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 useful for identifying and classifying these compounds.

• Alkane General Formula:

• Cycloalkane General Formula:

• Structural Isomers: Compounds with the same molecular formula but different connectivity of atoms.

Example: Butane () and isobutane are structural isomers.

Naming Alkanes and Cycloalkanes

Systematic nomenclature is essential for clear communication in organic chemistry. The IUPAC system uses prefixes and suffixes to indicate the number of carbons and the type of hydrocarbon.

• Prefixes for 1–10 carbons: meth-, eth-, prop-, but-, pent-, hex-, hept-, oct-, non-, dec-

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

Example: 2-chloropropane

Reactions of Alkanes

Alkanes primarily undergo combustion reactions, where they react with oxygen to produce 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: Double bonded carbons, ends in -ene

• Alkyne: Triple bonded carbons, ends in -yne

• Aromatic: Six carbon ring with alternating double and single bonds

Naming Alkenes, Alkynes, and Aromatics

Naming follows similar rules as alkanes, with suffixes indicating the type of bond.

• Alkene: Suffix -ene

• Alkyne: Suffix -yne

• Aromatic: Often named as benzene derivatives

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 (in the form of -H and -OH)

Example: Ethene () + → Ethane ()

Alcohols, Ethers, Aldehydes, Ketones, and Thiols

Recognizing and Naming Functional Groups

Functional groups determine the chemical properties and reactivity of organic molecules. The table below summarizes key functional groups and their naming conventions.

Properties and Reactions of Alcohols

Alcohols are classified as primary, secondary, or tertiary based on the number of carbon atoms attached to the carbon bearing the hydroxyl group.

• Primary Alcohol: degree

• Secondary Alcohol: degree

• Tertiary Alcohol: degree

Alcohols undergo several important reactions:

• Dehydration: Removal of water to form alkenes

• Oxidation: Converts alcohols to aldehydes, ketones, or carboxylic acids

Example: Oxidation of ethanol () to acetaldehyde ()

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

Monosaccharides are further classified by the number of carbons and the type of carbonyl group present.

• Aldose: Contains an aldehyde group

• Ketose: Contains a ketone group

Chirality in Carbohydrates

Chirality is a key concept in carbohydrate chemistry, as many sugars have chiral centers.

• Chiral Carbon: Carbon atom with four different groups attached

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

• Enantiomers: Non-superimposable mirror images

Example: D-glucose and L-glucose

Fischer Projections and Haworth Structures

Fischer projections are used to represent the 3D arrangement of atoms in sugars. Haworth structures depict the cyclic forms of monosaccharides.

• Fischer Projection: 2D representation of chiral molecules

• Haworth Structure: Cyclic form of monosaccharides

• Mutarotation: Interconversion between alpha and beta anomers

Reactions of Carbohydrates

Carbohydrates undergo reduction and oxidation reactions, as well as dehydration to form glycosidic bonds.

• Reduction of Carbonyl: Converts carbonyl group to alcohol

• Oxidation of Sugar: Produces sugar acids

• Dehydration: Forms glycosidic bonds between monosaccharides

Disaccharides and Polysaccharides

Disaccharides are formed by linking two monosaccharides via glycosidic bonds. Polysaccharides are long chains of monosaccharide units.

• Disaccharides: Maltose, lactose, sucrose

• Polysaccharides: Starch (amylose, amylopectin), glycogen, cellulose

Example: Sucrose is composed of glucose and fructose.

Summary Table: Organic Functional Groups

Additional info: Some context and examples were inferred to provide a complete, self-contained study guide suitable for exam preparation.