Alkanes, Cycloalkanes, and Structural Isomerism

Recognizing Alkanes and Cycloalkanes

Alkanes and cycloalkanes are saturated hydrocarbons, meaning they contain only single bonds between carbon atoms. Their general formulas are essential for identifying and naming these compounds.

• Alkane General Formula:

• Cycloalkane General Formula:

• Structural Isomers vs. Conformers: Isomers have the same molecular formula but different connectivity; conformers differ by rotation around single bonds.

Naming Alkanes and Cycloalkanes

Nomenclature follows IUPAC rules, using prefixes for the number of carbons and suffixes for functional groups.

• Prefixes: meth-, eth-, prop-, but-, pent-, hex-, hept-, oct-, non-, dec-

• Common Substituent Names: methyl, ethyl, propyl, isopropyl, butyl, fluoro, chloro, bromo, iodo

Reactions of Alkanes

Alkanes primarily undergo combustion reactions, producing carbon dioxide and water.

• Combustion:

Alkenes, Alkynes, and Aromatics

Recognizing Alkenes, Alkynes, and Aromatics

Alkenes and alkynes are unsaturated hydrocarbons containing double and triple bonds, respectively. Aromatics are cyclic compounds with alternating double and single bonds.

• Alkene: Contains at least one C=C double bond. Suffix: -ene

• Alkyne: Contains at least one C≡C triple bond. Suffix: -yne

• Aromatic: Six-carbon ring with alternating double and single bonds (e.g., benzene).

Naming Alkenes, Alkynes, and Aromatics

• Alkenes: Number the chain to give the double bond the lowest possible number.

• Alkynes: Number the chain to give the triple bond the lowest possible number.

• Aromatics: Use "benzene" as the parent name; substituents are named as prefixes.

Reactions of Alkenes and Alkynes

Alkenes and alkynes undergo addition reactions, including hydrogenation and hydration.

• Hydrogenation: Addition of hydrogen () across double or triple bonds.

• Hydration: Addition of water (), typically in the form of -H and -OH.

Alcohols, Ethers, Aldehydes, Ketones, and Thiols

Recognizing and Naming Alcohols, Ethers, Aldehydes, Ketones, and Thiols

Functional groups define the chemical properties and reactivity of organic molecules.

Properties and Reactions of Alcohols

• Classification: Primary (1°), secondary (2°), tertiary (3°) based on the number of alkyl groups attached to the carbon bearing the -OH group.

• Dehydration: Removal of water to form alkenes.

• Oxidation:

  • Alcohols to aldehydes (1°) or ketones (2°)

  • Aldehydes to carboxylic acids

  • Thiols to disulfides

• Reduction: Aldehydes and ketones can be reduced to alcohols.

Carbohydrates: Structure and Classification

Types of Carbohydrates

Carbohydrates are classified based on the number of sugar units.

• Monosaccharide: Single sugar unit

• Disaccharide: Two sugar units

• Polysaccharide: Many sugar units

Classifying Monosaccharides

• Number of Carbons: Triose (3), tetrose (4), pentose (5), hexose (6)

• Aldose: Contains an aldehyde group

• Ketose: Contains a ketone group

Chirality in Carbohydrates

Chirality is a key concept in carbohydrate chemistry, affecting their biological function.

• Chiral Carbon: Carbon atom with four different groups attached

• Stereoisomers: Molecules with the same connectivity but different spatial arrangement

• Enantiomers: Non-superimposable mirror images

• Fischer Projections: Two-dimensional representation of three-dimensional molecules

• D vs. L Assignment: Based on the position of the -OH group on the chiral carbon furthest from the carbonyl

Cyclic Forms and Mutarotation

• Haworth Structures: Depict cyclic forms of monosaccharides

• Mutarotation: Interconversion between alpha and beta anomers

Reactions of Carbohydrates

• Reduction of Carbonyl: Converts C=O to alcohol, producing sugar alcohols

• Oxidation of Aldehyde: Produces sugar acids

• Dehydration: Links monosaccharides via glycosidic bonds

Disaccharides and Polysaccharides

• Disaccharides: Formed by two monosaccharides (e.g., maltose, lactose, sucrose)

• Polysaccharides: Long chains of monosaccharides (e.g., starch, glycogen, cellulose)

• Starch: Composed of amylose and amylopectin

Summary Table: Organic Functional Groups

Example: Naming a Simple Alkane

• Example: CH4 is named methane; C2H6 is ethane.

Example: Identifying a Chiral Carbon

• Example: In glucose, the second carbon is chiral because it is attached to four different groups.

Additional info: Academic context and explanations have been expanded for clarity and completeness, including inferred details about reactions and functional group properties.