34 Questions
What stabilizes a molecule by delocalizing charge and electron density?
Resonance
How do halogens stabilize an adjacent positive charge?
By resonance
What is the product when one mole of X2 (X = Cl or Br) adds to an alkyne?
Dihalide
What happens when alkynes undergo hydration with concentrated acid?
They form ketones
What is the main reason why equilibrium favors the keto form in tautomers?
Stronger C=O bond
Which tautomer has a C=O and an additional C−H bond?
Keto
What is the purpose of the Hydroboration-Oxidation reaction sequence?
To convert an alkyne to a carbonyl compound
In Hydroboration-Oxidation, why does the hydroboration of a terminal alkyne result in an aldehyde?
Because BH2 adds to the less substituted, terminal carbon
Which catalyst is used for the reduction of alkynes to alkanes?
Palladium on calcium carbonate (Pd/C)
What happens when hydrogenation of alkynes is conducted with the Lindlar catalyst?
Reduction to an alkene with syn stereochemistry
Which type of addition occurs in hydroboration−oxidation of a terminal alkyne?
AntiMarkovnikov addition
Why does the terminally located borane in hydroboration−oxidation add to the terminal carbon of an alkyne?
Due to lower steric hindrance at the internal position
What is the main product formed when disubstituted alkynes react with potassium permanganate in mild conditions?
Vicinal diketones
In the reaction of acetylide anions with alkyl halides, which type of alkyl halide yields the product of nucleophilic substitution the fastest?
1° alkyl halides
What is the mechanism involved when acetylide anions react with unhindered alkyl halides to yield products of nucleophilic substitution?
SN2
Steric hindrance around the leaving group causes which type of alkyl halides to preferentially undergo elimination by an E2 mechanism?
2° and 3° alkyl halides
What type of reaction forms new carbon-carbon bonds in high yield only with unhindered CH3X and 1° alkyl halides when reacting with acetylide anions?
Nucleophilic substitution
Ozonolysis of alkynes is used mainly for which purpose?
To find the location of the triple bond in an unknown compound
What is the primary purpose of retrosynthetic analysis in organic chemistry?
To work backwards from a target compound to determine the starting materials
In retrosynthetic analysis, what does an open arrow (⇒) indicate?
The product on the left and the starting material on the right
Which type of reactions are often categorized in retrosynthetic analysis?
Reactions forming new carbon-carbon bonds
How is a carbonyl group typically formed in a retrosynthetic analysis?
By hydration of a triple bond
What is the source of the acetylide anion used to form new C-C bonds in retrosynthetic analysis?
Acetylene treated with base
In retrosynthetic analysis, what role does functional group interconversion play?
Converting one functional group into another
During retrosynthetic analysis, we work forwards from a desired product to determine the starting materials.
False
In retrosynthetic analysis, the product is drawn on the left and the starting material on the right using an open arrow (⇒).
True
Functional group interconversions play a crucial role in designing a synthesis process.
True
Acetylene is used to prepare the acetylide anion by treatment with an acid.
False
Retrosynthetic analysis often categorizes reactions into those that form new carbon-oxygen bonds and those that convert one functional group into another.
False
Hydration of a triple bond leads to the formation of an alcohol group.
False
Steric hindrance around the leaving group causes primary alkyl halides to preferentially undergo elimination by an E1 mechanism.
False
Retrosynthetic analysis focuses on working backwards from a target compound to determine the starting materials.
True
In retrosynthetic analysis, acetylide anions are used to form new carbon-nitrogen bonds.
False
The synthesis process involves working from a desired product to identify potential intermediates.
False
Learn about the role of halogens in stabilizing carbocations through resonance in alkynes. Discover how halogens facilitate the addition reactions to alkynes and form dihalides and tetrahalides. Dive into the chemistry of halogenation of alkynes.
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