Organic Chemistry: Functional Groups and Nomenclature — Chapters 1–7 (copy)
Chapter 1: Introduction
Opening questions: Are they constitutional? What are our constitutional isomers? Compounds with the same molecular formula but connected in different ways.
Example discussion: a diethyl group has the formula ext{C}4 ext{H}{10}.
Emphasis on isomerism: compounds with the same molecular formula can have different connectivity (constitution).
Boiling point intuition:
Butanol vs another isomer (same formula context used in discussion): butanol is higher because the hydroxyl (OH) group enables strong hydrogen bonding, increasing intermolecular forces and sticking molecules together more effectively.
The OH group increases boiling point due to hydrogen bonding; this is an example of how functional groups influence physical properties.
Phase changes and bonds:
Ice (water) ⇌ liquid water ⇌ steam all have the same molecular formula ext{H}_2 ext{O}; when heating, we do not break covalent bonds in the molecule, but rather separate molecules (intermolecular forces are overcome).
Clarification about bonds: covalent bonds are strong within a molecule; ionic bonds are strong between molecules; many times students confuse bond strength with intermolecular forces.
Lab/odor example:
Butyric acid has a very strong, unpleasant odor; its name relates to “butyro-” (butter) and is typically used to illustrate strong hydrogen bonding and polarity.
Transition to functional groups: today’s focus is on functional groups in organic chemistry – common structural themes that recur in chemistry and have specific names.
Functional group example: an arrangement like two CH₂ groups linked to an oxygen represents a common functional group with a specific bonding interaction.
Distinction: a lone hydroxyl group without other oxygens is a specific functional group (hydroxyl). If that OH is bound to a carbon that is double-bonded to oxygen, the group is associated with a carbonyl and the compound is not simply an alcohol but a carboxylic acid.
Chapter 2: Same Alkene Carbon
Prerequisites reviewed: Lewis structures, bottom-line (skeletal) structures, and basic hormone-related chemistry; the material snowballs quickly, so be ready to decipher structures.
Hydrocarbons overview:
Alkanes: hydrocarbons with no double or triple bonds; only single bonds.
Condensed formulas vs molecular formulas: condensed formula is a structural shorthand, not the molecular formula.
Linear alkanes: straight-chain hydrocarbons.
Branched alkanes: branched carbon chains with one or more alkyl substituents.
Substitution terminology:
A substituent is a smaller piece attached to a larger molecule.
An alkyl substituent is a hydrocarbon fragment with no double or triple bonds (i.e., derived from an alkane).
Generic R groups represent hydrocarbon substituents when discussing replacements on a parent chain.
Cycloalkanes:
Cyclic hydrocarbons with no double or triple bonds are still alkanes, but are named with cyclo- (e.g., cyclohexane, cyclopentane).
Cycloalkanes may be branched (e.g., a cycloalkane with a methyl substituent).
Nomenclature patterns:
Prefix cyclo- signals a cyclic structure; hexane → cyclohexane if cyclic.
Substituents include methyl groups as single-carbon branches.
Alkenes (C=C) and substitution patterns:
Unsubstituted alkene: no substituents on the double bond carbons.
Monosubstituted alkene: one alkyl substituent total on the double-bond carbons.
Disubstituted alkene: two alkyl substituents; can be on the same alkene carbon (geminal) or on opposite ends (trans/gem relations in line notation).
Trisubstituted alkene: three different alkyl substituents bound to the double bond carbons.
Tetrasubstituted (fully substituted) alkene: four alkyl substituents on the two double-bond carbons.
Bond-line perspective:
Bond-line drawings can illustrate monosubstituted, disubstituted, etc., by counting substituents attached to the alkene carbons.
Alkynes (C≡C) overview:
Suffix changes to “-yne” to indicate a carbon–carbon triple bond.
Terminal alkyne: at least one hydrogen on the terminal alkyne carbon; internal alkyne: both ends have alkyl substituents.
Counting carbons in bottom-line formulas can require accounting for implied carbons at the ends of lines (carbons not drawn explicitly except by terminal bonds).
Hybridization teaser: Monday’s session will dive into hybridization and how geometry and sigma/pi bonds affect structure and reactivity.
Chapter 3: Bonds To Carbon
Gist: In the class, R groups are treated as alkyl substituents (hydrocarbons, CHs) for simplicity; literature may specify more complex substituents, but for this course, R = alkyl substituent.
Substituted alkenes: methods to identify mono-, di-, tri-, tetra-substituted alkenes by counting substituents on the alkene carbons.
Example reasoning (practice discussion):
If you focus on the alkene carbons and count the carbons attached to them, you can determine substitution level.
In a given structure, if two alkyl substituents are attached to the double bond carbons and are on opposite ends, it’s disubstituted in that orientation; other distributions are possible (geminal, trans/cis considerations in line drawings).
Stability note: greater substitution on an alkene generally leads to greater stability/reactivity considerations in additions to alkenes.
Molecular formulas and constitutional isomers:
Structures with the same molecular formula can be constitutional isomers (same formula, different connectivity).
Alkynes recap (reiteration): alkynes have a C≡C triple bond; substitutions can be counted similarly for determining substitution patterns; terminal vs internal distinctions rely on the presence of hydrogens on the alkyne carbons.
Chapter 4: Primary Alkyl Chloride
Counting carbons and hydrogens in examples:
Determine molecular formula by counting visible carbons and implied hydrogens on terminal carbons.
Example assessment showed two six-carbon chains with different linkages and substituents, both yielding a formula of ext{C}6 ext{H}{10}, illustrating constitutional isomerism.
Gasoline note: some hydrocarbon mixtures are highly flammable; structural isomers can share formula but differ in properties.
Benzene and arenes:
Benzene is a famous aromatic compound with alternating single and double bonds in a six-membered ring.
Ethyl benzene is benzene with an ethyl substituent; “aromatic” or “aryl/aryne” designations apply to these rings.
Aromaticity criteria extend beyond simple alternating bonds and include stability considerations (delocalized electrons).
Haloalkanes (X denotes a halogen: F, Cl, Br, I):
A methyl haloalkane has a halogen on a methyl group (CH3–X).
Primary haloalkane: one hydrogen replaced by an alkyl substituent on the carbon bearing the halogen.
Secondary haloalkane: two hydrogens replaced by alkyl substituents on the halogen-bearing carbon.
Tertiary haloalkane: three alkyl substituents on the carbon bearing the halogen.
The “alpha carbon” term is used to refer to the carbon bearing the halogen; it is bonded to one or more additional carbons.
Example analyses:
A primary haloalkane: the alpha carbon has one additional carbon attached.
A tertiary haloalkane: the alpha carbon has three additional carbons attached.
Alcohols and hydroxyl terminology:
An OH group is called a hydroxyl.
Distinction between aliphatic alcohols (non-aromatic) and phenols (OH directly bonded to a benzene ring).
Phenols:
Hydroxyl group bound directly to a benzene ring is a phenol (e.g., phenol or metoprolol as example).
Nitrogen-containing groups:
Amines: derived from ammonia; classification by number of R groups bound to nitrogen (primary: 1 R, secondary: 2 R, tertiary: 3 R).
Commonly associated with strong, fishy odors.
Amides and amide linkage:
Amides contain a nitrogen attached to a carbonyl carbon (C=O); peptide linkages in proteins are amide bonds.
Ethers:
An ether features an oxygen bound to two alkyl groups (R–O–R); no additional classification by substitution beyond basic description.
Carbonyl-containing families:
Ketones: carbonyl carbon bonded to two alkyl substituents.
Aldehydes: carbonyl carbon bonded to at least one hydrogen; formaldehyde is the simplest aldehyde.
Carboxylic acids and derivatives:
Carboxylic acids: carbonyl carbon with an OH group (–COOH).
Esters: derived from carboxylic acids where the hydrogen of the OH is replaced by an alkyl group (R–CO–OR’); common in flavors and fragrances (e.g., ethyl acetate).
Ester examples and notes:
Ethyl acetate: common solvent; used in nail polish remover.
Esters contribute to scents and flavors; they are often intended to be pleasant.
Special note on naming and function:
Old terminology sometimes uses “carbonyl carbon” to refer to the carbon attached to the hydroxyl in alcohols when discussing reactivity; this usage is historical.
Chapter 5: A Primary Alcohol
Alcohols contain an OH group (hydroxyl).
Distinction: When the OH is bound to a carbonyl carbon, the compound is not an alcohol but a carboxylic acid; logic follows from the functional group present.
Alpha carbon terminology (revisited):
The carbon attached to the hydroxyl group is used to classify the alcohol as primary, secondary, or tertiary, similar to haloalkanes:
If the alpha carbon has three hydrogens (i.e., attached to no other carbons besides the hydroxyl-bearing carbon), it is a methyl group (e.g., primary alcohol if only one R group is attached to the OH-bearing carbon).
If the alpha carbon has one alkyl substituent, the alcohol is secondary; two substituents indicate tertiary;
Historical term: the carbon attached to the hydroxyl group was once called the carbonyl carbon in older literature.
Phenols vs aliphatic alcohols (revisited): phenols have OH directly attached to an aromatic ring (benzene) and behave differently in reactions and in acid-base chemistry.
Amine terminology (revisited): amines contain nitrogen; their classification by R groups bound to nitrogen (primary, secondary, tertiary) parallels the alcohol/haloalkane scheme.
Ether recap:
An ether is an O atom between two alkyl groups (R–O–R); no further substitution classification for ethers in this lecture.
Carbonyl-containing substances: reiteration of aldehydes, ketones, carboxylic acids, esters, amides, and nitriles.
Practical lab note: next week’s lab will separate aliphatic alcohols from phenols; phenols have OH bound directly to a benzene ring, which differentiates them from aliphatic alcohols.
Chapter 6: Many Carbon Carbonyl
Ketones and aldehydes (revisited):
Ketone: carbonyl carbon bonded to two alkyl substituents.
Aldehyde: carbonyl carbon bonded to at least one hydrogen (formaldehyde is the simplest example).
In line formulas, hydrogens are often shown on the carbonyl carbon to remind their presence, even if not drawn explicitly.
Carboxylic acids and derivatives recap:
Carboxylic acids: carbonyl carbon double-bonded to oxygen and single-bonded to OH.
Esters: carboxylic acid derivatives where OH is replaced by an alkyl group (R–CO–OR’).
Amides: nitrogen attached to the carbonyl carbon (–CONR2) and play a major role in biology via peptide linkages.
Nitriles (cyanides): carbon triple-bonded to nitrogen (–C≡N); formed via reaction of haloalkanes with cyanide; nitriles are also called cyanides.
Aromatic and arenes: refamiliarize with benzene-like rings; arenes show aromatic stability with delocalized electrons.
Practical examples and lab relevance:
Ethyl acetate as a common solvent and fragrance/flavor context;
Methyl benzoate (fragrance compound) derived from benzoic acid with a methyl group; flavors and fragrances connection mentioned.
Summary of key functional groups encountered:
Alcohols (aliphatic) vs phenols
Ethers
Aldehydes and ketones
Carboxylic acids and esters
Amides and nitriles
Amines
Aromatic rings (arenes) and substituted arenes
Reactions and biology links:
Peptide bonds are amide linkages in proteins.
Esters and amides have broad relevance in chemistry, biology, flavors, and fragrances.
Quick practice prompt reference (conceptual): identify carboxylic acid, haloalkane, amine, ester, and arene in a complex structure; this helps reinforce functional-group recognition.
Substructure count exercise and substituted alkene analysis reminders were used to build familiarity with the governing rules for substitution patterns (mono-, di-, tri-, tetra-substituted alkenes).
Chapter 7: Conclusion
Quick recap questions used to check understanding of functional groups in a complex molecule:
How many hydroxyl groups are present? (Answer: 1)
How many carbonyls (C=O) are present? (Answer: 2)
Is the amine primary, secondary, or tertiary in the shown structure? (Answer: Primary for the example provided)
For the nitro/amine-like fragment: is it secondary or tertiary? (Answer depends on the specific N-substitution shown.)
How many carbonyls are present? (2)
Is the alkyne terminal or internal? (Terminal in the discussed example)
Final notes and study strategy:
Flashcards for functional groups can be a helpful study tool; practice recognizing each group and its basic reactivity.
For the naming conventions, keep track of primary/secondary/tertiary classifications for haloalkanes, alcohols, and amines as they commonly appear in problems.
On Monday, a shift to hybridization will occur, which will clarify geometry, sigma vs pi bonds, and how geometry impacts molecular properties.
Quick closing thought:
The course integrates structure, naming, and reactivity to build intuition about why certain molecules behave the way they do in lab settings, including separation tasks and reactivity studies.
Key formulas and concepts mentioned throughout the notes
Molecular formula examples used in the lecture:
Diethyl group: ext{C}4 ext{H}{10}
A set of compounds discussed with formula ext{C}6 ext{H}{10} to illustrate constitutional isomers.
Water/steam references to illustrate phase changes without breaking covalent bonds: ext{H}_2 ext{O} in all three phases.
Common solvent/ester example: ext{CH}_3 ext{COOEt} (ethyl acetate) as an ester; referenced for lab contexts and fragrance applications.
Aromatic compounds: benzene-like ring structures with alternating single and double bonds; represented in shorthand as arenes.
If you want, I can extract key exam-ready flashcards from these notes (functional groups, substitution patterns, and examples) or create a condensed one-page summary focusing on the most test-relevant points.