Organic Chemistry I-2 Flashcards
Which of the following molecules has a net dipole moment of zero?
- CH4
- CO2
- BH3
- All of them
All of them
Here all the 3 molecules have symmetrical shapes and the central atoms are bonded with same atoms. So, the dipole moments cancel out each other resulting in no net dipole moment.
True or False: Constitutional isomers are different molecules having the same molecular formula.
True
Explanation: Constitutional isomers, also called structural isomers, have the same number and types of atoms (same molecular formula) but differ in how those atoms are connected within the molecule, leading to different structures.
True or False: Resonance structures have the same placement of atoms but different arrangement of electrons.
True
Resonance structures have the same placement of atoms but differ in the arrangement of electrons, specifically the distribution of electrons in bonds and lone pairs.
This allows for the depiction of molecules where the electron distribution cannot be represented by a single Lewis structure.
True or false: Electronegativity decreases across a row of the periodic table.
False
On the periodic table, electronegativity generally increases as you move from left to right across a period and decreases as you move down a group.
True or False: Covalent bonds result from the transfer of electrons from one element to another.
False
Explanation:
Covalent bond: When two atoms share electrons to achieve a stable electron configuration.
Ionic bond: When one atom completely transfers electrons to another, creating oppositely charged ions that attract each other.
Which of the following statements about electronegativity and the periodic table is true?
Electronegativity decreases across a row of the periodic table.
Electronegativity increases down a column of the periodic table.
Electronegativity increases across a row of the periodic table.
Electronegativity does not change down a column of the periodic table.
Electronegativity increases across a row of the periodic table.
Which of the following statements about valence electrons is true?
They are the most tightly held electrons.
They do not participate in chemical reactions.
They are the outermost electrons.
They reveal the period number of a second-row element.
They are the outermost electrons.
Explanation: Valence electrons are located in the outermost energy level of an atom. This makes them the most accessible to other atoms when forming chemical bonds. They are responsible for an atom’s reactivity and chemical behavior.
What is the molecular geometry around the boron atom in BH3?
Tetrahedral
Trigonal Planar
Trigonal Pyramidal
Linear
Trigonal Planar
Explanation: Boron has three valence electrons, which it uses to form single bonds with three hydrogen atoms, resulting in a symmetrical planar arrangement with bond angles of approximately 120 degrees.
Consider compounds which contain both a heteroatom and a double bond. For which compound is no additional Lewis structure possible?
Compound III
Which of the following is the appropriate conversion of (CH3)2CHCH2CHClCH3 to a skeletal structure?
(II)
Which of the following pair does not represent resonance structures?
III
What 2 things will change between two resonance structures?
The position of multiple bonds and non-bonded electrons.
Which of the following molecules has a net dipole moment of zero?
II the net dipole moment is zero.
What is the hybridization for each of the indicated atoms in the following compound?
I = sp2; II = sp2; III = sp3.
Explanation :
Hybridization (H) = Number of electrons domains around atom (i.e. No. of bond pairs + No.of lone pairs , including multiple bond as a single bond).
If H = 2 , then Hybridization = sp
If H = 3 , then Hybridization = sp2
If H = 4 , then Hybridization = sp3
Which of the following Lewis structures is correct?
Lewis’s structures II and III are correct.
Which of the following molecules has non-polar covalent bonds?
CO2
N2
CCl4
HF
N2
Which of the following Lewis structures is correct?
IV
Consider compounds which contain both a heteroatom and a double bond. For which compound is no additional Lewis structure possible?
III
What is the formal charge of the carbon in carbon dioxide (CO2) when drawn with two double bonds?
0
Which of the following molecules contain both covalent and ionic bonds?
II, IV
In conclusion, among the molecules listed, Ammonium hydroxide and Magnesium carbonate are the two compounds that contain both covalent and ionic bonds.
What is the molecular geometry around the carbon atom in CH4?
Tetrahedral
It results from the carbon atom’s sp3 hybridization, which allows the four hydrogen atoms to arrange themselves as far apart as possible, forming bond angles of approximately 109.5 degrees.
Follow the curved arrows to draw the second resonance structure for the ion below.
III
True or False: Lewis bases are electron pair acceptors.
False
Lewis bases are electron pair donors, not acceptors. Lewis acids are the electron pair acceptors.
Which of the following statements explain why HBr is a stronger acid than HF?
Br − is more stable than F − because Br − is larger than F −.
Br − is less stable than F − because Br − is larger than F −.
Br − is more stable than F − because Br − is less electronegative than F −.
Br − is less stable than F − because Br − is less electronegative than F −.
Br − is more stable than F − because Br − is larger than F −.
True or False: CBr4 is a Lewis acid
False
Which of the following is an acid commonly used it organic reactions?
HCI
NaOH
KOH
NaNH 2
HCl
True or False: All Brønsted-Lowry bases contain a lone pair of electrons or a π bond.
True
Which of the following statements about acid strength is true?
The stronger the acid, the further the equilibrium lies to the left.
The stronger the acid, the smaller the Ka.
The stronger the acid, the larger the pKa.
The stronger the acid, the smaller the pKa.
The stronger the acid, the smaller the pKa.
What is the nucleophilic site in the following compounds?
I = Oxygen; II = π electrons in bond; III = nitrogen.
Rank the following conjugate bases in order of decreasing basicity, putting the most basic first.
III > I > II
Which of the following compounds is the weakest acid?
HF
HCI
HBr
HI
HF
Order of acid strength: HF < HCl < HBr < HI.
Which of the following concepts can be used to explain the difference in acidity between ethanol (CH 3CH 2OH) and 2-fluoroethanol (FCH 2CH 2OH)?
Inductive effect
Consider the following structures I-IV. Which two species represent a conjugate acid-base pair?
I and II
Which is the conjugate acid in the following reaction?
III
Which of the following species is the weakest base?
HO –
H2N−
CH3COO−
Cl−
Cl−
Cl- is the conjugate base of a strong acid (HCl), making it very weak in its ability to accept a proton.
Which of the following statements about a Brønsted-Lowry base is true?
The net charge may be zero, positive, or negative.
All Brønsted-Lowry bases contain a lone pair of electrons or a π bond.
All Brønsted-Lowry bases contain a proton.
The net charge may be zero or positive.
All Brønsted-Lowry bases contain a lone pair of electrons or a π bond.
True or False: π bonds confer reactivity on a particular molecule because π bonds are easily broken in chemical reactions.
True
True or False: Ionic bonds allow for sharing of electrons.
False
Ionic bond involves a transfer of electrons whereas covalent bond involves sharing of electrons.
True or False: The relationship between the surface area of a molecule and the strength of the intermolecular forces states that the larger the surface area, the weaker the intermolecular forces.
False.
The larger the surface area of a molecule, the stronger the intermolecular forces.
True or False: There are 20 naturally occurring amino acids.
True
Explanation: While hundreds of amino acids exist in nature, only 20 are commonly found in proteins and considered “naturally occurring” in most living organisms.
True or False: Hydrogen bonding is the strongest intermolecular force within covalent bonds
True
Hydrogen bonding is considered the strongest intermolecular force among covalent bonds, as it is a special type of dipole-dipole interaction that occurs when a hydrogen atom is bonded to a highly electronegative atom like oxygen, nitrogen, or fluorine
List the intermolecular forces present in the following molecule:
Van der Waals
Dipole-dipole interactions
Hydrogen bonding
What molecular features are required for soap to properly dissolve grease and oil?
The molecule must contain both a polar head and a non-polar tail.
Which of the following is a secondary alcohol?
Structure IV: The OH group is attached to a carbon that is connected to two other carbon atoms. This is a secondary alcohol.
Which of the following correctly matches the molecules to the names of the functional group?
I. CH3OH Carboxylic acid
II. CH3CO2CH3 Ester
III. CH3COCH3 Ketone
IV. H2CO Alcohol
II and III
Which of the following lists the correct functional groups found in aspartame, the artificial sweetener?
Amine, amide, aromatic, carboxylic acid, ester
Consider the molecule donepezil (used to treat Alzheimer’s disease). Which of the following lists the correct functional groups present in donepezil?
Amine, aromatic, ester, ketone.
In donepezil there are four functional groups :
1). Tertiary amine (-N=)
2). Aromatic benzene ring
3). Ether (OCH3 groups attached with benzene ring)
4). ketone (C=O)
Which of the following compounds has the highest boiling point?
II
Which of the following molecules contain the same functional groups?
I, II, IV all are amines.
How many fatty acids are there in a triacylglycerol?
3
Triacylglycerol is composed of three fatty acids esterified to a glycerol molecule
Which of the following compounds would be expected to be more soluble in hexane (C6H14)?
The compound I will be more soluble in hexane.
True or False: Acyclic alkanes contain carbons joined in one or more rings.
False
True or False: Cyclic alkanes have two fewer H atoms than acyclic alkanes with the same number of carbons.
True
Cyclic alkanes are hydrocarbons that contain one or more rings of carbon atoms, whereas acyclic alkanes, also known as linear or straight-chain alkanes, are hydrocarbons that have a chain of carbon atoms with no rings.
True or False: Cyclohexane has the least angle strain
True
Angle strain refers to the increase in energy caused by deviation from the ideal bond angle in cycloalkanes.
Among common cycloalkanes, cyclohexane has the least angle strain because it can adopt a “chair” conformation that minimizes strain by allowing bond angles close to the ideal tetrahedral angle (109.5°)
True or False: A staggered conformation with two larger groups 60° from each other is called anti.
False
In a staggered conformation, when two larger groups are 60 degrees from each other, it is called a gauche conformation.
An anti-conformation occurs when the two larger groups are 180 degrees from each other.
True or False: Rotating the atoms on one carbon by 60° converts an eclipsed conformation into a staggered conformation, and vice versa.
True
Explanation:
Staggered conformation:
In a staggered conformation, the substituents on adjacent carbons are as far apart as possible, with a dihedral angle of 60 degrees.
Eclipsed conformation:
In an eclipsed conformation, the substituents on adjacent carbons are directly aligned with each other, resulting in a dihedral angle of 0 degrees.
Key point: Rotating one carbon by 60 degrees along the carbon-carbon bond is the necessary movement to switch between these two conformations.
What is the IUPAC name for the following compound?
1- sec-Butyl-3-methylcyclohexane
Which of the following chair conformations represents trans-1,3-dimethylcyclohexane?
IV
What is the relation between the following pair of compounds?
Stereoisomers
Compounds (I) and (II) have the same molecular formula and connectivity of atoms, but different spatial arrangement of one of the methyl groups in space, therefore, they are stereoisomers. They are cis and trans isomers.
Which of the following is not another representation for 2-methylbutane?
IV
Which of the following are anti conformers of butane?
II and IV
What are the products of the combustion of alkanes?
carbon dioxide and water
Explanation: Alkanes react with oxygen during combustion, breaking down their carbon-hydrogen bonds to form carbon dioxide and water molecules, releasing heat energy in the process.
Which of the following statements about alkanes is not true?
Alkanes are aliphatic hydrocarbons.
Alkanes contain only C-C and C-H s bonds.
Alkanes are acyclic or cyclic.
Acyclic alkanes have two fewer H atoms than cyclic alkanes with the same number of carbons.
Acyclic alkanes have two fewer H atoms than cyclic alkanes with the same number of carbons.
Which of the following compounds has only primary and secondary hydrogen atoms?
2-Methylpentane
2,2,3-Trimethylpentane
3-Methylpentane
2,2-Dimethylpentane
2,2-Dimethylpentane
Which of the following represents the oxidation of an organic compound?
Adding nitrogen to the molecule
Adding chlorine to the molecule
Adding oxygen to the molecule
All of these are correct
Adding oxygen to the molecule
a process where a carbon atom within a molecule gains bonds to more electronegative atoms, typically oxygen, resulting in a loss of hydrogen bonds and an increase in the molecule’s oxidation state
essentially, the carbon atom becomes more oxidized by losing electrons to the newly formed bond with oxygen.
True or False: A pair of diastereomers are mirror images of each other
This statement is false. A pair of diastereomers are not mirror images of each other; they are stereoisomers that have different configurations at one or more stereocenters but are not mirror images.
True or False: Stereoisomers differ only in their structural formula.
False
Stereoisomers have the same structural formula but differ in their spatial arrangement of atoms in three-dimensional space
True or False: A meso compound is chiral.
False
A meso compound is an achiral compound that has chiral centers.
True or False: Enantiomers are mirror images that are not superimposable.
True
Enantiomers are stereoisomers that are non-superimposable mirror images.
True or False: A chiral molecule usually contains a plane of symmetry.
False
A chiral molecule does not contain a plane of symmetry; a key characteristic of a chiral molecule is that it lacks a plane of symmetry, meaning it cannot be divided into two mirror-image halves
True or False: A catalyst accelerates a reaction by lowering the energy of activation.
True
A catalyst in a reaction decreases the activation energy, not the energy gap between the reactants and products. T
True or False: Carbocations are electrophiles.
True
All carbocations are electrophiles. All carbanions are nucleophiles.
True or False: A rate equation contains concentration terms for all reactants involved in a one-step mechanism.
True
Larger rate constants imply faster reactions, and rate equations typically reflect the rate-determining step in multi-step mechanisms.
True or False: Equilibrium favors the products when they are less stable than the starting material of a reaction.
False
What is the relationship between the following two compounds?
Constitutional isomers
Which of the following compounds has a plane of symmetry?
III and IV
Give the IUPAC name for the following compound:
(3S,4R)-4-chloro-3-hexanol
Which of the following cyclic molecules is a meso compound?
II
What is the relationship between the following compounds?
The compounds are identical.
Which of the following structures has the R configuration?
Only I and II
How many isomers can be drawn (constitutional and stereoisomers. for dimethycyclopropane?
4
How many stereogenic centers are present in the following compound?
1
Which of the following is the definition of chirality?
The existence of a molecule that is not superimposable on its mirror image.
How many stereogenic centers are present in ephedrine, a bronchodilator and decongestant?
2
True or False: SN2 mechanism for nucleophilic substitution reactions involves one step and occurs with inversion of configuration.
True
True or False: The characteristic reactions of alkyl halides are elimination and substitution.
True
True or False: SN1 reaction involves two steps and occurs fastest with tertiary alkyl halides.
True
True or False: The conjugate bases of strong acids are good leaving groups.
True
True or False: In polar protic solvents, nucleophilicity decreases down a column of the periodic table as the size of the anion increases.
False
Which compound would you predict to be highest in energy?
Structure B is The Most Unstable
Structure B, a carbon atom with a positive charge, is higher in energy because it is electron-deficient and lacks a stable tetravalent electron configuration, which a neutral carbon atom typically has.
The symbol Δ stands for ________ in a chemical reaction.
the symbol Δ stands for heat being applied to the reaction
it indicates that the reaction requires heat to proceed
Which of the following letters represents DH° for the forward reaction in the following energy diagram?
D
A = Energy of the reactant
B = activation energy of the forward reaction that is energy require to convert reactant to product
C = activation energy of the backward reaction that is energy require to convert reactant to product to reactant
D = energy of the product and
enthalpy of the reaction
Which of the following statements about substitution reactions is true?
Substitution reactions involve π bonds.
Substitution reactions involve σ bonds.
One σ bond breaks and another forms at a different carbon atom.
One π bond breaks and another forms at the same carbon atom.
Substitution reactions involve σ bonds
In a Substitution reaction, one sigma bond is broken and another is usually added to the same Carbon atom.
What type of reaction does the following conversion represent?
The given reaction is an elimination reaction.
Using the bond dissociation energies given, calculate DH° for the following reaction.
−3 KJ/mol
How many steps are there in a concerted mechanism?
1
What is the name given to the reaction species that lies at an energy minimum between steps on a reaction energy diagram?
Reactive intermediate
Option A refers to the transition state, which is actually a high-energy configuration of the reactant molecules (not an energy minimum) that exists at the peak of the energy barrier during a reaction.
Option B refers to the activation energy, which is the energy required to reach the transition state from the reactant molecules.
Option D refers to an equilibrium product, which is the product of a reaction that is in equilibrium with the reactants.
A reaction that results in the formation of a carbocation is most likely to occur from the following:
Heterolytic bond cleavage
What type of bond cleavage takes place in/what type of intermediate is produced in the following reaction?
the type of bond cleavage is heterolytic cleavage, or heterolysis, and the reaction’s intermediate is a carbocation
Concept:
A positively charged carbon compound is a carbocation
A negatively charged carbon compound is a carbanion
For the following reaction, use the identity of the alkyl halide and nucleophile to determine which substitution mechanism occurs. Then determine which solvent affords the faster reaction.
The given reaction will proceed through Sn2 mechanism and the solvent at which the rate of the given DMF reaction would be faster is
What is the product of the nucleophilic substitution reaction shown below?
I and II
Which of the following alkyl halides is a primary alkyl halide?
I
The reaction of 1-bromobutane with sodium hydroxide affords the substitution product 1-butanol. What would happen to the rate of the reaction if the concentration of both 1-bromobutane and sodium hydroxide were doubled?
The rate increases by a factor of 4.
Which of the following anions is the most nucleophilic in polar aprotic solvents?
F −
Cl −
Br −
I −
F −
Which of the following statements about the reactions of alkyl halides is true?
The characteristic reactions of alkyl halides are addition and elimination.
The characteristic reactions of alkyl halides are addition and substitution.
The characteristic reactions of alkyl halides are elimination and substitution.
The characteristic reactions of alkyl halides are oxidation and reduction.
The characteristic reactions of alkyl halides are elimination and substitution.
Rank the following compounds in order of decreasing SN1 reactivity?
III > II > I > IV
The order of alkyl halides in SN1 is tertiary > secondary > primary > vinylic.
What is the IUPAC name of the following compound?
2-Chloro-4-methylpentane
According to the rule,
a) The main chain has five carbon atoms (pent). it belongs to the alkane group
b) Numbering the parent chain,
The structure is an alkane group. Therefore, the numbering should start from the end nearest to the substituent and aim to assign the lowest possible number to the substituent.
c) Due to the alkane group, the prefix will be used “ ane”
After numbering, we can see that the chlorine atom is present at the second carbon, and the methyl group is present as a substituent at the fourth carbon.
Given the following substitution reaction, what would be the effect of changing the solvent from CH3OH to (CH3)2S=O? CH3(CH2)5Br + NaOH → CH3(CH2)5OH + Br−
The rate would increase because polar aprotic solvents favor SN2 reactions
Which of the following statements about carbocation stability is true?
Carbocations are stabilized by electron-withdrawing inductive effects only.
Carbocations are stabilized by electron-withdrawing inductive effects and hyperconjugation.
Carbocations are stabilized by electron-donating inductive effects only.
Carbocations are stabilized by electro-donating inductive effects and hyperconjugation.
Carbocations are stabilized by electro-donating inductive effects and hyperconjugation.
True or False: An E1 mechanism will identify the leaving group as it affects the rate of reaction.
True
An E1 mechanism has stronger bases that favor the E1 reaction.
False
E1 reaction is favored by weakly basic or acidic conditions.so a strong base can’t favor it.
True or False: The mechanism of an E2 reaction will exhibit first-order kinetics.
False
It exhibits second-order kinetics :)
True or False: The E1 mechanism has the loss of a proton by the carbocation as the slow step.
False
True or False: Entropy favors the formation of the product of an E2 reaction.
True
What is the major elimination product obtained from the following reaction?
I
How many unique β carbons are found in the alkyl halide below?
2 unique β-carbons
Which of the following is the dihalide that can be used to prepare the alkyne below?
I, II, and III
What is the most likely mechanism for the reaction below?
SN2
Which of the following alkyl halide reacts the fastest in an E2 reaction?
The alkyl halide which will react at a faster rate in E2 mechanisms among the provided options is (II).
What is the major elimination product obtained from the following reaction?
III
Which of the following is the least reactive substrate in an E2 reaction?
I
E2 elimination is done by elimination of beta-hydrogen.
Which alkyl halide(s) would give the following alkene as the only product in an elimination reaction?
Only II
What is the product of the following reaction?
II
Which of the following is the major elimination product of the following reaction?
IV
True or False: Zileuton has been shown to treat the cause of asthma.
True
Patients with mild-to-moderate chronic asthma use zileuton to decrease the symptoms of asthma and the number of acute asthma attacks.
Zileuton prevents wheezing, shortness of breath, coughing, and chest tightness due to asthma.
True or False: Sodium phenoxide and bromomethane provide the best yield of ether by the Williamson ether synthesis.
True
True or False: The crown ether-cation complex is thought of as the crown ether as the guest and the cation as the host.
False
In a crown ether-cation complex, the crown ether acts as the host because it provides the cavity that encapsulates the guest cation through coordination interactions.
True or False: The reaction of ethers with strong acids yields the mechanism of ether cleavage by SN1 and SN2.
True
The reaction of ethers with strong acids leads to ether cleavage through either the SN1 or SN2 mechanism, depending on the structure of the ether and the reaction conditions.
True or False: The migrating group in a 1,2-shift moves with one bonding electron.
False
In a 1,2-shift, the migrating group moves with both bonding electrons, forming a new bond with the adjacent positively charged atom (usually a carbocation).
What is the product, if this reaction occurs via an SN2 mechanism?
II
Which of the following explains why epoxides are much more reactive than ethers?
The C-O-C bond angle of an epoxide is 109°, making epoxides to have angle strain.
The oxygen atom of an epoxide is sp2 hybridized.
The C-O-C bond angle of an epoxide is 120°, making epoxides to have angle strain.
The C-O-C bond angle of an epoxide is 60°, making epoxides to have angle strain.
The C-O-C bond angle of an epoxide is 60°, making epoxides to have angle strain.
What is the best choice of reagent to accomplish the following transformation?
H2SO4
Rank the following compounds in order of increasing boiling point, putting the compound with the lowest boiling point first.
III < II < I < IV
What is the IUPAC of the following compound?
4-Ethoxyoctane
What is the best choice of reagent to accomplish the following transformation?
POCl 3, pyridine
What is the major alkene formed when compound A is dehydrated with POCl3 and pyridine?
I
Which of the following compounds is (are. primary alcohols?
The primary alcohol is = II
Which of the following ethers cannot be prepared by the Williamson ether synthesis?
Isopropyl methyl ether
tert-Butyl methyl ether
tert-Butyl phenyl ether
Methyl phenyl ether
tert-Butyl phenyl ether
What are the major products obtained upon treatment of ethyl methyl ether with excess HBr?
Bromomethane and ethanol
Bromoethane and methanol
Bromoethane and bromomethane
Ethanol and methanol
Bromoethane and methanol
True or False: The stereochemistry of electrophilic addition of HX to alkenes allows hydrohalogenation to occur with syn and anti addition of HX.
True.
The electrophilic addition of HX to alkenes follows Markovnikov’s rule, where the hydrogen adds to the carbon with more hydrogen substituents, and the halide adds to the more substituted carbon.
True or False: Alkenes are less reactive than alkanes.
False.
Alkenes are more reactive than alkanes due to the presence of a pi bond, which is weaker and more reactive than the sigma bonds in alkanes.
The pi bond in alkenes can participate in electrophilic addition reactions, making them more chemically reactive compared to the relatively stable single bonds in alkanes.
True or False: The electrons in the pi bonds of alkynes are more tightly held than those of alkenes.
True.
In alkynes, the carbon-carbon triple bond consists of one sigma bond and two pi bonds.
True or False: The hydroboration/oxidation of alkenes enables the oxidation with retention of configuration.
True.
In the hydroboration-oxidation reaction of alkenes, boron adds to the less substituted carbon (anti-Markovnikov addition) in a syn addition with hydrogen.
True or False: The properties of the carbon-carbon double bond is whenever the two groups on each end of a carbon-carbon double bond are the same, two diastereomers are possible.
False.
For diastereomers to exist, there must be at least two stereocenters or a form of geometric isomerism (cis/trans or E/Z) where different groups are present on each carbon of the double bond.
