For each reaction, give the expected substitution product, and...

Question

For each reaction, give the expected substitution product, and predict whether the mechanism will be predominantly first order (SN1) or second order (SN2).

d. cyclohexylbromide + methanol

e. cyclohexylbromide + sodium ethoxide

Accepted Answer

hey everyone. The problem reads for each reaction predicted type of mechanism through which it will proceed either SN one or SN C and write expected substitution products. There's also a small hint for us that one of the factors in determining the order of the reaction is the strength of the nuclear file. Strong nuclear files encourage essential reactions and weak ones promote sn one reactions. Now let's start with a problem. A problem a We have a reaction between third beetle bromide and water so hour ago is to ride the chemical formulas for these two compounds. We will start withdrawing third beetle bromide and reacted with water. Now we have to determine which of the two is our nuclear file. We call that nuclear files either have a source of non bonding electron pairs or a negative charge. Which implies exactly the same thing. Specifically in this case the first compound must be our substrate because it has a good leaving group which is booming Calleja. That said we can classify it as our substrate, which implies that the remaining substance or water must be the nuclear file. And that actually makes perfect sense because we have non bonding electrons around oxygen. Now, what can we tell about our nuclear file? We can immediately tell that it's weak And the reason for that is because its molecular it doesn't possess any charge. It exists as a single molecule. And because it's a weak nuclear file uh simply based on the given hand, we can tell that this reaction would be an sN one reaction since we have water acting as a weak nuclear pile. Now, we can actually confirm that. Looking at the nature of the substrate, the substrate here is a territory substrate because it has a carbon atom with three neighboring carbons. Now, if this is an SN one reaction, all that we have to do now is to predict the products of this reaction. Recall that the first step in an sN one reaction is the formation of the carbo Karen intermediate. So we have a loss of the leaving group in this case bro mean and we are forming a stable tertiary carbo Caroline followed by the nuclear felt like a tag step. And then you can feel like a tag in this case, Each two or water attacks the car bull cast iron. And we're forming a protein ated intermediate. That protein ated intermediate later on will be D protein ated by either the bromide and I informed during the first step or another water molecule. So we can use a shorthand notation and immediately say that. Okay, we will finally D protein ate that and we will form our final product for the first part. Our final product will have oxygen bonded to that electra Felix center with only one age remaining because one of the two was already removed by I had water or bromide. This is third pizza. No. And it's the first substitution product that we're interested in for this problem. Now using exactly same logic, we can think about our second reaction. The second reaction is a reaction between one chloral hexane and sodium with oxide. So what we're going to do now folks, we're going to draw the first structure which is one chloral hacks and we can do that by drawing a six carbon chain And also attaching chlorine to position number one. So we will add one more bond to indicate the presence of chlorine. The next substance in this reaction is sodium meth oxide, Which is NAO CH three sodium bonded to Miss Oxide. Now thinking about it, we can immediately it and follow our substrate, which is the first compound to you to the same reasons as before. We have a good leaving group which is a halogen in this case chlorine. What can we actually tell about the substrate? This is a primary substrate because the leaving group is bonded to a carbon atom that only has one neighboring carbon, logically thinking the remaining one must be our nuclear file. But we call from general chemistry that This is an ionic substance, it has a group. one, a elements in it. What that means says we have to disassociate it since ionic soluble ionic substances associate in solutions. So we have sodium myth oxide associating into sodium cat ions and meth oxide and ions because sodium is famous for being an ion spectator. I'm not really worried about sodium in this case, I'm primarily interested in meth oxide itself, which will act as a nuclear file because it has a negative charge on it. Knowing that meth oxide is the actual nuclear Islanders reaction. I can also classify it as a strong nuclear file since it's charged. And finally because it's a strong nuclear file, I can immediately tell that this is an essence to reaction due to the fact that sN two reactions are favored by strong nuclear files. My last step is to predict the actual substitution products and to do that, I can recall the steps of an essence to mechanism and listen to mechanism proceeds in a way such that the strong nuclear file in this case meth oxide attacks the electra Felix center and simultaneously we have the loss of the leaving group. So summarize we're simply replacing the original glory in group with meth oxide. So to draw the substitution product, I'm going to draw the original six member chain and now instead of C Cl bond or carbon chlorine bond, I'm going to add carbon meth oxide bond. Now this is the final product for reaction be. And what we can also tell Is that this compound is called a one meth oxy hexane. Now let's summarize our findings for a the final product that we formed Wise 3rd beats and all. And the reaction pathway was sn one for B. The final product was one myth. Oxy hacks formed in an essence to reaction. These are our final answers. If you feel you have any questions, feel free to leave them down below. I hope you enjoyed this video.

For each reaction, give the expected substitution product, and predict whether the mechanism will be predominantly first order (SN1) or second order (SN2).
d. cyclohexylbromide + methanol
e. cyclohexylbromide + sodium ethoxide

Key Concepts

Nucleophilicity

SN1 vs. SN2 Mechanisms

Substrate Structure

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