Covers aliphatic hydrocarbons: alkanes, alkenes, alkynes and cycloalkanes, with their general formulas, hybridisation and bonding, and the IUPAC-style naming of alkanes, cycloalkanes and alkyl groups. It then goes through homologous series, constitutional isomers, chair and boat conformations of cyclohexane with axial and equatorial positions, and the physical and chemical properties and reaction types of each class. Radical substitution, electrophilic addition with Markovnikov and anti-Markovnikov rules, oxidation, combustion and polymerisation close the note, with a short high-yield summary.
Topic 19 of 42 in the MU Sofia syllabus for Chemistry (Dental Medicine, Year 1). The free AceMed note covers it in 18 sections, about 1,660 words (11 min of reading), with 16 flashcards.
In this note
Aliphatic hydrocarbons
Chemical bonding and hybridization models.
Nomenclature
Homologous series
Isomerism: constitutional isomers (chain and positional)
Conformation of cyclohexane.
Axial and equatorial substitutes.
Chemical properties of alkanes, alkenes and alkynes
Characteristic types of reactions.
Mechanism of radical substitution (SR).
Electrophilic addition reaction (АE).
Oxidation and combustion.
High Yield
General points
Alkenes – reactions (Electrophilic Addition, AE)
Alkynes – reactions
Cycloalkanes
Polymerization
Aliphatic hydrocarbons
Aliphatic Hydrocarbons:
Organic compounds consisting only of carbon (C) and hydrogen (H) atoms.
Characterized by chains of carbon atoms.
Types of Aliphatic Hydrocarbons:
Saturated Hydrocarbons (Alkanes):
Alkanes contain only single carbon-carbon (C-C) bonds and are saturated with hydrogen atoms.
They have the general formula CnH2n+2.
Alkanes exhibit sp3 hybridization in carbon atoms.
Unsaturated Hydrocarbons:
Unsaturated hydrocarbons contain one or more carbon-carbon double (C=C) or triple (C≡C) bonds.
a. Alkenes:
Alkenes contain at least one carbon-carbon double bond (C=C).
They have the general formula CnH2n.
Alkenes exhibit sp2 hybridization in carbon atoms.
b. Alkynes:
Alkynes contain at least one carbon-carbon triple bond (C≡C).
They have the general formula CnH2n-2.
Alkynes exhibit sp hybridization in carbon atoms.
Draw this :
Chemical bonding and hybridization models.
Saturated Hydrocarbons (Alkanes):
Alkanes consist of single carbon-carbon (C-C) bonds and are saturated with hydrogen atoms.
In alkanes, each carbon atom forms four single bonds, resulting in tetrahedral geometry around each carbon atom.
The bonding in alkanes is described by the concept of sigma (σ) bonds, which are formed by the overlap of atomic orbitals.
The carbon atoms in alkanes exhibit sp3 hybridization, where one s orbital and three p orbitals hybridize to form four equivalent sp3 hybrid orbitals.
Unsaturated Hydrocarbons:
Unsaturated hydrocarbons contain one or more carbon-carbon double (C=C) or triple (C≡C) bonds, leading to fewer hydrogen atoms per carbon atom compared to alkanes.
Alkenes:
Alkenes contain at least one carbon-carbon double bond (C=C).
The carbon atoms in alkenes exhibit sp2 hybridization, where one s orbital and two p orbitals hybridize to form three equivalent sp2 hybrid orbitals.
The π (pi) bond in alkenes results from the sideways overlap of p orbitals above and below the plane of the carbon atoms.
Alkynes:
Alkynes contain at least one carbon-carbon triple bond (C≡C).
The carbon atoms in alkynes exhibit sp hybridization, where one s orbital and one p orbital hybridize to form two equivalent sp hybrid orbitals.
Alkynes have one σ bond and two π bonds, formed by the overlap of p orbitals above and below the plane of the carbon atoms.
Cycloalkanes:
Cycloalkanes are aliphatic hydrocarbons in which carbon atoms form a closed ring structure.
The bonding in cycloalkanes follows the same principles as alkanes, with each carbon atom forming four single bonds and exhibiting sp3 hybridization.
The ring structure introduces additional strain, leading to variations in bond angles and reactivity compared to straight-chain alkanes.
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