43 Questions
What is the main role of pyridine in the conversion of alcohols to tosylates?
It acts as a base to neutralize the acid formed
What is the abbreviation for the tosyl group?
Ts
What is the pKa value of p-toluenesulfonic acid (TsOH)?
-7
What type of mechanism occurs when alkyl tosylates are treated with strong nucleophiles and bases?
SN2
What happens to the configuration of the stereogenic center when the leaving group is bonded to it during substitution?
Inversion of configuration
What is the purpose of converting alcohols to tosylates?
To convert a poor leaving group to a good one
What reaction occurs when alkyl tosylates are treated with strong bases?
Both nucleophilic substitution and β elimination
What is required for ethers to undergo substitution or elimination reactions?
Conversion of poor leaving group into a good leaving group by reaction with strong acid
What type of mechanism is involved in the cleavage of the C-O bond when 2° or 3° alkyl groups are bonded to the ether oxygen?
SN1 mechanism
What is the result of the reaction between ethers and HBr or HI?
Two alkyl halides are formed as products
What is the characteristic of the three-membered ring in epoxides that makes nucleophilic attack favorable?
It is a strained ring
What is the necessary condition for nucleophilic addition to epoxides to occur?
The presence of a strong nucleophile
Why do epoxides not contain a good leaving group?
Because they contain a strained three-membered ring
What is the type of mechanism involved in the cleavage of the C-O bond when methyl or 1° R groups are bonded to the ether oxygen?
SN2 mechanism
What is the mechanism of attack by a nucleophile on an electron-deficient carbon in an epoxide ring?
SN2
What is the product of the protonation of the alkoxide in the second step of the epoxide ring opening reaction?
A neutral product with Mo functional groups
Which of the following is NOT a common nucleophile that opens an epoxide ring?
—NO2
What is the role of acid in the epoxide ring opening reaction with H2O or ROH?
To act as a catalyst
What is the characteristic of the epoxide ring opening reaction with either a strong nucleophile or an acid HZ?
Regioselective
What is the difference in site selectivity between the epoxide ring opening reactions with a strong nucleophile and an acid HZ?
They are opposite
What is the driving force behind the epoxide ring opening reaction?
Relief of steric strain
What is the role of HCI, HBr, and HI in the epoxide ring opening reaction?
Act as acids to open the epoxide ring
What is the product of the reaction of an epoxide with an acid HZ?
A neutral product with Mo functional groups
What is the role of the nucleophile in the first step of the epoxide ring opening reaction?
To attack an electron-deficient carbon
Which of the following is a common nucleophile that opens an epoxide ring?
—OH
What is the result of the protonation of the alkoxide in the second step of the epoxide ring opening reaction?
A neutral product with Mo functional groups on adjacent atoms
What is the characteristic of the epoxide ring opening reaction with either a strong nucleophile or an acid HZ?
It is a regioselective reaction
What is the difference between the site selectivity of the epoxide ring opening reactions with a strong nucleophile and an acid HZ?
The site selectivity is opposite for both reactions
Which of the following acids can open an epoxide ring?
HCI
What is the role of water in the epoxide ring opening reaction with an acid HZ?
To protonate the alkoxide
Why do strong nucleophiles open an epoxide ring?
Because the ring is strained
What is the mechanism of the first step of the epoxide ring opening reaction?
SN2
What is the driving force behind the relief of the strain of the three-membered ring?
The formation of a more stable product
The epoxide ring opening reaction with a strong nucleophile is a one-step reaction.
False
Acids such as HCl, HBr, and HI can open an epoxide ring.
True
The site selectivity of the epoxide ring opening reactions with a strong nucleophile and an acid HZ is the same.
False
NH3 is a common nucleophile that opens an epoxide ring.
True
The epoxide ring opening reaction is non-regioselective.
False
The three-membered ring in epoxides is strain-free.
False
Water is not involved in the epoxide ring opening reaction with an acid HZ.
False
The alkoxide is not protonated in the second step of the epoxide ring opening reaction.
False
The epoxide ring opening reaction with a strong nucleophile is a reversible reaction.
False
ROH can open an epoxide ring in the presence of acid.
True
Test your understanding of alcohols in organic chemistry, including their conversion to alkyl bromides and alkyl tosylates, and the role of tosylate as a leaving group. Learn about the mechanism and formation of tosylates and their uses in organic reactions.
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