Organic Chemistry Mechanisms and Reactions
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Questions and Answers

What type of mechanism is involved in the formation of a racemate as described?

  • Nucleophilic substitution
  • SN2 mechanism
  • Electrophilic addition
  • SN1 mechanism (correct)

    • A racemate formed in SN1 mechanism exhibits optical activity.

    False

    What is produced when a haloalkane reacts via an SN1 mechanism?

    A racemate

    In the SN1 mechanism, the first step involves the formation of a __________ intermediate.

    <p>planar carbocation</p> Signup and view all the answers

    Match the following descriptions with the correct mechanisms:

    <p>SN1 = Leads to optical inactivity due to racemate formation SN2 = Inverse stereochemistry at the reaction site</p> Signup and view all the answers

    What is formed when aldehydes react with Fehling’s Solution?

    <p>Carboxylic acids</p> Signup and view all the answers

    Ketones react with Tollen’s reagent to produce a silver mirror.

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

    What type of alcohol do aldehydes reduce to when treated with reducing agents such as NaBH4?

    <p>Primary alcohols</p> Signup and view all the answers

    When ketones are treated with reducing agents like LiAlH4, they are reduced to __________.

    <p>secondary alcohols</p> Signup and view all the answers

    Match the following reagents with their corresponding reaction outcomes:

    <p>Fehling’s Solution = Oxidation of aldehydes to carboxylic acids Tollen’s reagent = Formation of a silver mirror NaBH4 = Reduction of carbonyls to alcohols LiAlH4 = Reduction of aldehydes to primary alcohols</p> Signup and view all the answers

    What prefix is used for compounds that contain a ketone group in addition to a carboxylic acid?

    <p>oxo-</p> Signup and view all the answers

    A compound with carboxylic acid groups on both ends of the chain is called a mono-dioic acid.

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

    What is the name for the compound: C2H2O4?

    <p>Ethanedioic acid</p> Signup and view all the answers

    Esters are named using a bit ending in –yl from the __________ and –anoate from the __________.

    <p>alcohol, carboxylic acid</p> Signup and view all the answers

    Match the following compound names with their corresponding groups:

    <p>Ethanedioic acid = Dioic acid 2-oxopropanoic acid = Ketone and carboxylic acid Butanenitrile = Nitrile 2-hydroxy-2-methylpropanenitrile = Nitrile with additional hydroxyl and methyl groups</p> Signup and view all the answers

    Which naming convention is correct for a nitrile compound?

    <p>It ends in –nitrile, counting the C of the CN as the last carbon.</p> Signup and view all the answers

    The stem of the name for butanenitrile includes 'butan' and does not end with 'nitrile'.

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

    What is the main feature of ester nomenclature?

    <p>Esters are named using a part from the alcohol and a part from the carboxylic acid.</p> Signup and view all the answers

    What phenomenon causes signals in high resolution H NMR to be split into further lines?

    <p>Spin-Spin coupling</p> Signup and view all the answers

    Nuclei in identical chemical environments will show spin-spin coupling in H NMR.

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

    What is the effect of inequivalent hydrogen atoms on neighboring carbon atoms in H NMR spectroscopy?

    <p>It causes spin-spin coupling and leads to the splitting of signals.</p> Signup and view all the answers

    In high resolution H NMR, individual signals are affected by spin-spin coupling among ________ on neighboring carbon atoms.

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

    Match the following concepts related to H NMR with their descriptions:

    <p>Spin-Spin coupling = Splitting of NMR signals due to neighboring hydrogens Nuclei in identical environments = Do not exhibit spin-spin coupling Chemical shift = Variation in resonance frequency due to the electronic environment High resolution H NMR = Data collection that provides detailed signal splitting</p> Signup and view all the answers

    Which solvent is a good choice for non-polar organic molecules?

    <p>CCl4</p> Signup and view all the answers

    CDCl3 is a non-polar solvent suitable for polar organic molecules.

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

    What compound is added to a sample to calibrate the NMR spectrum?

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

    The measure of how far the frequency of the proton signal has shifted from TMS is known as the chemical ______.

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

    Match the following solvents with their properties:

    <p>CCl4 = Good for non-polar organic molecules CDCl3 = Good for polar organic molecules TMS = Inert and used for calibration H2O = Polar solvent for many reactions</p> Signup and view all the answers

    Which of the following is a reason TMS is used for calibration?

    <p>It provides a strong signal with a single peak</p> Signup and view all the answers

    The δ scale is a measure in parts per thousand (ppt).

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

    What does a greater shift in δ indicate about nearby atoms or groups?

    <p>More electronegative groups give a greater shift.</p> Signup and view all the answers

    What does the peak with the largest m/z value in a mass spectrum represent?

    <p>The parent ion or molecular ion</p> Signup and view all the answers

    The molecular ion is formed when an organic molecule loses an electron.

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

    What is the relationship between the charge of the ion and the mass/charge ratio in mass spectrometry?

    <p>The mass/charge ratio equals the molecular weight when the charge is +1.</p> Signup and view all the answers

    Fragmentation occurs due to the breaking of __________ bonds.

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

    Match the following types of ions with their characteristics:

    <p>Molecular ion = Parent ion with largest m/z Fragment ion = Produced from the molecular ion Carbocation = Relatively stable positive ion Free radical = Species with an unpaired electron</p> Signup and view all the answers

    Which of the following statements is true regarding the intensity of peaks in a mass spectrum?

    <p>The more stable the ion, the greater the peak intensity.</p> Signup and view all the answers

    Free radicals are formed directly from fragment ions.

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

    The molecular ion for butane, C4H10, is shown as [__________]+.

    <p>C4H10</p> Signup and view all the answers

    Study Notes

    Carbonyls, Carboxylic Acids and Chirality

    • Homologous series: A series of organic compounds with a similar structure, differing only by the addition of a -CH₂- group.
    • Alkenes: Hydrocarbons with carbon-carbon double bonds. Suffix -ene, example ethene.
    • Alcohols: Organic compounds containing a hydroxyl (-OH) group. Suffix -ol, example propan-1-ol.
    • Halogenoalkanes: Organic compounds containing a halogen atom (Cl, Br, I). Prefix chloro, for example 1-chloropropane.
    • Aldehydes: Carbonyls with the carbonyl group at the end of the carbon chain. Suffix -al, example ethanal.
    • Ketones: Carbonyls with the carbonyl group in the middle of the carbon chain. Suffix -one, example propanone.
    • Carboxylic acids: Organic compounds containing a carboxyl (-COOH) group. Suffix -oic acid, example ethanoic acid.
    • Nitriles: Contain a cyano group (-C≡N). Suffix -nitrile, example propanenitrile.
    • Amines: Contain an amino group (-NH₂). Suffix -amine, example propylamine.
    • Esters: Formed from a carboxylic acid and an alcohol. Have an -oate suffix, example methyl ethanoate.
    • Acyl chlorides: Formed from carboxylic acids and chlorine. Suffix -oyl chloride, example ethanoyl chloride.
    • Amides: Contain a carbonyl group and an amino group. Suffix -amide, example ethanamide.

    Chirality

    • Asymmetric carbon: A carbon atom bonded to four different groups.
    • Enantiomers: Non-superimposable mirror images of each other.
    • Racemic mixture: A 50/50 mixture of enantiomers. Neither rotate plane-polarized light.

    Reactions of Carbonyls

    • Oxidation of aldehydes: Aldehydes can be oxidized to carboxylic acids using potassium dichromate (VI) solution and dilute sulfuric acid. Aldehydes are oxidized, but ketones aren't.
    • Fehling's solution: A test solution used to identify the presence of aldehydes (blue to red precipitate).
    • Tollen's reagent: A test to show if an aldehyde is present (silver precipitate).
    • Reduction of carbonyls: Reducing agents (LiAlH₄) transform aldehydes to primary alcohols and ketones to secondary alcohols.
    • Addition of hydrogen cyanide to Carbonyls: Forms hydroxynitriles when carbonyls react with HCN and KCN.

    Carboxylic Acids

    • Acidity: Carboxylic acids are weak acids, slightly dissociating in water and capable of releasing CO₂ from carbonates.
    • Delocalisation: The pi-electron cloud involved in C-O bond delocalization stabilizes carboxylates, making them capable of forming salts.

    Esterification

    • Mechanism: Carboxylic acids and alcohols react in the presence of a strong acid catalyst to form esters and water.
    • Uses: Esters commonly used as scents and flavors.

    Acyl Chlorides

    • Reactivity: Acyl chlorides are more reactive than carboxylic acids in substitution reactions.
    • Reactions with water: Acyl chlorides undergo reactions with water to form carboxylic acids and hydrochloric acid.
    • Reactions with alcohol: Acyl chlorides form esters when reacted with alcohols.
    • Reactions with ammonia: Acyl chlorides form primary amides when reacted with ammonia.
    • Reactions with primary amines: Acyl chlorides form secondary amides when reacted with primary amines.

    Polyesters

    • Condensation polymer: Formed by the combination of monomers with the release of a small molecule such as water.
    • Properties: Polyesters often used for clothing and other applications.

    Spectroscopy and Chromatography

    • NMR Spectroscopy: Determines the number and arrangement of hydrogen atoms in a molecule.
    • Mass spectrometry: Breaks apart molecules to determine their mass-to-charge ratio (m/z).
    • TLC (Thin-Layer Chromatography): Separates components in a mixture based on their relative solubility in a mobile phase and a relatively stationary phase.

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    Description

    Test your knowledge on various organic chemistry mechanisms such as SN1 and the reactions involving aldehydes and ketones. This quiz covers important concepts like optical activity in racemates and the outcomes of different chemical reagents. Challenge yourself with matching descriptions and identifying reaction products.

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