Organic Chemistry: Structure and Isomerism

• Organic chemistry is the study of carbon-containing compounds' structure, properties, composition, reactions, and preparation; these compounds may also contain hydrogen, nitrogen, oxygen, halogens, phosphorus, silicon, and sulfur
• Organic compounds are ubiquitous, forming the foundation of all known life and constituting most known chemicals

Bonding Characteristics

• Carbon's ability to catenate enables stable chains and rings, explaining the large number of organic compounds
• Carbon commonly forms covalent bonds through electron sharing
• Carbon atoms typically form four covalent bonds
• Carbon can form single, double, or triple bonds

Isomerism

• Isomers are molecules sharing a molecular formula but differing in structural formulas
• Structural isomers differ in atomic connectivity
• Stereoisomers share connectivity but differ in spatial atom arrangement
• Enantiomers are non-superimposable mirror image stereoisomers
• Diastereomers are stereoisomers that are not enantiomers

Functional Groups

• Functional groups are specific atomic groups within molecules dictating characteristic chemical reactions
• Alkanes exclusively contain single bonds between carbon and hydrogen atoms
• Alkenes feature at least one carbon-carbon double bond
• Alkynes have at least one carbon-carbon triple bond
• Alcohols have a hydroxyl group (-OH) bonded to a carbon atom
• Ethers have an oxygen atom bonded to two alkyl or aryl groups (R-O-R')
• Aldehydes possess a carbonyl group (C=O) bonded to at least one hydrogen atom
• Ketones possess a carbonyl group (C=O) bonded to two alkyl or aryl groups
• Carboxylic acids feature a carboxyl group (-COOH)
• Esters include a carboxyl group with the hydrogen atom replaced by an alkyl or aryl group (-COOR)
• Amines include a nitrogen atom bonded to one, two, or three alkyl or aryl groups
• Amides include a nitrogen atom bonded to a carbonyl group

Nomenclature

• The International Union of Pure and Applied Chemistry (IUPAC) nomenclature provides a systematic way of naming organic chemical compounds
• The IUPAC name includes a prefix, parent, and suffix
• The parent name indicates the number of carbon atoms in the longest continuous chain
• The suffix indicates the principal functional group
• The prefix indicates substituents attached to the parent chain
• Parent chain numbering assigns the lowest possible numbers to substituents

Reactions

• Addition reactions add atoms or atomic groups to a molecule, typically at a multiple bond
• Elimination reactions remove atoms or atomic groups from a molecule, typically forming a multiple bond
• Substitution reactions replace one atom or atomic group with another
• Rearrangement reactions reorganize atoms and bonds within a molecule
• Oxidation reactions represent electron loss or an increased oxidation state
• Reduction reactions represent electron gain or a decreased oxidation state

Spectroscopy

• Spectroscopy studies electromagnetic radiation interaction with matter
• Nuclear Magnetic Resonance (NMR) spectroscopy informs about a molecule's carbon-hydrogen framework
• Infrared (IR) spectroscopy identifies functional groups in a molecule
• Mass spectrometry (MS) identifies a molecule's molecular weight and fragmentation pattern
• Ultraviolet-Visible (UV-Vis) spectroscopy informs about electronic transitions within a molecule

Alkanes

• Alkanes are saturated hydrocarbons with only single bonds
• Alkanes are relatively unreactive
• Alkanes undergo combustion, halogenation, and cracking reactions
• Cycloalkanes feature a carbon atom ring

Alkenes and Alkynes

• Alkenes and alkynes are unsaturated hydrocarbons containing double and triple bonds, respectively
• Alkenes and alkynes are more reactive than alkanes
• Alkenes and alkynes undergo addition reactions like hydrogenation, halogenation, hydrohalogenation, and hydration
• Alkenes and alkynes serve as essential building blocks in organic synthesis

Aromatic Compounds

• Aromatic compounds are cyclic, planar, conjugated compounds with exceptional stability
• Benzene represents the simplest aromatic compound
• Aromatic compounds participate in electrophilic aromatic substitution reactions
• Examples include nitration, sulfonation, halogenation, and Friedel-Crafts alkylation/acylation

Alcohols, Ethers, and Thiols

• Alcohols contain a hydroxyl (-OH) group
• Ethers contain an oxygen atom bonded to two alkyl or aryl groups
• Thiols contain a sulfhydryl (-SH) group
• Alcohols undergo reactions like oxidation, esterification, and dehydration
• Ethers are relatively unreactive
• Thiols are more reactive than alcohols because of the weaker S-H bond

Aldehydes and Ketones

• Aldehydes and ketones contain a carbonyl (C=O) group
• Aldehydes are more reactive than ketones
• Aldehydes and ketones undergo nucleophilic addition reactions
• Reactions include oxidation, reduction, and the Wittig reaction

Carboxylic Acids and Derivatives

• Carboxylic acids contain a carboxyl (-COOH) group
• Carboxylic acids are weak acids
• Derivatives include esters, amides, acid halides, and anhydrides
• Carboxylic acids undergo nucleophilic acyl substitution reactions
• Examples include esterification, amidation, and hydrolysis

Amines and Amides

• Amines contain a nitrogen atom bonded to one, two, or three alkyl or aryl groups
• Amines are basic
• Amides contain a nitrogen atom bonded to a carbonyl group
• Amides are relatively unreactive

Chirality

• Chirality describes molecules that are non-superimposable on their mirror images
• A chiral center involves an atom, usually carbon, bonded to four different groups
• Enantiomers are chiral molecule pairs that mirror each other
• Diastereomers are stereoisomers that are not mirror images

Reactions Mechanisms

• Reaction mechanisms detail the step-by-step sequence of elementary reactions dictating an overall chemical change
• Mechanisms involve electron movement, chemical bond formation, and breakage
• Common mechanistic elements include nucleophilic attack, leaving group departure, proton transfer, and carbocation rearrangements
• Free radicals are species featuring unpaired electrons and participate in certain reaction mechanisms