Learn about Organic Chemistry 13, in this comprehensive video by bannanaiscool.
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Male Speaker: Organic reactions, there are about four different ones that play a major role in organic chemistry and these are ones you got to know, so here there are. The first type is called substitution and here is what substitution occurs when. By the way substitution reaction about 200 years ago, may be about 170, work really a major way that chemists finally determined how not just reactions take place in organic chemistry but in chemistry in general they were always just trying to figure out how to derive formulas properly for different types of reactions and organic chemistry held the key because this type of reaction called substitution which only happens with that you have to be concerned with. Alkanes and benzene rings, so substitution occurs with those two types, with that aromatic. Here is how it operates. Substitution means quite simply when these molecules combined with reactions occur because molecules collide with one another and so if you have a molecule here, two carbons belong to single bond that's ethene, right, so ethene reacts with bromine, lets say liquid bromine and we could put that subscript there but I am just lazy right now. So, here we got ethene reacting with bromine, collision theory tells that it collide with right amount of activation energy we are going to get reaction that takes place and it might be catalyzed by certain things here and might be at elevated temperature situation as well in order to create reaction. What's going to happen, you are going to get substitution where a hydrogen here is going to bump into a bromine and the bromine one of the bromines is going to switch places with the hydrogen, and that's how you are going to get quite simply is there is an ethene with a bromine on there instead. What comes of hydrogen when attaches to the other bromine all the other hydrogen so you get HBr and so now we get two products that's just hydrogen bromide, whets that right there, and look at it, its ethene with bromine and its bromoethene. Right substitution, you look at that, this too hard man what well because look I cant tell what that is, I love when you get a condensed structure of formula like that you might have to draw it out to make sure that it has got multiple bonds or not and look when you do this one CH3, CH2, CH2, CH3 is saturated, that is quite simply butane. So, when butane collides with chlorine you can get a couple of things happening right neither than it would be wrong if you predicted them to happen but you just have to make sure that you state it properly on an exam. So, if your teacher is going to say what forms, all these forms you are going to go that right there and you are going to put chlorine down there. What if you put the chlorine on the second carbon, well then it would be a 2-Chlorobutanes that have a chlorobutane or 1-chlorobutane. Well, that's perfectly, that's okay, hydrogen chloride also forms in that substitution reaction. Its okay to say which one does which or it's okay to actually say that it's either one or a two that's okay. So, as long as you get the idea that it is substitution and you are going to have to take and put one cl alone and one off. Okay, that's the same one, take a h out, put a cl on. Now, look at this one, C6H6 plus I2, wow what is that, I have to draw it out and you have just got to remember that C6H6 tells you right away that's benzene and so really that is this. Right, a benzene ring and if you are going to do substitution the benzene ring has hydrogens and everyone of these little points here which are carbons and if a collision occurs it usually is a substitution of an h with in this case is I, you can put I on anywhere you want plus HI, hydrogen iodide comes off and what would that be well that's an iodo on a benzene that's iodobenzene.