chapter 3 personal material Flashcards
everything on janice 1-8
What are the characteristic features of organic compounds?
A: Organic compounds commonly have C-C and C-H sigma (σ) bonds, which are strong, nonpolar, and not readily broken.
What additional structural features can organic molecules have?
A: Organic molecules may contain heteroatoms (atoms other than carbon or hydrogen) and π bonds (found in C=C and C=O double bonds).
What is a functional group?
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A: A functional group is an atom or a group of atoms with characteristic chemical and physical properties that determine the molecule’s reactivity
Why do heteroatoms confer reactivity on organic molecules?
A: Heteroatoms have lone pairs and create electron-deficient sites on carbon, making the molecule reactive.
Why do π bonds confer reactivity on organic molecules?
π Bonds are easily broken in chemical reactions, making the molecule a base and a nucleophile.
What is the role of the C-C and C-H sigma (σ) bonds in organic molecules?
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A: These bonds form the carbon backbone or skeleton to which functional groups are attached
How does a functional group behave regardless of the carbon skeleton size?
A: A functional group usually behaves the same, whether bonded to a small (e.g., two carbons) or large (e.g., 20 carbons) skeleton.
How is the carbon and hydrogen portion of an organic molecule often represented?
A: It is abbreviated by the capital letter “R,” with “R” bonded to a specific functional group.
Why is ethane considered unreactive?
Ethane has only C-C and C-H σ bonds, no polar bonds, lone pairs, or π bonds, resulting in no reactive sites.
What makes ethanol more reactive compared to ethane?
Ethanol has a hydroxy (OH) functional group, lone pairs, and polar bonds, making it reactive with various reagents.
What common heteroatoms are found in organic molecules?
Nitrogen, oxygen, sulfur, phosphorus, and halogens.
How does a π bond contribute to nucleophilicity?
A: The electron density in a π bond can interact with electrophiles, acting as a nucleophile in chemical reactions.
How does the hydroxy group affect the properties of ethanol compared to ethane?
A: The hydroxy group makes ethanol have polar C–O and O–H bonds, along with two lone pairs, making it more reactive than ethane, which has only nonpolar C–C and C–H σ bonds.
What are the structural differences between ethane and ethanol?
A: Ethane has only C–C and C–H bonds with no functional group, while ethanol has a hydroxy (OH) functional group, making it a simple alcohol.
Hydrocarbons.
Compounds containing a C–Z σ bond (Z = electronegative element).
Compounds containing a C=O group.
Into what three types can functional groups be subdivided?
Alkanes: Contain only C–C σ bonds and no functional groups (e.g., ethane, CH₃CH₃).
Alkenes: Contain a C=C double bond as a functional group (e.g., ethylene, CH₂=CH₂).
Alkynes: Contain a C≡C triple bond as a functional group (e.g., acetylene, HC≡CH).
What are the three subgroups of aliphatic hydrocarbons?
What distinguishes aromatic hydrocarbons from aliphatic hydrocarbons?
A: Aromatic hydrocarbons, such as benzene, contain a six-membered ring with three π bonds, which form a single functional group. Many have strong, characteristic odors.
What is the molecular formula of benzene, and what functional group does it form?
A: The molecular formula of benzene is C₆H₆, and it forms a single functional group with its six-membered ring and three π bonds.
What is a phenyl group?
A: A phenyl group is a benzene ring bonded to another group. For example, in phenylcyclohexane, a phenyl group is bonded to a cyclohexane ring.
What is the role of benzene in the BTX mixture?
A: Benzene, as a component of the BTX mixture, is added to gasoline to boost octane ratings.
What role do lone pairs on oxygen play in determining the reactivity of a molecule?
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A: Lone pairs on oxygen create electron density, making oxygen both a base and a nucleophile
How does the electron deficiency of carbon influence its reactivity in a C=O bond?
A: The electron-deficient carbon in a C=O bond acts as an electrophile, making it susceptible to nucleophilic attack.
Why is a π bond more reactive than a σ bond in organic molecules?
A: A π bond is weaker and easier to break than a σ bond, making it more reactive in chemical reactions.
What makes the C=O bond polar?
The difference in electronegativity between carbon (δ⁺) and oxygen (δ⁻) creates a polar bond.
Why is the oxygen atom in a C=O bond considered a Lewis base?
A: The oxygen atom has lone pairs of electrons, which can be donated to an electrophile.
Why is the carbon atom in a C=O bond considered a Lewis acid?
A: The carbon atom is electron-deficient and can accept electron pairs from nucleophiles.
How does a π bond make a molecule both a base and a nucleophile?
A: The π bond contains electron density that can be donated, allowing the molecule to act as a nucleophile or a base.
How do lone pairs and π bonds differ in their contribution to a molecule’s nucleophilicity?
A: Lone pairs are localized and directly available for donation, while π bonds provide delocalized electron density.
How does the presence of a carbonyl group (C=O) influence the properties of an organic molecule?
A: The carbonyl group introduces polarity, making the molecule reactive in nucleophilic addition or substitution reactions.
Why are π bonds considered a functional group?
A: π Bonds are regions of high electron density that significantly influence a molecule’s chemical reactivity.
How does the presence of lone pairs in functional groups affect molecular reactivity?
A: Lone pairs provide sites for nucleophilic attack and base interactions, increasing reactivity.
What functional group is represented by the C=O structure in the diagram, and what are its chemical properties?
A: The C=O structure represents a carbonyl group, which is polar and reactive with nucleophiles.
Why is the oxygen atom in the hydroxy group of ethanol considered a Lewis base?
A: The oxygen atom has lone pairs of electrons, which can be donated in chemical reactions.
How does the hydroxy group in ethanol make it a better hydrogen bond donor and acceptor?
A: The O–H bond can donate a hydrogen bond, while the lone pairs on oxygen can accept a hydrogen bond.
What makes the carbon atom in ethanol’s hydroxy group less electron-deficient than the oxygen atom?
A: Oxygen is more electronegative than carbon, pulling electron density toward itself and reducing the electron deficiency on carbon.
How does the presence of a hydroxy group affect the intermolecular interactions of ethanol compared to ethane?
A: The hydroxy group enables hydrogen bonding in ethanol, leading to higher boiling points and greater solubility in water compared to ethane.
Why is benzene considered a stable molecule despite having alternating double bonds?
A: Benzene is stabilized by delocalized π electrons across the ring, making it more stable than a molecule with isolated double bonds.
What type of hybridization is present in the carbon atoms of benzene?
A: The carbon atoms in benzene are
𝑠𝑝2 hybridized, forming a planar hexagonal structure.
How does the phenyl group differ from benzene in terms of structure?
The phenyl group is a benzene ring attached to another group, represented as
𝐶6𝐻5−, while benzene is a standalone molecule.
Why is the phenyl group considered an electron-donating group in some chemical reactions?
The delocalized π electrons in the benzene ring can donate electron density to adjacent atoms or functional groups.
How does the delocalized π system of benzene affect its behavior in electrophilic substitution reactions?
A: The delocalized π system makes benzene electron-rich and reactive toward electrophiles, favoring substitution rather than addition reactions.
How does the phenyl group influence the physical and chemical properties of phenylcyclohexane?
A: The phenyl group adds aromatic character, increases hydrophobicity, and influences reactivity by providing resonance stabilization.
How does the presence of a phenyl group affect the reactivity of a molecule in organic reactions?
A: The phenyl group can stabilize intermediates via resonance, making the molecule more reactive in electrophilic substitution and less reactive in addition reactions.
Polyethylene:
A stable alkane polymer consisting of long chains of -𝐶𝐻2- units.
Not reactive and resists degradation, persisting in landfills for years.
- What reaction occurs when ethanol (CH₃CH₂OH) is treated with:
• (a) H₂SO₄ (sulfuric acid)?
• (b) NaH (sodium hydride)?- What happens when ethane (CH₃CH₃) is treated with these same reagents?
Compounds with C–Z σ Bonds:
These bonds involve a polar interaction between carbon and an electronegative heteroatom (e.g., oxygen or nitrogen).
Lone pairs on
𝑍 can make these sites reactive with electrophiles or protons.
Examples:
Diethyl Ether: Contains a single oxygen atom connected to two carbons.
Chloroethane: An alkyl halide used as a local anesthetic.
Hemibrevetoxin B: A complex molecule containing multiple ether and functional groups.
Why is the carbon atom in a C–Z bond considered electron-deficient?
The electronegative heteroatom
𝑍 pulls electron density away from the carbon.
How do lone pairs on
𝑍 atoms affect the reactivity of compounds with C–Z bonds?
They can participate in reactions with protons and electrophiles.
They can participate in reactions with protons and electrophiles.
What is the functional group in diethyl ether?
An ether group (
−𝑂−).
Why is hemibrevetoxin B more reactive than diethyl ether?
A: It contains multiple ether groups and other functional groups, increasing its chemical complexity and reactivity.
What type of bonding is present in polyethylene?
A: Polyethylene consists of strong covalent C–C single bonds (sigma bonds) and C–H bonds.
Why is polyethylene classified as an alkane?
It contains only single bonds between carbon atoms and no functional groups.
What is the repeating unit in the structure of polyethylene?
The repeating unit in polyethylene is –CH₂–.
Why is polyethylene considered chemically inert?
Its structure lacks polar bonds or reactive functional groups, making it resistant to chemical reactions.
Its structure lacks polar bonds or reactive functional groups, making it resistant to chemical reactions.
How does the long-chain structure of polyethylene affect its physical properties?
The long chains contribute to its high molecular weight, strength, and resistance to degradation.
Why is polyethylene not reactive with Lewis acids or bases?
Polyethylene lacks electron-donating or electron-withdrawing functional groups required for interactions with Lewis acids or bases.
Could polyethylene act as a nucleophile in any reaction? Why or why not?
No, polyethylene cannot act as a nucleophile because it does not have lone pairs or electron-rich sites.
Why does polyethylene not engage in hydrogen bonding?
Polyethylene lacks polar bonds like O–H or N–H, which are necessary for hydrogen bonding.
What functional groups are present in polyethylene?
Polyethylene has no functional groups, only hydrocarbon chains.
How does the absence of functional groups in polyethylene impact its environmental persistence?
A: Without functional groups, polyethylene does not undergo chemical degradation, leading to its persistence in landfills.
What type of reactions can be used to modify polyethylene for functional purposes?
A: Reactions like free radical substitution can introduce functional groups into polyethylene.
Why is polyethylene used in packaging and insulation?
A: Its chemical stability, non-reactivity, and flexibility make it ideal for such applications.
What type of bond exists between carbon and the heteroatom
𝑍 in the diagram?
A polar covalent bond exists due to the electronegativity difference between carbon and
𝑍.
Why is the carbon atom labeled as electron-deficient in a C–Z bond?
The electronegative heteroatom
𝑍 pulls electron density away from the carbon, creating a partial positive charge (
𝛿+
δ +) on carbon.
What causes the heteroatom
𝑍 to have a partial negative charge (𝛿
− )?
A: The electronegativity of
𝑍 allows it to attract shared electrons more strongly, resulting in a partial negative charge.
How does the lone pair on
𝑍 affect the geometry of the molecule?
The lone pair on
𝑍 can repel bonding pairs of electrons, influencing the molecular geometry, such as bending or tetrahedral shapes.
What type of bond connects the oxygen atom to the carbon atoms in diethyl ether?
A: Covalent single (σ) bonds.
How many lone pairs of electrons are present on the oxygen atom in diethyl ether?
A: Two lone pairs of electrons.
A: Two lone pairs of electrons.
What structural feature makes hemibrevetoxin B more complex than diethyl ether?
A: Hemibrevetoxin B contains multiple functional groups, including hydroxyl (-OH), ether (-O-), and carbonyl (C=O) groups, as well as a larger carbon framework.
How does the cyclic structure in hemibrevetoxin B influence its chemical properties compared to diethyl ether?
A: The cyclic structure adds rigidity, potential for stereoisomerism, and specific interaction points for biological or chemical reactivity.
Why is diethyl ether classified as a simple ether while hemibrevetoxin B is not?
A: Diethyl ether contains only one ether group (-O-) between two ethyl groups, while hemibrevetoxin B contains multiple ether and additional functional groups.
Q: Why is the oxygen atom in both diethyl ether and hemibrevetoxin B considered a Lewis base?
A: The oxygen atom has lone pairs of electrons that can be donated to an electrophile.
What makes the carbonyl group in hemibrevetoxin B a reactive site for nucleophiles?
A: The carbonyl group (C=O) is polarized, making the carbon electron-deficient (
𝛿+), which attracts nucleophiles.
Q: How might the oxygen atoms in hemibrevetoxin B interact with protons in an acidic environment?
A: The lone pairs on the oxygen atoms can accept protons, acting as Lewis bases.
Why is diethyl ether less reactive toward acids and electrophiles than hemibrevetoxin B?
A: Diethyl ether lacks additional reactive functional groups like hydroxyl (-OH) or carbonyl (C=O), making it chemically less versatile.
: Identify the functional groups present in hemibrevetoxin B.
A: Hemibrevetoxin B contains ether (-O-), hydroxyl (-OH), and carbonyl (C=O) groups.
What is the primary functional group in diethyl ether?
A: The ether (-O-) group.
.
How does the presence of hydroxyl (-OH) groups in hemibrevetoxin B affect its solubility in water?
A: The hydroxyl groups can form hydrogen bonds with water, increasing solubility compared to diethyl ether.
How does the carbonyl group in hemibrevetoxin B contribute to its biological activity?
A: The carbonyl group is a reactive site that can participate in interactions with enzymes or other biological molecules.
What type of chemical reaction could diethyl ether undergo?
Diethyl ether can undergo oxidation or react with strong acids under specific conditions.
Why is hemibrevetoxin B likely to exhibit higher chemical reactivity than diethyl ether?
A: Hemibrevetoxin B contains multiple reactive functional groups (e.g., hydroxyl and carbonyl) that allow it to participate in a variety of chemical reactions.
In what type of reaction could the ether groups in hemibrevetoxin B participate?
A: The ether groups could participate in cleavage reactions in the presence of strong acids.
What makes hemibrevetoxin B a potential biologically active compound?
A: Its multiple functional groups and complex structure enable interactions with biological molecules, possibly affecting physiological pathways
Which functional group in hemibrevetoxin B is likely responsible for its biological activity?
A: The carbonyl group (C=O) is likely a key site for interactions with biological molecules.
How would the reactivity of hemibrevetoxin B change if its hydroxyl groups were removed?
: Removing the hydroxyl groups would reduce hydrogen bonding and decrease its reactivity and solubility in polar solvents like water.
Compounds Containing C–Z σ Bonds
compounds Containing a C=O Group (Carbonyl Group)
Reactivity of Carbonyl Group:
Polarization: The carbonyl group (C=O) is polarized due to the electronegativity of oxygen, making carbon an electrophilic center.
Features: Lone pairs on oxygen act as a Lewis base, while the carbon atom acts as a Lewis acid. The π bond in the carbonyl is more easily broken than a C–O single bond.
Examples:
Atenolol: Contains functional groups like aromatic rings, ether, amine, and alcohol. It is used as a β-blocker for treating hypertension.
Donepezil: Contains aromatic rings, ether, amine, and alcohol groups and is used for Alzheimer’s disease treatment.
Atenolol: Contains functional groups like aromatic rings, ether, amine, and alcohol. It is used as a β-blocker for treating hypertension.
Donepezil: Contains aromatic rings, ether, amine, and alcohol groups and is used for Alzheimer’s disease treatment.
What type of bond characterizes compounds containing C–Z σ bonds?
A: A polar covalent bond between carbon and a heteroatom
𝑍
Z.
Why is the carbon atom in a C–Z σ bond considered electron-deficient?
.
A: The heteroatom
𝑍
Z is more electronegative and pulls electron density away from carbon
What makes the π bond in a carbonyl group more reactive than a C–O σ bond?
A: The π bond is weaker and more easily broken in chemical reactions.
What functional group is present in alkyl halides?
A: The halo group (−X).
Name the functional group in ethers and provide an example.
A: The alkoxy group (−OR); example: CH₃OCH₃.
What is the functional group present in thiols?
A: The mercapto group (−SH).
Identify at least three functional groups in atenolol.
Aromatic ring, ether, amine, and alcohol.
What functional groups are common in both atenolol and donepezil?
A: Aromatic ring, ether, amine, and alcohol.
Why does the carbonyl carbon in C=O bonds act as an electrophile?
A: The carbon atom is electron-deficient due to the electronegativity of oxygen, making it susceptible to nucleophilic attack.
How do lone pairs on oxygen in the carbonyl group affect its reactivity?
A: They allow the oxygen atom to act as a Lewis base and interact with electrophiles or protons.
Q: What makes alkyl halides reactive in nucleophilic substitution reactions?
A: The polarized C–X bond makes the carbon susceptible to attack by nucleophiles.
: Which functional group in atenolol and donepezil allows for hydrogen bonding with water?
A: The alcohol group (−OH).
How does the halogen in alkyl halides act as a leaving group in chemical reactions?
A: The halogen is electronegative, creating a polar bond that makes it a stable leaving group during substitution or elimination reactions.
What makes the sulfur atom in thiols and sulfides a potential nucleophile?
A: The sulfur atom has lone pairs of electrons and lower electronegativity compared to oxygen, making it more nucleophilic.
Why are amines (
𝑅3N) classified as Lewis bases?
A: Amines have a lone pair of electrons on nitrogen that can be donated to an electrophile.
How does the polarity of the C–Z bond affect the electrophilicity of the carbon atom?
A: The more polar the C–Z bond, the greater the electron deficiency of the carbon atom, making it more electrophilic
Name the functional group in thiols and its distinguishing feature.
A: The mercapto group (−SH), characterized by the sulfur atom.
Why are alkyl halides reactive in nucleophilic substitution reactions?
A: The polar C–X bond makes the carbon atom electron-deficient and susceptible to nucleophilic attack.
How does the hydroxy group in alcohols affect their solubility in water?
A: The hydroxy group can form hydrogen bonds with water molecules, increasing solubility.
What makes ethers less reactive than alcohols in most chemical reactions?
A: Ethers lack a hydroxyl hydrogen, making them less acidic and less likely to participate in proton-transfer reactions
What makes the aromatic rings in donepezil less likely to act as nucleophiles?
A: The delocalized π-electrons are stabilized by resonance, reducing their availability for nucleophilic attack.
Identify the functional groups in atenolol.
Aromatic ring, amide (−CONH
2), ether (−O−), alcohol (−OH), and amine (−NH).
What functional groups are present in donepezil?
Aromatic ring, ketone (−C=O), ether (−O−), and amine (−N)
How does the presence of multiple ether groups in donepezil affect its chemical properties?
The ether groups increase the molecule’s hydrophobicity and contribute to its solubility in organic solvents
Problem 3.41: Predict the water solubility of each organic molecule
a) Caffeine
Prediction: Highly water-soluble.
Reason: Caffeine contains multiple polar groups, including carbonyl groups (C=O) and nitrogen atoms with lone pairs, which can form hydrogen bonds with water. Its structure makes it highly hydrophilic despite its aromatic rings.
b) Mestranol
Prediction: Poorly water-soluble.
Reason: Mestranol is mostly hydrophobic due to its large steroid structure with nonpolar rings. Although it has a hydroxyl (-OH) group and a methoxy (-OCH3) group, these polar regions are insufficient to overcome the molecule’s predominantly hydrophobic character.
c) Sucrose (table sugar)
Prediction: Highly water-soluble.
Reason: Sucrose has numerous hydroxyl (-OH) groups that can form extensive hydrogen bonds with water, making it extremely hydrophilic and readily soluble in water.
d) Carotatoxin
Prediction: Poorly water-soluble.
Reason: Carotatoxin has a long hydrophobic carbon chain and only one hydroxyl (-OH) group. The large nonpolar region dominates, making it insoluble in water.
Summary of Water Solubility:
Highly water-soluble: Caffeine, sucrose.
Poorly water-soluble: Mestranol, carotatoxin
