Chapter 8: Noncovalent Intermolecular Interactions, Nomenclature, and Properties of Alkyl Halides, Alcohols, Thiols, Ethers, and Sulfides

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Noncovalent Intermolecular Interactions and Organic Compound Classification

Overview of Chapter 8 Topics

This chapter introduces the classification, nomenclature, and physical properties of several important organic functional groups: alkyl halides, alcohols, thiols, ethers, and sulfides. It also explores noncovalent intermolecular interactions and their impact on boiling points, melting points, and solubility.

Functional Group Definitions
Nomenclature (IUPAC and Common)
Physical Properties (boiling/melting points, solubility)
Noncovalent Interactions (hydrogen bonding, dipole-dipole, van der Waals)

Functional Groups: Definitions and Classification

Key Organic Functional Groups

Organic compounds are classified by the presence of specific functional groups, which determine their chemical behavior.

Alkyl Halides: Compounds where a halogen (F, Cl, Br, I) is bonded to an alkyl group.
Alcohols: Compounds with a hydroxy group (–OH) attached to an alkyl group.
Thiols: Compounds with a thiol group or sulfhydryl group (–SH) attached to an alkyl group.
Ethers: Compounds in which an oxygen atom is bonded to two alkyl or aryl groups (R–O–R').
Sulfides: Sulfur analogs of ethers (R–S–R').

Example: Ethyl chloride (CH3CH2Cl) is an alkyl halide; methanol (CH3OH) is an alcohol.

Alcohols, Phenols, and Enols: Key Distinctions

Types of Hydroxy-Containing Compounds

The position and bonding of the –OH group define the type of compound:

Alcohol: –OH bonded to an sp3-hybridized carbon (alkyl carbon).
Phenol: –OH bonded to a carbon of a benzene ring (aromatic carbon).
Enol: –OH bonded to a carbon that is part of a double bond (alkenyl carbon).

Example: Phenol (C6H5OH), vinyl alcohol (enol), ethanol (alcohol).

Classification of Alkyl Halides and Alcohols

Primary, Secondary, and Tertiary Structures

Alkyl halides and alcohols are classified based on the number of alkyl groups attached to the α-carbon (the carbon bonded to the functional group).

Primary (1°): α-carbon attached to one alkyl group.
Secondary (2°): α-carbon attached to two alkyl groups.
Tertiary (3°): α-carbon attached to three alkyl groups.

Example: Methanol is a primary alcohol; isopropanol is a secondary alcohol.

Nomenclature of Organic Compounds

IUPAC Naming Rules

Systematic naming ensures clarity and consistency in organic chemistry. The following steps outline the IUPAC approach:

Identify the principal group (highest priority functional group, e.g., –OH or –SH).
Select the principal chain (longest chain containing the principal group).
Number the chain to give the principal group the lowest possible number.
Identify and number substituents (other groups attached to the chain).
Assemble the name by citing the principal group, its position, and substituents in alphabetical order.

Example: 2-butanol (butan-2-ol), 3-chloro-2-pentene.

Common and IUPAC Names of Alkyl Halides

Naming Alkyl Halides

Alkyl halides are named by identifying the alkyl group and the halide:

Common Name: Alkyl group + halide (e.g., ethyl chloride, butyl bromide).
IUPAC Name: Halogen as a substituent (fluoro-, chloro-, bromo-, iodo-) on the parent hydrocarbon chain.

Example: 2-chloroethane, bromocyclohexane, 3-ethyl-4-iodohexane.

Nomenclature of Alcohols

Common and Systematic Naming

Alcohols are named by identifying the alkyl group attached to the –OH and adding 'alcohol' (common) or using the suffix '-ol' (IUPAC).

Common Names: isopropyl alcohol, cyclohexyl alcohol, allyl alcohol, benzyl alcohol.
IUPAC Names: Use the parent alkane name, replace '-e' with '-ol', and number the position of –OH.

Example: 1-propanol, 2-propanol (isopropanol).

Additional info:

Further topics in the chapter (not shown in images) include nomenclature of thiols, ethers, and sulfides, physical properties (boiling/melting points, solubility), and noncovalent interactions such as hydrogen bonding, dipole-dipole, and van der Waals forces.
Understanding nomenclature and classification is foundational for predicting reactivity and properties in organic chemistry.