Organic Chemistry ACS Final II
Terms in this set (37)
Any alkene with at least one halide substituent bonded directly on one of the alkene carbons
T/F Vinylic halides may undergo SN2 reactions
False, they do not
A molecule may undergo reaction slower if...
there is steric hindrance...such as being a secondary as opposed to a primary halide
A substituent with the structural formula H2C=CH-CH2R, where R is the rest of the molecule. It consists of a methylene bridge (-CH2-) attached to a vinyl group (-CH=CH2).
undergo SN2 reactions faster than the corresponding simple alkyl halides
T/F Aryl halides and phenols do not undergo Sn2 or Sn1 reactions
Cleavage of an ether usually requires
A strong acid that has a conjugate base which is a strong nucleophile (i.e. HBr, HI)
When an ether is cleaved, depending on the type of alkyl group, the acid reaction w/ the halide ion produces
an alkyl halide
under the usual reaction conditions, when an ether is cleaved, an excess of the halogen acid is used which converts the initial alcohol into a
secondary aryl halide
The only type of ethers that are not cleaved by HBr or HI
Ring opening reactions of epoxides occurs by
The regiochemistry of the opening of an epoxide by nucleophilic attack depends on
if the oxygen atom is protonated prior to the attack
When the oxygen of the epoxide is not protonated before nucleophilic attack, the nucleophile
behaves in Sn2 fashion, attacking at the less substituted carbon atom
when the oxygen atom of the epoxide is protonated before nucleophilic attack, the nucleophile
attacks the more highly substituted carbon atom if it is a tertiary carbon atom, otherwise, it occurs at both spots giving a mixture of products
in ring opening, the nucleophile must attack from
the backside of the carbon oxygen bond (Sn2) retaining the configuration at the site that becomes the alcohol
Fused ring epoxides will give a product in which the nucleophile and the OH group are ________ to each other
T/F Vinylic cations are more stable than alkyl cations
secondary and tertiary alcohols react with the hydrogen halides via ____ mechanism
The majority of E2 eliminations require a transition state conformation in which the beta-hydrogen atom and leaving group are arranged ______ .
When elimination occurs in a cyclohexane ring, the fact that they must be anti means the hydrogen atom and the leaving group must be _______ and ________.
trans and diaxial
Factors affecting the regiochemistry of beta-eliminations
-the base preferentially abstracts the least sterically hindered beta-hydrogen atom
When potassium hydroxide is the base, the product accounts for 45% of the mixture, when postassium tert-butoxide is the base, the product accounts for 70%, what is to be expected if potassium propoxide were the base?
An organic reaction in which alkyl halide when boiled with alcoholic alkali gives corresponding alkene. It is also called a β-Elimination reaction. An alkene is formed due to formation of a double bond between the α- and β-carbon
An empirical rule for predicting the favored alkene product(s) in elimination reactions
Zaitsev's rule (or Saytseff's rule)
In elimination reactions, "The alkene formed in greatest amount is the one that corresponds to removal of the hydrogen from the β-carbon having the _______ hydrogen substituents."
When we dehydrohalogenate a cis product we end up with how many structures?
When we dehydrohalogenate a trans product we end up with how many structures?
Why would concentrated hydrobromic acid be an inappropriate catalyst for the dehydration of alcohols?
The conjugate base, Br-, is a good nucleophile and would attack the carbocation to form an alkyl bromide
Place in order of stability regarding carbocations...primary, secondary, tertiary.
tertiary > secondary > primary
because of carbocation stability, a tertiary alcohol will be more/less stable than a primary
In a prototypical nucleophilic substitution reaction, the effect of doubling the volume of solvent would be to multiply the reaction rate by a factor of
What would be the first step in the dehydration of cyclohexanol in sulfuric acid?
protonation of the alcohol
a one-step process with inversion of the configuration
in Sn2 reactions arrange from fastest to slowest...primary halide, secondary halide, tertiary halide
primary > secondary > tertiary
When looking at nucleophiles, one of the weakest is
ester (carboxyl group)
A special type of nucleophilic substitution (SN1) or elimination where the nucleophile is a solvent molecule
Markovnikov's rule says the hydrogen atom is added to the carbon with the _______ number of hydrogen atoms while the X component is added to the carbon with the _____ number of hydrogen atoms.
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