Exam (elaborations)
chem 219 module 5 Test with Questions Solved 100% Correct | Latest Update
- Course
- Institution
chem 219 module 5 Test with Questions Solved 100% Correct | Latest Update
[Show more]
Seller
Follow
Content preview
chem 219 module 5 Test with QuestionsSolved 100% Correct | Latest Update
What is necessary about the R and R' groups of a Williamson Synthesis in order
for their to be a higher yield of product? - ✔✔The R' group would need to
have a smaller steric bulk (primary or secondary), which would allow for the SN2
mechanism in the second step. If the R' group is sterically bulkier than the R
group, it would have to go through an E2 mechanism which would have a smaller
yield of product.
what does "unhindered" mean? - ✔✔Less sterically bulky (primary
or secondary strucutres)
Although mostly inert, ethers can be forced to react under very specific
reaction conditions (typically harsh/extreme conditions). The typical mode of
reaction of an ether is .....? - ✔✔Cleavage
What is the cleavage reaction of an ether?
What type of molecule is used to perform the cleavage? - ✔✔Breaking apart
of the ether by severing a C-O bond of the ether by an HX.
Typically, ethers react with strong acids and heat to undergo cleavage.
,If the alkyl groups of the ether are unhindered, what mechanism will be used
to sever the C-O bond? - ✔✔The C-O bond can be broken by reaction with a
halogen nucleophile in an SN2 reaction after protonation of the ether oxygen
What happens during a cleavage reaction if the alkyl groups are unhindered? -
✔✔The halogen bonds to the less-hindered R group (creating the alkyl halide),
and the oxonium ion is displaced to form an alcohol (containing the larger, more-
hindered R group).
What happens during a cleavage reaction if the alkyl groups are hindered
(tertiary)? - ✔✔If the alkyl groups are bulky/sterically hindered (tertiary), the
ether typically cleaves by an SN1 mechanism, as these groups can form the
stable carbocation intermediate that defines the SN1 mechanism. In this case,
the ether oxygen atom remains with the less-hindered alkyl group and the halide
bonds to the more-hindered alkyl group.
What are the initial products of the cleavage of an ether using HX? What happens
is excess HX is present? - ✔✔The initial products of the cleavage of an ether
using HX are one equivalent of alcohol and one equivalent of alkyl halide.
If excess HX is present, the alcohol formed via cleavage may react to form another
equivalent of alkyl halide. Cleavage reactions can be used to help determine the
structure of complex, naturally occurring ethers because the products of the
cleavage reaction are smaller and more easily analyzed fragments. Working
backward from the fragments, the structure of the original ether can be deduced.
What is a peroxyacid (or peracid) and what is it used for? - ✔✔A peroxyacid is
analogous in structure to a carboxylic acid but contains an extra oxygen between
the carbonyl and hydroxyl group.
, A reagent used to synthesis epoxides from alkenes.
What happens during a epoxidation reaction? - ✔✔An alkene reacts with
a peroxyacid to form an epoxide.
- an oxygen is transferred from the peroxyacid to the alkene
- the C=C p bond is broken and incorporates the oxygen atom as part of a
three-membered ring.
Why are epoxides more reactive than ethers? - ✔✔Due to the significant
amount of ring strain in epoxides, they are much more reactive than regular
ethers and undergo reactions through opening of the three-membered ring.
What is a common way to open the three membered ring of a epoxides? -
✔✔Treat the molecule with aqueous acid (a mixture of acid and
water).
What happens during a reaction between epoxides and aqueous acid or alcohols?
What is the product? - ✔✔- initial protonation of the epoxide oxygen
- followed by a nucleophilic attack of water on one of the epoxide carbons
- SN2 where the leaving group remains attached to the other carbon atom of
the original epoxide ring
The product of an acid-catalyzed ring opening of an epoxide is a diol, specifically a
vicinal diol (two hydroxyl groups on adjacent carbons).
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller KenAli. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $13.24. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
75632 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now
