Unsaturated Hydrocarbons in Organic Chemistry

Unsaturated Hydrocarbons

Contain double or triple bonds between carbon atoms.

Alkenes

Hydrocarbons with one or more double bonds (C=C).

Alkynes

Hydrocarbons with one or more triple bonds (C≡C).

Aromatic Hydrocarbons

Contain alternating double and single bonds in a ring.

General Formula for Alkenes

CnH2n, where n is the number of carbons.

IUPAC Naming

Systematic method for naming organic compounds.

Geometric Isomers

Isomers differing in spatial arrangement around double bonds.

Cis-Isomers

Similar groups on the same side of a double bond.

Trans-Isomers

Similar groups on opposite sides of a double bond.

Markovnikov's Rule

Predicts major products in addition reactions of alkenes.

Addition Reactions

Reactions where atoms are added to a double bond.

Addition Polymerization

Process of forming polymers by adding monomers together.

Uses of Addition Polymers

Commonly used in plastics and synthetic materials.

Naming Alkenes Steps

Identify longest chain, number carbons, locate double bond.

Multiple Double Bonds

Use -diene, -triene to denote number of double bonds.

sp2 Hybridization

Formation of three hybrid orbitals from one s and two p orbitals.

Bond Angles in Alkenes

120° angles between sp2 hybrid orbitals.

Sigma (σ) Bond

First bond formed by overlapping orbitals.

Pi (π) Bond

Second bond formed by overlapping unhybridized p orbitals.

Cis-Trans Stereoisomerism

Occurs in alkenes with two different groups on carbons.

Calculation of Isomers

Number of cis-trans isomers is 2^n, where n is double bonds.

Structural Formulas

Visual representations of molecular structures.

Physical Properties of Isomers

Cis and trans isomers have different physical properties.

Alkenes

Hydrocarbons with at least one double bond.

Physical Properties

Similar to alkanes; nonpolar, insoluble in water.

Alkene States

Gases with 4 C atoms; liquids 5-17 C; solids 18+ C.

Density

Alkenes are less dense than water.

Gasoline Odor

Low molecular weight alkenes smell like gasoline.

Alkene Reactivity

Alkenes are chemically reactive due to double bonds.

Addition Reactions

Compounds add to alkenes at double bonds.

Halogenation

Reaction with halogens forming haloalkanes.

Hydrogenation

Addition of hydrogen using catalysts like platinum.

Hydration

Water splits; H and OH attach to carbons.

Markovnikov's Rule

H attaches to carbon with more hydrogens.

Addition Polymers

Polymers formed from alkene addition reactions.

Polyethylene

Example of an addition polymer from alkenes.

Monomer

Starting material for polymer repeating units.

Copolymers

Polymers from two different monomers.

Alkynes

Hydrocarbons with at least one triple bond.

Ethyne

Simplest alkyne, used in torches and plastics.

sp Hybridization

Mixing of orbitals in alkynes for bonding.

Linear Shape

Alkynes have a linear geometry due to sp hybridization.

Alkyne Nomenclature

Alkynes named with -yne suffix.

Aromatic Compounds

Contain benzene rings or structural relatives.

Aliphatic Compounds

Non-aromatic organic compounds including alkenes.

Benzene Structure

Alternating single and double bonds in a ring.

Delocalized Electrons

Electrons move freely around benzene's double ring.

Phenyl Group

Benzene ring as part of a larger hydrocarbon.

Ortho, Meta, Para

Prefixes for substituent positions on benzene.

Substitution Reactions

Aromatic rings replace hydrogen with other groups.

Polycyclic Aromatic Compounds

Carcinogenic compounds with shared carbon atoms.

Aromatic Uses

Solvents and starting materials for valuable compounds.