Practice MCQ For Govt Pharmacist Exam, in this article we will solve, Practice MCQ on the topic, Stability of conjugated dienes under the subject Pharmaceutical organic chemistry of second semester. Read following article for your reference.
Stability Of Conjugated Dienes » PHARMACAREERS
Which of the following statements regarding alkadienes is incorrect?
a) These are acyclic acids
b) These are unsaturated hydrocarbons
c) These compounds have only one C=C bond
d) These compounds have the general formula CₙH₂ₙ₋₂
How many types of alkadienes are there?
a) 1
b) 2
c) 3
d) 4
Which of the following statements regarding conjugated double bonds in alkadienes is incorrect?
a) 1,3 alkadienes have conjugated double bonds
b) Compounds with a double bond exhibit this type of bond
c) 1,3 pentadiene is an example of this bond
d) The conjugated dienes have properties similar to that of alkenes
Which of the following is a perfect example of an isolated double bond?
a) 1,4 pentadiene
b) 1,2 pentadiene
c) 1,3 pentadiene
d) 1,5 butadiene
True or False: Dienes show cis-trans isomerism.
a) True
b) False
Conjugated dienes react with which of the following to form a cyclohexene?
a) Phenol
b) Dienophile
c) Hexane
d) Tribromo phenol
Which type of dienes undergo addition with the help of radical-chain mechanism?
a) Cumulated dienes
b) Isolated dienes
c) Simple dienes
d) Conjugated dienes
Which statement is related to the Diels-Alder reaction?
a) It is very stereospecific
b) Molecular distortion takes place
c) Cyclic dienes react slower than linear chain dienes
d) Addition of maleic anhydride to cyclopentadiene causes diene and dienophile to produce different products
A molecule in which more than one single bond separates two double bonds is called as:
a) Coordinate bond
b) Isolated double bond
c) Cumulative double bond
d) Conjugated double bond
Isolated dienes are similar in property to:
a) Monoolefins
b) Diolefins
c) Triolefins
d) Tetraolefins
What is the mechanism for the Diels-Alder reaction?
a) Electrophilic aromatic substitution
b) Oxidation mechanism
c) Nucleophilic addition
d) A concerted reaction involving a 6-member cyclic transition state
What is the dienophile in the Diels-Alder reaction?
a) N-methylmaleimide
b) Furan
c) Anthracene-9-methanol
d) Maleimide
What is the dienophile in the Diels-Alder reaction?
a) N-methylmaleimide
b) Furan
c) Anthracene-9-methanol
d) Maleimide
The reaction is ____ in water than in many common organic solvents:
a) Slower
b) Faster
The hydroxyl methyl group in anthracene-9-methanol _____ its reactivity:
a) Reduces
b) Increases
The carbonyl groups in N-methylmaleimide ______ their reactivity:
a) Reduce
b) Increase
Name two positive aspects for the reaction that meets the green chemistry principle:
a) High atom economy and water as the solvent
b) Low atom economy and organic solvents
c) High atom economy and organic solvents
d) Low atom economy and water as the solvent
In the Diels-Alder reaction, the molar ratio of anthracene-9-methanol/N-methylmaleimide is 1/2. How was the excess of N-methylmaleimide removed from the product during purification?
a) Filtration
b) Water washes
c) Vacuum distillation
d) Crystallization
What is the mechanism for the Diels-Alder reaction?
a) Electrophilic aromatic substitution
b) Oxidation mechanism
c) Nucleophilic addition
d) A concerted reaction involving a 6-member cyclic transition state
Which type of addition product is almost always formed when conjugated dienes undergo radical-chain mechanisms?
a) 1,2-adduct
b) 1,4-adduct
c) 1,3-adduct
d) 1,6-adduct
What is the primary reason that conjugated dienes undergo radical additions more readily than most alkenes
a) They have isolated double bonds.
b) They lack resonance stabilization.
c) They have fewer π electrons.
d) They have no isolated double bonds.
Which of the following statements about the reaction of hydrogen chloride with 1,3-butadiene is correct?
a) A carbocation is formed at C2.
b) The charge is distributed over two carbons when a proton is added to C1.
c) The 1,2-addition product is favored.
d) The reaction occurs via a concerted mechanism.
In reactions where both 1,2 and 1,4 additions occur simultaneously, the product ratio depends on which factors?
a) Temperature, solvent, and reaction time
b) Catalyst, pressure, and concentration
c) pH, temperature, and light exposure
d) Solvent, pH, and catalyst
Which type of rearrangement involves a carbon atom moving between an allyl double bond and the next carbon atom in an organic compound?
a) Electrophilic rearrangement
b) Nucleophilic substitution
c) Allylic rearrangement
d) Radical rearrangement
What is the major product formed when hydrogen bromide radicals add to 1,3-butadiene?
a) l-Bromo-1-butene
b) l-Bromo-2-butene
c) l-Bromo-3-butene
d) l-Bromo-4-butene
Which type of substitution involves a nucleophile attacking directly at the allylic position and displacing the leaving group in a single step?
a) SN1 substitution
b) SN2 substitution
c) E1 elimination
d) E2 elimination
What is the major reason that allylic carbocations are more stable than non-allylic carbocations?
a) Hyperconjugation
b) Inductive effect
c) Resonance
d) Steric hindrance
Which of the following statements about allylic rearrangement is correct?
a) It involves migration of a hydrogen atom.
b) It occurs via a concerted mechanism.
c) It leads to the formation of a new double bond.
d) It is specific to isolated dienes.
In allylic rearrangement, which carbon atom moves between an allyl double bond and the next carbon atom in the organic compound?
a) Carbon #1
b) Carbon #2
c) Carbon #3
d) Carbon #4
What type of rearrangement occurs when a nucleophile attacks directly at the allylic position and displaces the leaving group in a single step?
a) Electrophilic rearrangement
b) Nucleophilic substitution
c) Allylic rearrangement
d) Radical rearrangement
Which term refers to the product or products formed when one mole of reagent adds to one mole of substrate?
a) Monoadduct
b) Diadduct
c) Triadduct
d) Tetraadduct
When 1,3-butadiene reacts with an electrophile, which type of carbocation intermediate is possible?
a) Primary nonallylic carbocation
b) Secondary nonallylic carbocation
c) Primary allylic carbocation
d) Secondary allylic carbocation
In 1,2- and 1,4-additions to conjugated dienes, what do the numbers 1,2 and 1,4 actually indicate?
a) Positions of carbon atoms in the diene molecule
b) Number of double bonds in the diene
c) Neighboring carbon atoms
d) Separation of carbon atoms in the carbon chain
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