CHE110 Chapter 18 PowerPoint (1)

Introduction

  • Learning is a transformative process.

  • The following notes focus on the key concepts related to amines, alkaloids, and neurotransmitters as outlined in Chapter 18.

Structure and Bonding of Amines

Definitions

  • Amines: Organic nitrogen compounds classified by the number of alkyl groups attached to the nitrogen (N) atom.

    • Primary (1°) amine: Has 1 C—N bond.

    • Secondary (2°) amine: Has 2 C—N bonds.

    • Tertiary (3°) amine: Has 3 C—N bonds.

    • Quaternary (4°) amine: Has four bonds to carbon and carries a positive charge.

    • Lone pair on the N atom is often omitted in condensed structures.

Heterocyclic Amines

  • The N atom can also participate in heterocyclic ring structures, enhancing chemical diversity.

Focus on Health & Medicine

Stimulants

  • Caffeine and Nicotine: Natural alkaloids that act as stimulants on the central nervous system.

Alkaloids

Morphine and Related Compounds

  • Morphine: Derived from opium; effective pain reliever but highly addictive. It has been used for centuries.

    • Long-term use leads to increased tolerance (higher doses needed for the same effect).

  • Codeine: Found in smaller quantities in opium, used for less severe pain but is still addictive.

  • Heroin: A derivative of morphine; more potent with a higher addiction potential due to increased fat solubility (2-3 times more potent than morphine).

  • Chemical conversions: Both hydroxyl (OH) groups in morphine are converted to esters in heroin.

Chemical Nomenclature

Examples of Amines

  • Quaternary Ammonium Ion: An example with specific alkyl group attachments and a positive charge.

  • Piperidine: A six-membered ring containing one nitrogen atom.

  • Aniline: A benzene ring with an amino (NH2) group.

Physical Properties of Amines

Boiling Points and Intermolecular Forces

  • Diethyl Ether: Boiling point of 38°C.

  • One Butanamine: Boiling point of 78°C; NH2 group attached to a four-carbon chain increases its boiling point due to stronger intermolecular forces.

  • One Butanol: Boiling point of 118°C; OH group also increases boiling point.

Influence of Structure on Boiling Points

  • Tertiary amine: No N-H bond; boiling point is lower (38°C).

  • Secondary amine: Boiling point of 56°C, with one hydrogen attached to nitrogen.

Alkaloid Structure Characteristics

Morphine Molecular Structure

  • Morphine has a complex structure with multiple rings and double bonds, affecting its pharmacological properties.

  • Resemblance to phenethylamine, a common motif in psychoactive drugs.

Amines as Bases

Protonation and Formation of Ions

  • Ammonia (NH3) reacts with water to form ammonium ion (NH4+).

    • Similar process occurs for primary amines with one R group changing to a protonated form.

Example Reaction

  • Example of a specific amine reacting with HCl to form a positively charged nitrogen species.

Neurotransmitter Pathways

Biosynthesis Overview

  • Tyrosine to L-Dopa: Tyrosine is functionalized to form L-Dopa (addition of OH).

  • Dopamine Production: Removal of a carbon chain leads to the synthesis of dopamine. The addition of hydroxyl transforms dopamine into norepinephrine.

Fluoxetine and Sertraline Structures

  • Fluoxetine: Contains a specific 3-carbon structure with distinct aromatic groups.

  • Sertraline: Features a six-membered carbon ring structure, showcasing various substituents affecting its pharmacological activity.