Introduction to functional groups in organic chemistry, including alkanes, alkenes, alcohols, and amines.
Definition: Saturated hydrocarbons, typically represented in linear, ring (cycloalkane), or branched structures.
Arrangement: Can be open chain (aliphatic) or cyclic.
Naming Convention:
Ends in "-ane" (e.g., methane, ethane, propane, etc.) based on the number of carbon atoms.
Formulas: General formula CNH2n+2 for non-cyclic alkanes.
Cyclic alkanes have 2 fewer protons in their formula.
Structural Characteristics:
All alkanes exhibit tetrahedral geometry with sp3 hybridization and bond angles of approximately 109.5 degrees.
Main alkane names derived from Latin numerical roots:
1 Carbon: Methane
2 Carbons: Ethane
3 Carbons: Propane
4 Carbons: Butane
5 Carbons: Pentane
6 Carbons: Hexane
7 Carbons: Heptane
8 Carbons: Octane
9 Carbons: Nonane
10 Carbons: Decane
Line Drawings: Simplified representation omitting hydrogen atoms attached to carbon.
Definition: Unsaturated hydrocarbons with at least one double bond between carbon atoms.
Properties:
Bond angle: Approximately 120 degrees due to sp2 hybridization, results in trigonal planar geometry.
Naming Convention:
Ends in "-ene" to denote the presence of a double bond.
E.g., Ethene, Propene, Butene, etc.
Geometry Implications:
Presence of double bond prohibits free rotation, leading to locked planar structure, meaning it can not rotate - important. Happens for any double bond.
Example: Ethene described as entirely flat.
Definition: Hydrocarbons with at least one triple bond between carbon atoms.
Properties:
Geometry is linear with approximately 180-degree bond angles due to sp hybridization.
Naming Convention:
Ends in "-yne" (e.g., Ethyne, Propyne).
General Structure of Names:
Prefix indicates the number of carbon atoms.
Suffix indicates the functional group.
Examples of naming functional groups:
Alcohol: "-ol"
Aldehyde: "-al"
Amine: "-amine"
Ketone: "-one"
Carboxylic acid: "-oic acid"
Definition: Organic compounds with the hydroxyl (-OH) functional group.
Properties:
Alcohols introduce polarity; more interaction with water leads to higher boiling points than corresponding alkanes.
Examples: Ethanol (liquid) vs. Ethane (gas).
Naming Variants:
Primary (1°), Secondary (2°), Tertiary (3°) alcohols based on the position of the -OH group on the carbon chain.
Common names (e.g., butyl alcohol, isobutyl alcohol).
Dipole-dipole Interactions: tje attraction betweeen the positive end of one dipole and the negative end of another
Hydrogen bonding: when the +ve end of one dipole is a H bonded to F,O,N (atoms of high electronegativity)
Definition: Organic compounds containing nitrogen with at least one lone pair and bonds to hydrogen or hydrocarbon chains.
Properties:
Amines are somewhat weak bases, can form hydrogen bonds, and are generally polar compounds.
Classification:
Primary (1°) if nitrogen is bonded to one carbon, Secondary (2°) to two, Tertiary (3°) to three, and Quaternary (4°) if nitrogen is bonded to four groups.
Example names: Methylamine, Ethylamine, Dimethylamine.
The understanding of alkanes, alkenes, alkynes, alcohols, and amines forms the basis for organic chemistry.
Familiarity with nomenclature, structural formulas, and hybridization helps comprehend the properties and reactivities of various organic compounds.