74 again for methyl yesters this is CH2 CHCO CH3 and OH again it is a methyl yester. So when we have a methyl yester this is the typical characteristics of the ions during the fragmentation okay one is acylium or it can form something like this again with methyl yester if it is and then because methyl is shown here and again if it is a methyl yester here this is a 74 one. So now let us look into methyl actonate RCO m minus 31 you can see 58 is here and then 58 158 is there 127 31 so you can see here acylium ion formation is there and then C5 H11 loss then 87 it comes here due to this one and then 74 is there again if it is for the methoxy so C6 H12 loss is there and you get this one so that you can readily identify from these things and also of course at 59 this is the one we have seen. Now you can also make an attempt to see what is this one what is this one as well and what is the loss approximately so that gives some idea about interpretation. Now let us look into aromatic estus here acetate groups are readily eliminated neutral ketones and acylium ions are often observed here and then a typical example is considered here nitro phenyl acetate in case of nitro phenyl acetate mass is 181 and first we will see NO2 loss to give that is m minus 42 that is at 139 and then we will see at 123 and then we are also seeing something at O this is due to this one here and this is another one one can see. So this is the typical fragmentation of aromatic estus here so in aromatic estus the possible cleavage site initially is this one the OC bond next to carbonyl group. So now let us look into aliphatic remains fragmentation occurs predominantly by radical cleavage to generate iminium ions here and you consider again the possible cleavage site is this one and R would come out and then we get something like this this is iminium ions so this is the characteristic of aliphatic remains fragmentation and then cleavage can be at R1 R2 loss of the largest branch is preferred if the branch is if the aliphatic branch is the largest one the one that is very largest is the preferred site for cleavage of radical cleavage the product ion undergoes further fragmentation involving hydrogen migration to generate a second iminium ion species for example this is the first one and first one what happens if further undergoes through hydrogen migration to give a ethylene radical ethylene cation and then this gives the second iminium ion. So this is the typical fragmentation of aliphatic remains what would happen to aromatic remains yes I will show you here these are the aliphatic remains these are the possible sites and this one for hydrogen migration and to generate second iminium and then you can see here the molecular weight is 101 first it loses methyl groups to give 86 and then it can also lose an ethylene radical to form 72 here and now you work out what is the m by z corresponds to which species you work out for 58 and also here again between them there is a 44 is the probably CH2 goes up you can just look into it for example if you look into 72 minus 58. So this is also 14 that means here 114 m minus 14 and m minus 14 is there then you identify those from these fragments that I have already shown in these reaction schemes. So now let us look into aromatic remains intense molecular ion peak is observed that is very essential loss of one of the amine hydrogen leads to the formation of m minus 1 peaks loss of a neutral HCN group followed by loss of a H results in the prominent peak of m by z equals 66 that is due to C5H6 radical or 65 is C5H5 radical. So these are the possible cleavage sites and this can also possible to give initially m minus 1 and then a typical aniline spectrum is shown here you can see 93 is the weight but first it loses 1 to give 92 and then one HCN is lost to give 66 here. So now look into the preferred cleavage here as I said if we have again longer chain is there preferred cleavage will be here and it leads to the elimination of a CH2R radical and formation of again iminium species you can see here and this 135 CH3 goes and you can get this iminium species here and I think this would do this is about ferrocinium species acyl compound of ferrocene you can see very clearly here mass spectra is given here and this is 100% abundant and try to analyze the spectrum of mass spectrum of ferrocene having acyl group on each cyclopentadienyl group and then all the data is given try to analyze and also this is the value obtained from simulation I have provided this information also now try to analyze this one in a very systematic way the way I did for previous examples of organic molecules and then in my next lecture I would come up with more examples in organic compounds and also having halogens that is very very important also very interesting until then have an excellent time. Thank you.