Predict the products of the following reactions.
An excess of ac...

Question

Predict the products of the following reactions. 
An excess of acid is available in each case. 
(a) ethoxycyclohexane + HBr 
(b) tetrahydropyran + HI
(c) anisole (methoxybenzene) + HBr

Accepted Answer

Hey everyone and welcome back in today's video, we are going to solve the following problem. Should the products expected from the reactions given below a meth oxy cycle Benzene reacting with excess of hydroponic asset. B. I's Oprah poxy Benzene reacting with excess of hydroponic asset. And see tetra hydro ferrin reacting with excess of hydro biotic asset. If we start with a we will simply draw the reaction scheme. Meth oxy cycle of fencing essentially implies that we have a five member drink cycle fencing and a meth oxy group bonnet sits at I B O C string. It reacts with excess of hydroponic asset and we may simply think about the mechanisms to solve this problem properly, the lumpy on oxygen will get protein ated easily because we're adding a strong asset. So it will attack that acidic hydrogen and we will have the loss of the leaving group which is bromide. In this case we will form a protein ated intermediate which is now a good leaving group, right? We have a formal positive charge on oxygen. Now it's a very good leaving group because it's positively charged in the next step of the reaction. The bromine and I informed in the first step acts as a nuclear file and it will attack that third, that secondary carbon atom. Right? Essentially, we have a nuclear attack over here at that position, followed by the loss of the leaving group. So the elections here will be transferred on oxygen in the form of a lone pair and during this nuclear attack stop, we are forming two products, One of them is bromo cyclo insane. So that's our first product plus methanol so far. However, it's important to understand that we're using access of hydroponic asset. What that means is the alcohol here can participate in the reaction further. The lone pair on the oxygen can be participated once again. So it's attacking hydroponic asset. The acidic proton is abstracted. We have the loss of the leaving group and we are forming a protein ated intermediate. So we're going to say that The next step is the protein nation step and we are forming CH three oh age To Ride two Protons cause of charge. Now this is where again the reaction can repeat itself so that the bromine and iodine that we formed in the previous stuff can act as a nuclear file and it can attack that electro fill a carbon atom in an essence the reaction manner followed by the loss of the leaving group which is water. So we may now notice that we are going to form method bromide CH three ch three br. In addition to that we are forming water because that's our leaving group. And if we add the previous structure form como cyclone fencing. Those would be our three products formed in this reaction whenever we are treating meth oxy cyclone fencing with excess of hydroponic asset. So we may label these as our final three products. Now if we continue and look at barbie for B. We are starting with eyes open epoxy benzine. So that means we are going to draw a benzene ring. Oprah poxy means that we are bonding oxygen to that branched al kill chain containing three carbon atoms. Right is Oprah poxy according to the problem, we're treating it with an excess of hydroponic asset. So we may say we are adding hydro bro Marcus said. And just as before. The first step is the nuclear attack stop. So the lone parent oxygen gets protein ated followed by the loss of the leaving group. And we are forming a protein ated intermediate with a former positive charge. And now the bromide and ion formed in the previous stop will act as a nuclear file. However, it cannot cannot attack that position because it's an sp two carbon atom. So the only sp three carbon atom that can be attacked is this electrostatic position over here. So the negative charge will attack that position for by the loss of the leaving group. We are going to form Our two products. And we may say that the first product is Fennel and the second product that we are forming is an isopropyl group and it has protein bonnet set. These would be our two products and we are done. Now let's think why this reaction cannot proceed. Further notice how previously said that the alcohol can react with another equivalent of hydrochloric acid and therefore we would produce an al kill hey light. This is not possible here because the attack would require us to attack that sp two carbon. And this is not really possible recall that An essence reaction requires an sp three hybridized carbon atom. While this carbon is sp two hybridized. That's why the bromine and ion would not attack this position. And these will be our final products. We don't need to worry about any additional steps. If we look at reaction. See now tetra hydro ferrin reacting with an excess of hydro biotic asset. So we are going to draw that's your hydro Furin. We're carbon atoms oxygen. So that's a five member ring that has oxygen and four carbon atoms access of hydro biotic asset. Similarly to the previous steps because hydro biotic acid is a strong asset, it can easily donate that acidic proton to the lone pair of oxygen. So we have that proto nation stop followed by the loss of the leaving group. And we are forming our protein ated intermediate. Now the iodide ion that has been formed can act as a nuclear file. And this can attack any of the two positions that are equivalent to cheddar because the molecule is symmetrical. So let's suppose that we are taking this position and then this is followed by the loss of the leaving group. Right? We are forming our first products. So we may say that we are opening that ring because we are taking it over here and then we have the loss of a wage. So we're going to draw a four member chain for carbon atoms at position number one we have an O. Age group And at position number four we are adding iodine. Now let's think about it. This is our first product, right? And we also want to think what's happening next. We can perform our protestations stop once again because there's a lone parent oxygen that will get protein ated by another equivalent of hydro biotic asset. We may now drew our protein ated intermediate H20 with a formal positive charge for carbon atoms. iodine. And now this is a good leaving group. This is an sp three hybridized carbon atom. So the iodide iron that has been formed might act as a nuclear file at that center in an essence to reaction. So we are attacking the electra Philip position and we have the loss of the leaving group to form our final products. We may say that the first product form this water because we have a loss of water plus the substrate will have four carbon atoms. So we may draw 1234 carbon atoms with two iodine atoms bonded two terminal positions. Right? So that will be our final products. We may say that these Our our final products for the 3rd reaction. Now we have got our products for A. B and C. And if we look at these products, we may simply conclude that the correct answer choice to this multiple choice question is C. However, if you have any questions, don't hesitate to leave your comment down below in the comment section and thank you for watching.

Predict the products of the following reactions. An excess of acid is available in each case. (a) ethoxycyclohexane + HBr (b) tetrahydropyran + HI (c) anisole (methoxybenzene) + HBr

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