Hello YouTube viewers, the topic of today's video is the study of IR spectra. So in this video I am going to explain how you can study the IR spectra, how you can interpret the IR spectra, how you can understand the IR spectra. So first of all what you need to do you have to just memorize these values. The OH bond gives the wave number between 3200 and 3650. Similarly the other functional groups gives the wave numbers according to the wave number. their vibrations okay so now moving on so this is the first spectra that is of decaying so how you can understand that this spectra is of decaying first of all you know that sp3 ch stretch the ch stretch of sp3 occurs at about 3000 so whenever there is a peak at 3000 it means that there is an sp3 ch present in our given molecule okay and and this sp3 ch is it a ch2 or is it a CH3?
How you can find it? You can find it by looking this here. Okay. As you can see here that we have got a CH2 band and then we've got a CH3 band.
Okay. So this means that in our molecule we've got a CH3 and we also have got a CH2. So this is an indication of a presence of a straight chain compound.
So I can say that this compound here is decane and decane has a formula of CH3, CH2, 8 and CH3. Okay. So this is the indication of the decay and this peak here shows that it is a long chain compound.
Moving on towards the next example. The next example, as you can see here, what we've got is SP3CH peak. OK, so as I've just told you earlier that at 3000, if a peak occurs at 3000, it means that this peak is of SP3CH stretch.
OK, and secondly. What I have to do, I have to find that if there are CH2 group or the CH3 group. So this peak here indicates that there is a CH2 bend and there is no CH3 bend.
As compared to the last example, let me just compare it with the last example. As you can see in the last example, we have two peaks. In the last example, we had two peaks.
One was that of CH2 and the other one was that of CH3. But in case of CH3. This example this new example in case of this new example we only have got one peak of CH2 and again we do not have any long chain representation here.
Okay so this means that our given molecule contains only CH2 and all the CH bonds are sp3 hybridized. So that means that our compound can be a cyclohexane. Okay so this gives an indication of the presence of cyclohexane. Okay so now moving on towards the next example. So next example this next example is that of an alkene okay so here it is a double bond okay this is a double bond actually this is there is a misprint and there is a double bond and the next thing is that this is actually cis2 pentene okay this is actually cis2 pentene and the as we have got a peak at 3000 which indicates the presence of sp3ch stretch and again we have got a higher peak of sp2ch stretch okay so we have got two types of peak the sp3ch and sp2ch so this means that there must be present there must be present a double bond okay so where is the double bond present the double bond is actually present between this carbon and this carbon okay the double bond is present between these two carbons okay and this peak here indicates that this stretch is the c double bond c stretch is a cis stretch okay that our given compound is a cis isomer okay so now moving on towards the next example The difference between the previous and the next example is just the sys and transform.
So as you can see here that this is a trans to pentene. This is a trans to pentene and the difference is only the presence of this disturbance here. This disturbance indicates the presence of a trans group. This disturbance indicates that our given pentene, our given to pentene is trans to pentene. And this disturbance was not present in previous example.
So as you can see here there was no disturbance here. In the previous example, in case of cis, there was no disturbance here. Okay.
So now moving on towards the next. Okay. So now in case if we have got a C triple bound C.
Okay. If we have got a C triple bound C. So what we've got here that a C triple bound C stretch occurs at roundabout 2200. So we have got C triple bound C stretch at about roundabout 2200. And here as you can see that we've got an SP3C stretch.
And we've got. sp stretch okay sp stretch occurs at around about 3500 and sp3ch stretch occurs at 3000 okay um so now what we have here is that we've got a c triple bond c okay we have got an sp3ch and we've got an spch so another thing is that we also have got a long chain okay so now um this chain here this peak here indicates a triple bond ch bend okay so now you We have got the molecule that is of 1 octane. So these are some of the indications of the graph that tells us that our given molecule is that of 1 octane.
So now moving on towards the next example of toluene. So now again what we have, we have got an sp2, sp3 CH stretch at about 3000. And again we have got an sp2 CH stretch at around about 3100 or 3200. And again this thing here, this. peak this peak here indicates the c double bond c stretch of aromatic c double bond c stretch okay this peak indicates aromatic c double bond c stretch and if we have got these peak here these peak show the mono substitution okay so our result is a toluene so this here is a mono substituted benzene and that is of toluene okay so now moving on again we have got a meta substituent okay we have got a meta substitution so here as you can see we have got a meta solution or so this is the peak for the meta substitution and again these peaks are that of aromatic CWB CCH stretch that so this graph is just similar to that of the before but what we have here is that we have got an aromatic CWB CCH stretch we have got a meta substituent peak and we have got a sp3 CCH stretch as before and we've got an sp2 CCH stretch as just like the before okay and the last thing is that these meta substitutions the metastitute peak okay um just compare it with this we have got this peak this peak is that of the monosubstituted product and this peak is that of a meta substituted okay so guys that was our last example inshallah see you in the next video do not forget to like the video and subscribe the channel if you've got any question you can ask in the comments thank you and allah hafiz