Organic Chemistry Intro

Organic chemistry is the study of carbon-containing compounds, which form the basis of life and countless materials. Carbon’s unique ability to form long chains, rings, and multiple bonds (single, double, triple) with itself and other elements like hydrogen, oxygen, and nitrogen results in millions of compounds. From methane in natural gas to complex proteins, organic chemistry is everywhere. This article covers hydrocarbons, functional groups, naming conventions, and practical applications.

Hydrocarbons

Hydrocarbons are organic compounds composed solely of carbon and hydrogen, classified into three main types:

  • Alkanes: Single bonds, general formula \( \ce{C_nH_{2n+2}} \). Example: Methane (\( \ce{CH4} \)), ethane (\( \ce{C2H6} \)). Saturated (max H atoms).
  • Alkenes: At least one double bond, \( \ce{C_nH_{2n}} \). Example: Ethene (\( \ce{C2H4} \)), \( \ce{CH2=CH2} \). Unsaturated.
  • Alkynes: At least one triple bond, \( \ce{C_nH_{2n-2}} \). Example: Ethyne (\( \ce{C2H2} \)), \( \ce{HC#CH} \). Unsaturated.

Aromatic hydrocarbons like benzene (\( \ce{C6H6} \)) have ring structures with alternating double bonds, exhibiting unique stability.

Functional Groups

Functional groups are specific atom arrangements that determine a compound’s reactivity:

  • Alcohols: \( \ce{-OH} \). Example: Ethanol (\( \ce{CH3CH2OH} \)), in beverages.
  • Carboxylic Acids: \( \ce{-COOH} \). Example: Acetic acid (\( \ce{CH3COOH} \)), in vinegar.
  • Amines: \( \ce{-NH2} \). Example: Methylamine (\( \ce{CH3NH2} \)).
  • Esters: \( \ce{-COOR} \). Example: Ethyl acetate (\( \ce{CH3COOCH2CH3} \)), in fragrances.

These groups enable diverse reactions, like esterification: \( \ce{CH3COOH + CH3CH2OH -> CH3COOCH2CH3 + H2O} \).

Nomenclature

IUPAC naming systematically identifies compounds:

  1. Identify the longest carbon chain (root: meth-, eth-, prop-, etc.).
  2. Number the chain to give substituents the lowest numbers.
  3. Name substituents (e.g., methyl-, chloro-) and functional groups.

Example: \( \ce{CH3CH(CH3)CH2CH3} \):

  • 4 carbons: butane.
  • Methyl on carbon 2: 2-methylbutane.

Alkenes use -ene (e.g., \( \ce{CH2=CHCH3} \): propene).

Applications

Organic chemistry impacts:

  • Energy: Hydrocarbons in fuels (e.g., gasoline: \( \ce{C8H18} \)).
  • Medicine: Drugs like aspirin (\( \ce{C9H8O4} \)).
  • Materials: Polymers like polyethylene (\( \ce{-(CH2CH2)_n-} \)).
  • Food: Flavors, preservatives (e.g., esters).

It’s foundational to modern life and innovation.