Functional Group Chemistry 1
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Questions and Answers

Why is functional group chemistry considered important for pharmacy students?

  • It helps to simplify drug formulations.
  • It allows students to memorize chemical equations.
  • It focuses solely on the pharmacological effects of drugs.
  • It aids in understanding chemical structure and drug properties. (correct)

    • What role does a nucleophile play in organic reactions?

  • It donates electrons to form a bond with an electrophile. (correct)
  • It accepts electrons from another molecule.
  • It acts as a catalyst to accelerate reactions.
  • It enhances the stability of leaving groups.

    • Which of the following functionalities would be essential to identify in drug molecules for predicting their properties?

  • Metallic ions
  • Aromatic rings
  • Carbohydrates
  • Functional groups (correct)

    • What does hyperconjugation refer to in the context of radical stability?

    <p>Stabilization due to electron donation from adjacent sigma bonds.</p> Signup and view all the answers

    Which type of arrow is used to accurately denote bond making or breaking processes in organic chemistry?

    <p>Curly arrow</p> Signup and view all the answers

    What part of a drug molecule is typically responsible for most of the reactions and interactions?

    <p>Functional group</p> Signup and view all the answers

    Which characteristic is NOT associated with molecules having the same functional group?

    <p>Distinct reactivities</p> Signup and view all the answers

    Which process is linked to the absorption, distribution, metabolism, and excretion (ADME) of drugs?

    <p>Functional group interactions</p> Signup and view all the answers

    What does the hydrocarbon part of a drug molecule typically represent?

    <p>Inert portion</p> Signup and view all the answers

    Why is understanding functional groups important in drug design?

    <p>They influence receptor binding and drug properties.</p> Signup and view all the answers

    What determines the distribution patterns of substitution products in free-radical reactions?

    <p>Stability of intermediate radicals</p> Signup and view all the answers

    Which type of radical is formed when there are three carbon atoms bonded to the carbon with the unpaired electron?

    <p>Tertiary radical</p> Signup and view all the answers

    Which statement correctly describes hyperconjugation?

    <p>It increases stability through interaction with adjacent p or π orbitals</p> Signup and view all the answers

    The benzyl and allyl radicals exhibit greater stability than expected due to what phenomenon?

    <p>Resonance and delocalization of electrons</p> Signup and view all the answers

    What is the primary reason for the categorization of radicals into primary, secondary, and tertiary?

    <p>The number of carbon atoms bonded to the radical carbon</p> Signup and view all the answers

    What shape do sp3 hybridized carbon atoms adopt?

    <p>Tetrahedral</p> Signup and view all the answers

    How is the bond represented that points towards the observer?

    <p>Wedge bond</p> Signup and view all the answers

    Which type of molecules are particularly important when discussing chiral centers?

    <p>Chiral molecules</p> Signup and view all the answers

    In a chemical reaction mechanism, what does the symbol REACTANTS → PRODUCTS represent?

    <p>The conversion of reactants into products</p> Signup and view all the answers

    What type of reaction mechanism involves the movement of one electron at a time?

    <p>Radical</p> Signup and view all the answers

    What defines a nucleophile?

    <p>Electron-rich species</p> Signup and view all the answers

    In the context of reaction mechanisms, what does an electrophile do?

    <p>Accepts electrons</p> Signup and view all the answers

    Which type of bond typically signifies the movement of two electrons in a polar mechanism?

    <p>Double bond</p> Signup and view all the answers

    What is denoted by a single headed arrow in radical mechanisms?

    <p>Movement of one electron</p> Signup and view all the answers

    Which of the following describes the activation energy?

    <p>Energy difference between starting material and transition state</p> Signup and view all the answers

    What characterizes a transition state in a chemical reaction?

    <p>It has the highest energy along the reaction pathway</p> Signup and view all the answers

    What does the term 'lone pair' refer to in the context of electron-rich centers?

    <p>A pair of electrons not involved in bonding</p> Signup and view all the answers

    In a radical mechanism, what must occur to form a bond?

    <p>Two radicals must each donate one electron</p> Signup and view all the answers

    What is identified as a 'δ+' end of a polarized bond?

    <p>An electron-deficient part of a molecule</p> Signup and view all the answers

    What is the importance of studying mechanisms in chemistry?

    <p>To understand the energy changes within reactions</p> Signup and view all the answers

    What does a high energy peak in a reaction pathway indicate?

    <p>A transition state</p> Signup and view all the answers

    What is the general formula for alkanes?

    <p>C_nH_{2n+2}</p> Signup and view all the answers

    Which of the following characteristics is true about alkanes?

    <p>They have weak London dispersion forces.</p> Signup and view all the answers

    In alkanes, which process typically leads to the generation of radicals?

    <p>Halogenation</p> Signup and view all the answers

    What happens in the initiation step of a radical reaction during halogenation of alkanes?

    <p>A chlorine radical is formed.</p> Signup and view all the answers

    Which of the following statements about the stability of the ester formed during the reaction of amoxicillin is true?

    <p>It is stable to hydrolysis.</p> Signup and view all the answers

    What type of bonds do alkanes consist of?

    <p>Single bonds only</p> Signup and view all the answers

    In which scenario do alkanes typically react?

    <p>In the presence of chlorine or bromine</p> Signup and view all the answers

    How do the melting and boiling points of alkanes behave with increasing molecular weight?

    <p>They increase.</p> Signup and view all the answers

    Which of the following best describes the solubility of alkanes in water?

    <p>Virtually insoluble</p> Signup and view all the answers

    What is the primary product of alkane combustion?

    <p>CO2 and H2O</p> Signup and view all the answers

    What is the pKa value of alkanes, indicating their reactivity?

    <p>pKa around 50</p> Signup and view all the answers

    Which statement is true regarding the bond characteristic of alkanes?

    <p>They have strong σ bonds.</p> Signup and view all the answers

    What role do chlorine radicals play during the halogenation of alkanes?

    <p>They act as a chain carrier in propagation.</p> Signup and view all the answers

    During the halogenation process, what is the effect of absorbing light on alkane molecules?

    <p>Generates thousands of alkyl halides.</p> Signup and view all the answers

    Study Notes

    MPharm Programme - PHA111 Functional Group Chemistry 1

    • Lecturer: Dr. Stephanie Myers
    • Date: Dale 1.21
    • Email: [email protected]
    • Phone: 0191 5152760

    Learning Objectives

    • Appreciate the importance of functional group chemistry for pharmacy students
    • Define diverse mechanistic terms to deduce and explain reaction mechanisms
    • Identify nucleophiles, electrophiles, and determine leaving groups in organic molecules
    • Identify functional groups in drug molecules and understand their properties, focusing on alkanes in the lecture
    • Use accurate curly arrows to denote bond-making and breaking processes, focusing on alkane chemistry
    • Explain product distribution patterns based on radical stability via hyperconjugation and resonance stabilisation

    Functional Groups

    • Understanding functional group chemistry allows for analysis of drug properties like:
      • Chemical structure
      • Ionisation
      • Solubility (lipid vs. aqueous)
      • Absorption, Distribution, Metabolism, Excretion (ADME)

    Functional Groups (continued)

    • Understanding how receptor binding produces a therapeutic effect and design new medicines for specific purposes
    • Understanding how physiochemical properties affect analytical choices

    What is a Functional Group?

    • Most drugs are simple organic molecules composed of two parts:
      • A hydrocarbon part (usually unreactive)
      • A functional group (FG) where most reactions occur
    • Molecules with the same functional group typically have similar properties and characteristic reactivities.
      • Examples of functional groups in the slides include: primary amine, secondary amide, phenol, lactam (cyclic amide), carboxylic acid, and an example of a drug containing some of these functional groups is amoxicillin

    Chemical Similarity

    • Emergency!!! Extreme Bronchospasm in asthma sufferer!
    • The slides display several chemical structures related to the concept.

    What is a Functional Group? (continued)

    • Defining various types of hydrocarbons:
      • Alkanes (straight, branched, cyclic)
      • Alkenes (terminal, internal, cyclic)
      • Alkynes (terminal, internal)
      • Alcohols (primary, secondary, tertiary, phenol)

    What is a Functional Group? (continued)

    • Alkyl halides (primary, secondary, tertiary)
    • Amines (primary, secondary, tertiary, quaternary)
    • Amides (primary, secondary, tertiary)
    • Aldehydes and Ketones

    3D Representations

    • Sp3 hybridised carbon atoms have a tetrahedral shape.
    • Representations use wedged and hashed bonds.
      • Wedge bonds point towards the viewer
      • Hashed bonds point away from the viewer
    • Plain bonds are in the plane of the screen
    • Crucial for understanding chiral molecules and chiral centers (carbon atom with four different groups attached).

    Reactivity and Reaction Mechanisms

    • Mechanisms are detailed step-by-step descriptions of chemical processes.
    • They involve the movement of electrons as bonds are made or broken.
    • Reactions can be classified as ionic/polar (movement of two electrons in turn) or radical (movement of one electron in turn).

    Nucleophile

    • Defined as "nucleus-loving"
    • Electron-rich molecules, usually with a negative charge or lone pairs of electrons, with curly arrows starting at the electron rich center.
    • Double bonds can act as nucleophiles.

    Electrophile

    • Described as "electron-loving"
    • Electron-poor molecules, often with a positive charge or polarisable atoms, with curly arrows ending at the electron poor center
    • Polarisation by proximity can occur.

    Leaving Groups

    • Terminology for ions or neutral molecules displaced from a reactant during mechanistic sequences.
    • Normally a consequence of a nucleophile attacking an electrophile.
    • Good leaving groups form stable ions or neutral molecules.
    • Students are expected to practice writing mechanisms involving nucleophiles, electrophiles, and leaving groups.

    Bond Cleavage

    • Heterolysis: Both electrons in a bond go to one atom.
    • Homolysis: Each atom in a bond receives one electron.

    Curly Arrows - Polar Mechanisms

    • Double-headed arrows indicate movement of two electrons.
    • Arrow placement is crucial for determining reaction pathways.
    • These arrows visually represent the movement of electron pairs between electron-rich and electron-poor centers.

    Curly Arrows - Radical Mechanisms

    • Single-headed arrows represent the movement of one electron.
    • Two radicals form a bond by donating electrons to each other.
    • A bond breaks in a similar way, except each atom receives one electron.

    Transition States and Intermediates

    • Mechanisms might include predicted structures such as charged species or radicals.
    • Diagrams illustrating the change in energy during reactants -> products are helpful visuals of the reaction processes.
    • Energy difference between reactants and products is the standard free energy change ( $\Delta G^{\circ} $).
    • High energy peaks represent transition states (or activated complexes).
    • Energy minima between transition states indicate intermediates (structures in the pathway).

    Why Study Mechanisms?

    • Pharmacists need to understand how drugs are manufactured.
    • Drugs covalently bind to biological targets through chemical mechanisms.
    • Understanding metabolic processes helps predict drug stability.
    • Understanding degradation mechanisms can improve drug stability.

    Penicillins MOA

    • Amoxicillin: Example of a covalent inhibitor, reacting through electrons within an active enzyme site by forming esters.
    • Describes the reaction mechanism of Amoxicillin and relates it to the concept of covalent inhibitors.

    Hydrocarbon Compounds

    • Classification of hydrocarbons as aliphatic (linear, cyclic, saturated, unsaturated) or aromatic.
    • Alkanes: Definition focusing on structure (containing only single bonds, C-C and C-H bonds) and properties (very unreactive, low reactivity with ionic or polar substances).

    Alkanes: Physical Properties

    • Melting and boiling points increase with increasing chain length and molecular weight due to weaker London dispersion forces.

    Alkanes: Reactivity

    • Alkanes are generally unreactive.
    • Combustion reactions (reacting with oxygen to produce CO2, H2O and heat) and halogenation (reacting with halogens at high temperatures) are discussed.

    Alkanes: Halogenation

    • Radical mechanism for halogenation is outlined, including initiation, propagation, and termination steps

    Alkanes: Halogenation (continued)

    • Chlorine radical (Cl∙) is a chain carrier in propagation steps, leading to free-radical substitution for H with Cl.
    • Example reaction of monochlorination of methane

    Radical Stability

    • Factors determining the substituted product distribution include probability and radical stability.
    • Stability relates to the number of carbons bonded to the carbon with the unpaired electron (methyl, primary, secondary, tertiary).

    Radical Stability (continued)

    • More stable radicals form more stable products.
    • Benzyl and allyl radicals are unusually stable due to resonance.

    Hyperconjugation

    • Hyperconjugation is a stabilising interaction resulting from interaction of σ bonds (of C-H alkyl groups) with the unfilled p orbital.
    • Stabilises alkyl radicals by extending the electron system

    Resonance Contributors and Hybrids

    • Resonance contributors (e.g., unicorn and dragon) are different possible structures for a molecule connected by double-headed arrows.
    • Resonance hybrid (rhinoceros) is the overall representation of the molecule as a combination of contributors.

    Resonance Structures

    • Being able to draw resonance structures is crucial for drawing and understanding reaction mechanisms.
    • Resonance forms are not isomers or different compounds.
    • Resonance structures are represented using double-headed arrows.

    Resonance

    • Resonance describes delocalization of electrons and/or charges.
    • sp3 hybridised atoms cannot accept electrons during resonance.
    • Resonance structures only exist on paper; they represent different extreme possibilities of the locations of electrons).

    Resonance Structures (continued)

    • The same number of paired and unpaired electrons exist in each resonance form.
    • Atoms must be in the same plane, which requires overlap of p orbitals.
    • The most stable form of resonance makes the largest contribution to the overall structure.

    Resonance Stabilisation of Radicals

    • The relative stability of different radicals is explained with examples and diagrams.
    • Important resonance contributors of radicals like benzyl are represented and discussed.

    Oxidation - AutoOxidation

    • Oxidation (radical process) is a reaction that increases the number of bonds to oxygen and decreases the number of bonds to hydrogen.
    • Auto-oxidation leads to drug degradation.
    • Typical conditions that trigger autoxidation mechanisms include light, heat, and some metal ions, and these reactions are explained with diagrams and example structures.

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    Week 10 Functional Group Chemistry 1 PDF

    Description

    Explore the significance of functional groups in pharmacy through this quiz. Understand the roles of nucleophiles, radical stability, and drug design principles that are essential for predicting the properties of drug molecules. Test your knowledge of key organic chemistry concepts critical for pharmacy students.

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