[theanonymous]

My organic chemistry 1 teacher isn't the best organic chem teacher you could ask for - he's way too smart for our class and he doesn't cover the basic stuff for Organic Chemistry 1. So now, Organic Chemistry is absolute hell for me.
There are about 150 students in our class - and guess what the average was for the 1st test? A freaking 31%. Yes, 31 out of 100... 150-200 students. 31% -.-

Right now, I'm panicking because the end of the semester is almost here and we have one more exam left to take.
My homework grades is the only thing that's supporting my grade for this class, but they're so hard. I'm an excellent note taker as well (an active one) and I have never in my entire life made a 22% on a test.

Anyways, the first question I have is here:

1. 2-Butyl alcohol is converted to 2-butyl bromide upon treatment with aqueous HBr at elevated temperature. Please describe two experiments/measurements you could make to determine whether the reaction proceeds via an Sn1 or an Sn2 reaction. (Assume that it is one or the other, not both.)

What am I supposed to do? Write the reaction???
Does it look like this: http://www.imagebam.com/image/ea98fe215480338
If so, what do I do next?

It says "describe two experiements/measurements you could make to determine whether the reaction proceeds via an Sn1 or an Sn2 reaction" though (?)

*delete me*

[sjb]

My organic chemistry 1 teacher isn't the best organic chem teacher you could ask for - he's way too smart for our class and he doesn't cover the basic stuff for Organic Chemistry 1. So now, Organic Chemistry is absolute hell for me.
There are about 150 students in our class - and guess what the average was for the 1st test? A freaking 31%. Yes, 31 out of 100... 150-200 students. 31% -.-

Right now, I'm panicking because the end of the semester is almost here and we have one more exam left to take.
My homework grades is the only thing that's supporting my grade for this class, but they're so hard. I'm an excellent note taker as well (an active one) and I have never in my entire life made a 22% on a test.

Anyways, the first question I have is here:

1. 2-Butyl alcohol is converted to 2-butyl bromide upon treatment with aqueous HBr at elevated temperature. Please describe two experiments/measurements you could make to determine whether the reaction proceeds via an Sn1 or an Sn2 reaction. (Assume that it is one or the other, not both.)

What am I supposed to do? Write the reaction???
Does it look like this: http://www.imagebam.com/image/ea98fe215480338
If so, what do I do next?

It says "describe two experiements/measurements you could make to determine whether the reaction proceeds via an Sn1 or an Sn2 reaction" though (?)

*delete me*

What are the differences between S_N1 and S_N2 reactions? Can you write complete equations, including intermediates for both? You've made a good start in your depiction of the alcohol - there seems to be something you have added to that that is missing from your bromide.

[theanonymous]

What are the differences between S_N1 and S_N2 reactions? Can you write complete equations, including intermediates for both? You've made a good start in your depiction of the alcohol - there seems to be something you have added to that that is missing from your bromide.

That's the thing...I have absolutely no idea where to go from there!
That's all I have in my notes for 2-butyl-alcohol.

[theanonymous]

Here's another page of my notes:

http://www.imagebam.com/image/49aabf215486613

Is the answer basically..." Treating 2-Butyl alcohol with SOCl₂ and PBr₃"?

[Dan]

That's all I have in my notes for 2-butyl-alcohol.

If you are not prepared to read beyond your notes, then I promise you will fail. I'm not trying to be nasty, just realistic. You cannot pass a chemistry course without opening a book.

Get yourself a couple of organic chemistry textbooks from the library. My personal recommendations would be Clayden/Greeves/Warren and Sykes (for other recommended texts click here). Read and make additional notes on the chapters dealing with nucleophilic aliphatic substitution.

Hint: What factors affect the rate of S_N1 and S_N2 reactions? Think about the differences.

[Babcock_Hall]

Do you understand where the names S_N1 and S_N2 come from?  That would be a good place to start.  Also, is carbon-2 of the reactant and product a stereogenic center or not?  Your drawing of the product does not make this clear.

[theanonymous]

This is hopeless..
I have my textbook right in front of me (Organic Chemistry 8th Edition Francis A. Carey Robert M. Giuliano) and I'm reading the chapter where I should be finding an explanation to all this but I feel like it's all fluff.
My teacher literally did /not/ go over the fundamentals of organic chemistry, he just dove right into the hard stuff - or the "stuff that really matters." I'm doing the best I can to keep up with him by looking up explanations online and I'm struggling to find something that's actually substantial!

[discodermolide]

Don't cry. Start reading at the first page and finish with the last page.
I'm sure you can find some web sites with easy explanations to the fundamentals.
By the way; what, for you, are the fundamentals?

[theanonymous]

Hint: What factors affect the rate of S_N1 and S_N2 reactions? Think about the differences.

Alcohol structure has an effect on reaction rate

S_N1 - a unimolecular reaction (only one thing undergoes a chemical change); tertiary and secondary carbocations
S_N2 - a bimolecular reaction (two things undergoe a chemical change; methyl and primary carbocations

?

[discodermolide]

What don't you understand in that quote?
Unimolecular, bimolecular, carbocation. If you don't tell us exactly what you don't get how can we help?
One question at a time, it makes it easier for everyone to understand.

[DrCMS]

There are lots of web pages describing S_N1 and S_N2 reactions - try looking here http://en.wikipedia.org/wiki/SN1_reaction and http://en.wikipedia.org/wiki/SN2_reaction

Look at how the stereoselectivity is different for S_N1 and S_N2 and look at what favours each.  Now try answering your own question again.

[theanonymous]

Discoder...
I don't understand how to go about answering this question:

2-Butyl alcohol is converted to 2-butyl bromide upon treatment with aqueous HBr at elevated temperature. Please describe two experiments/measurements you could make to determine whether the reaction proceeds via an Sn1 or an Sn2 reaction. (Assume that it is one or the other, not both.)

I also don't understand how my teacher expects us to know how to think abstractly in an intro course to Organic Chemistry when we have no basis for the stuff we're doing now
For example, knowing the structure for 2-Butyl alcohol, 2-butyl bromide, etc etc, arrow pushing mechanisms, etc etc, electron flow, etc etc. All the little stuff that my teacher never elaborated on or explained clearly enough. I don't want to make it seem like I'm complaining about how miserable I am with Organic Chemistry. I'm DESPERATELY trying to piece all this together because I'm such a logical thinker. My teacher makes it all abstract and vague and I'm struggling.
This particular problem is something I don't get because it's no where in my notes and it's no where in my book AND I've also searched online!

I don't know if he's pulling these weird questions out of his head or something but I have absolutely no idea how to approach this question... hence me being here seeking help. I don't want to come across as rude or needy, I'm just trying to make sense of it all.

Ultimately, my teachers inability to provide us with sufficient information BEFORE assigning us extremely complicated/vague homework problems to tackle is what's frustrating me the most.

[discodermolide]

Hint: What factors affect the rate of S_N1 and S_N2 reactions? Think about the differences.

Alcohol structure has an effect on reaction rate

S_N1 - a unimolecular reaction (only one thing undergoes a chemical change); tertiary and secondary carbocations
S_N2 - a bimolecular reaction (two things undergoe a chemical change; methyl and primary carbocations

?

Right according to your definition above the conversion of butane-2-ol to 2-bromobutane must be a unimolecular process. That is S_N1.
So what do you think is the mechanism for this reaction, what happens first?
Read this page carefully:
http://en.wikipedia.org/wiki/SN1_reaction

Google SN1 reaction conditions and see what you get

[theanonymous]

There are lots of web pages describing S_N1 and S_N2 reactions - try looking here http://en.wikipedia.org/wiki/SN1_reaction and http://en.wikipedia.org/wiki/SN2_reaction

Look at how the stereoselectivity is different for S_N1 and S_N2 and look at what favours each.  Now try answering your own question again.

What whattt???
It says "Please describe two experiments/measurements you could make to determine whether the reaction proceeds via an Sn1 or an Sn2 reaction."
??

[theanonymous]

Hint: What factors affect the rate of S_N1 and S_N2 reactions? Think about the differences.

Alcohol structure has an effect on reaction rate

S_N1 - a unimolecular reaction (only one thing undergoes a chemical change); tertiary and secondary carbocations
S_N2 - a bimolecular reaction (two things undergoe a chemical change; methyl and primary carbocations

?

Right according to your definition above the conversion of butane-2-ol to 2-bromobutane must be a unimolecular process. That is S_N1.
So what do you think is the mechanism for this reaction, what happens first?
Read this page carefully:
http://en.wikipedia.org/wiki/SN1_reaction

Google SN1 reaction conditions and see what you get

OH is displaced by Br (the nucleophile)?