Video Solution: Each of the following reactions has been described in the ch...

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Organic Chemistry / Leaving Group Conversions - Using HX / Problem #15921

Each of the following reactions has been described in the chemical literature and involves an organic starting material somewhat more complex than those we have encountered so far. Nevertheless, on the basis of the topics covered in this chapter, you should be able to write the structure of the principal organic product of each reaction. 

Video Transcript

Hey everyone's, let's take a look at this question here we have a benzene with two substituents coming off of it reacting with HBr and heat, so I want you to pay attention to is the two alcohol groups that we have, we have one right here and another one located down here. Now, alcohol is not a good leaving group but we know when we subjected to HX we can convert it into a good leaving group and then our reaction can go forward from then. Now, here these alcohols are, are they primary, secondary or tertiary because that's going to predict what kind of mechanism we're going to undergo. Well, both of these alcohols are in fact primary, this one's primary and this one's primary, because all this looks like is if we draw in without our atoms being shown is we simply have a CH2, CH2, OH and down here another CH2, CH2, OH, right? now using HBr that's going to be a strong acid and what that's going to do is it's going to first protonate both of our alcohols and turn them into good leaving groups, so this one's going to become a water and this one will become a water as well, with a positive charge. Now, we would actually undergo an SN2 reaction because what we have is a primary leaving group, so it's going to have a great back side. if this was a tertiary leaving group we would be more likely to do an SN1 because we form a stable carbocation. So, in our next step all is going to happen if we're simply going to have bromine around and what that's going to do is simply do an SN2 reaction on both of these waters, so we expect to get as our final product if we redraw this, if you would get 2 different substitutions occurring, here you have a CH2, CH2 and then Br, right? And same thing down here, here we would have another CH2, CH2 and then Br, okay? And this right here is going to be our final product, alright? and just remember that this proceeded through an SN2 mechanism. Alright because we had a primary alcohol to begin with. Alright, so I hope this made sense and let me know if you guys have any questions.

Treatment of alcohol A with HCl (catalyst) in CH3OH as the solvent produces 3 different polyenes B, C, and D that have the same molecular formula (MF= C9H16O) and contain only trans alkenes. Predict the structures of B, C and D.

b.  Which one of the alkenes B, C, D will be favored under thermodynamic or kinetic control? Explain your answer in 1-2- sentences.

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Predict the organic product of the following reaction. When appropriate, be sure to indicate stereochemistry. If more than one product is formed be sure to indicate the major product. Draw your answer in skeletal form. You will be graded on the product your draw from the reaction no other information is needed for this question.

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Predict the organic product of the following reaction. When appropriate, be sure to indicate stereochemistry. If more than one product is formed be sure to indicate the major product. Draw your answer in skeletal form. You will be graded on the product your draw from the reaction no other information is needed for this question.

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Predict the major product for the following reaction

A) I                             B) II                            C) III                          D) IV                          E) V          

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Provide an organic reaction in which the given intermediate or transition-state structure is involved and give a chemical equation for your selected organic reaction that includes the following in each of your answers:

(i) structural formula(s) for the organic reactant(s) [Be sure to show stereochemistry clearly when necessary.];

(ii) a structural formula for the major organic product [Be sure to show stereochemistry clearly when necessary.];

(iii) the experimental conditions (Give structural formulas for organic compounds. Give a chemical formula for inorganic reactants or catalysts . If heat and/or light is needed, be sure to indicate it appropriately.) As we do for most organic reaction equations, the chemical equations that you give do not need to be balanced. Be sure to show stereochemistry clearly when necessary.

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Give the best reagent(s) for the following reactions to occur (in the box). Include solvents if applicable. Indicate the reaction type (ex. SN2) on the line next to the product. Indicate the reaction type (ex. SN2/E2/SN1/E1) on the line next to the product box.

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The transformation of the hydroxyl group into a good leaving group can be accomplished through the use of various reagents. 

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Provide a complete mechanism for the following transformation.

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Predict the major product of the reaction shown.

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Compound A reacts with HBr via an SN1 process leading to 3 different constitutional isomers. Draw the structure of these products.

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The following reaction below is probably

 

A) an SN1-type reaction involving the protonated alcohol as the substrate.

B) an SN2 -type reaction involving the protonated alcohol as the substrate.

C) an E1 -type reaction involving the protonated alcohol as the substrate.

D) an E2 -type reaction involving the protonated alcohol as the substrate.

E) an epoxidation reaction.

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