Organic Chemistry II - Topic 1 Quiz (Chapter 9)
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Questions and Answers

What is the general formula for alkynes?

  • CnH2n+2
  • CnH2n-2 (correct)
  • CnH2n
  • CnHn

    • How many elements of unsaturation are present for each triple bond in an alkyne?

  • 4
  • 1
  • 3
  • 2 (correct)

    • Which type of hybridization is present in the carbon atoms of an alkyne triple bond?

  • dsp2
  • sp (correct)
  • sp3
  • sp2

    • Which of the following best describes the geometry of the alkyne triple bond?

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

    How should the carbon chain be numbered when naming an alkyne?

    <p>Start at the end closest to the triple bond</p> Signup and view all the answers

    In an alkyne, the two pi bonds are oriented in which way to each other?

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

    Which of the following reactions is specific to alkynes and not alkenes?

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

    Which statement is correct regarding cis-trans isomerism in alkynes?

    <p>The linear geometry of alkynes prevents cis-trans isomerism</p> Signup and view all the answers

    What is the minimum number of carbon atoms required for a stable cycloalkyne?

    <p>9</p> Signup and view all the answers

    If a molecule contains an alkene and an alkyne functional group, what is it generally called?

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

    When numbering a carbon chain with both an alkene and alkyne, which gets the lowest number?

    <p>The first unsaturation encountered, with alkene taking priority if numbering is equal.</p> Signup and view all the answers

    What priority is given in naming compounds with an alcohol, double, and triple bonds?

    <p>Alcohol &gt; double bond &gt; triple bond</p> Signup and view all the answers

    Which statement correctly describes the physical properties of alkynes?

    <p>Nonpolar, insoluble in water, and less dense than water.</p> Signup and view all the answers

    What type of hybrid orbitals are present in the carbon atoms of a triple bond?

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

    Why are terminal alkynes more acidic than other hydrocarbons?

    <p>They have a higher s-character in the sp hybrid orbital.</p> Signup and view all the answers

    Which base is strong enough to deprotonate a terminal alkyne quantitatively?

    <p>Sodium amide (NaNH2)</p> Signup and view all the answers

    Which of the following best describes the relationship between enol and keto forms?

    <p>They are structural isomers with different proton locations.</p> Signup and view all the answers

    Which of the following best describes the role of a strong base, such as potassium 1,3-diaminopropanide (KAPA), in the zipper reaction?

    <p>It deprotonates an internal alkyne, shifting the triple bond to the end of the chain.</p> Signup and view all the answers

    What is the product of an internal alkyne undergoing oxidation with a dilute, neutral solution of $KMnO_4$?

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

    In the reduction of an alkyne to an alkane using H2 and a catalyst, what is the correct number of hydrogen molecules that must be added across the triple bond?

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

    What is the product of a terminal alkyne when reacted with excess $KMnO_4$ in basic and warm conditions?

    <p>Two molecules of carboxylic acids</p> Signup and view all the answers

    What products are formed when an alkyne undergoes ozonolysis followed by hydrolysis?

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

    What type of stereochemistry is produced when an alkyne is reduced using Lindlar's catalyst?

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

    What is the primary function of the catalyst in the reaction where an alkyne is reduced by H2?

    <p>To adsorb hydrogen and the alkyne, facilitating the reaction.</p> Signup and view all the answers

    What is the major product when an alkyne is reacted with mercuric sulfate in aqueous sulfuric acid?

    <p>A ketone formed from the rearrangement of a vinyl alcohol</p> Signup and view all the answers

    What is the major product when 1 mole of $Br_2$ reacts with an alkyne?

    <p>Vinyl dihalide</p> Signup and view all the answers

    Which reagent combination is used to achieve anti-Markovnikov hydration of an alkyne?

    <p>Disiamylborane followed by an oxidizing agent</p> Signup and view all the answers

    What is produced when 2 moles of HBr are added to an alkyne?

    <p>Geminal dibromide</p> Signup and view all the answers

    What type of intermediate is formed when an electron is added to an alkyne in the reduction with sodium in ammonia?

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

    Which of the following reagents is used to convert an alkyne to a trans alkene?

    <p>Na in NH3</p> Signup and view all the answers

    How does the product of an alkyne oxidation with an equal molar amount of $KMnO_4$ in neutral conditions differ from the product using a warm, basic $KMnO_4$?

    <p>Neutral conditions yield diketones; warm, basic conditions yield carboxylic acids</p> Signup and view all the answers

    Which of the following statements is true about the addition of borane to a terminal alkyne?

    <p>Borane adds preferentially to the less substituted carbon</p> Signup and view all the answers

    Which type of compound is produced from the reaction of a terminal alkyne with $O_3$ followed by $H_2O$

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

    Based on the information provided, which of the following is true about alkynes compared to alkenes?

    <p>Alkynes reduce more readily than alkenes.</p> Signup and view all the answers

    What is the driving force for the tautomerization of an enol to a carbonyl compound?

    <p>Formation of a C=O bond</p> Signup and view all the answers

    If 2-butyne is reacted with $Br_2$, what would be the main organic product?

    <p>A tetrabromide alkane</p> Signup and view all the answers

    What is the nature of the intermediate formed during the hydration of an alkyne with mercuric sulfate?

    <p>A vinyl cation</p> Signup and view all the answers

    The reaction of an alkyne with $BH_3$ followed by oxidation will generate an enol which will tautomerize to what functional group?

    <p>An aldehyde</p> Signup and view all the answers

    Compared to alkenes, why do alkynes react slower with mercuric sulfate-catalyzed hydration?

    <p>The intermediate is a vinyl cation which is less stable than a secondary carbocation</p> Signup and view all the answers

    The use of disiamylborane in the hydroboration of alkynes is important to prevent which outcome?

    <p>Double addition of borane to triple bond</p> Signup and view all the answers

    What is the IUPAC name of the major product formed when 2-butyne undergoes bromination?

    <p>1,2-Dibromobutane</p> Signup and view all the answers

    Which of the following statements about the acidity of terminal alkynes is true?

    <p>Terminal alkynes can be deprotonated by strong bases.</p> Signup and view all the answers

    What is the expected product when an alkynyl halide is treated with a strong nucleophile?

    <p>Substitution to form a substituted alkyne</p> Signup and view all the answers

    Which intermediate is formed during the hydration reaction of an internal alkyne with mercuric sulfate?

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

    Which statement correctly describes the stability of cyclohexyne?

    <p>Cyclohexyne does not exist as a stable molecule.</p> Signup and view all the answers

    What explains why the conjugate base of 2-butyne is a weaker base?

    <p>It is stabilized by resonance.</p> Signup and view all the answers

    Which reagent pair would best complete the reaction of 2-butyne with bromine?

    <p>HgSO₄, H₂O, H₂SO₄</p> Signup and view all the answers

    How many curved arrows are needed for the reaction mechanism described in steps 1-4?

    <p>4 curved arrows</p> Signup and view all the answers

    Which of the following techniques would correctly match with the synthesis of 3-methyl-1-butene?

    <p>HBr, CH₃OOCH₃</p> Signup and view all the answers

    Which reagent is necessary for the synthesis of 1-bromopropane from the precursor steps?

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

    What product results when 2-butyne is treated with Na/NH₃?

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

    Which reagent would be used to complete the hydration of a compound after mercury treatment?

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

    What type of mixture is produced when an alkyne is reacted with bromine in an anti-addition manner?

    <p>A 1:1 mixture of two separate isomers</p> Signup and view all the answers

    How many curved arrows are needed to complete the isomerization mechanism of 1-butyne to 2-butyne?

    <p>12</p> Signup and view all the answers

    Based on the molecular formula C₁₀H₁₄, which of the following is the correct name of the unknown compound that underwent ozonolysis?

    <p>deca-4,6-diyne</p> Signup and view all the answers

    Which of the following syntheses is likely to fail due to unsatisfactory reaction pathways?

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

    Which bond corresponds to the largest wave number for stretching vibration in the IR spectrum?

    <p>C≡C</p> Signup and view all the answers

    Which driving force primarily facilitates the tautomerism from enol to carbonyl?

    <p>Making C=O bond</p> Signup and view all the answers

    In the provided mechanism, how many steps utilize the Rearrangement type of mechanism?

    <p>2</p> Signup and view all the answers

    What type of compound is generally produced from the reaction of a terminal alkyne with $O_3$ followed by $H_2O$?

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

    What occurs when a terminal alkyne undergoes hydroboration followed by oxidation?

    <p>Formation of an enol that tautomerizes to a carbonyl</p> Signup and view all the answers

    What is the IUPAC name for the molecule with the structure containing Br, OH, H₃C, and CH₃?

    <p>(S,Z)-8-bromonona-7-en-4-yn-2-ol</p> Signup and view all the answers

    Which statement correctly describes the bond lengths in alkynes?

    <p>Double bonds are shorter than triple bonds.</p> Signup and view all the answers

    What is the result of hydrating a terminal alkyne using mercuric sulfate in aqueous sulfuric acid?

    <p>Formation of a ketone.</p> Signup and view all the answers

    When performing hydroboration-oxidation on a terminal alkyne, what is the expected product?

    <p>An aldehyde.</p> Signup and view all the answers

    What type of catalyst is required to achieve syn-addition when reducing an alkyne to a cis-alkene?

    <p>Lindlar's catalyst</p> Signup and view all the answers

    Which reaction condition would typically lead to anti-Markovnikov hydration of an alkyne?

    <p>Using BH₃ followed by oxidation with H₂O₂.</p> Signup and view all the answers

    In ozonolysis of an alkyne followed by hydrolysis, what are the expected products?

    <p>Two carboxylic acids.</p> Signup and view all the answers

    Which reagent is commonly used to oxidize an internal alkyne to a diketone?

    <p>KMnO₄ under acidic conditions</p> Signup and view all the answers

    How many products are expected when a mixture of 1-octyne, 2-octyne, 3-octyne, and 4-octyne is treated with H₂ and PtO₂ in acetic acid?

    <p>2</p> Signup and view all the answers

    What describes the product when an alkyne is reduced to a trans alkene with sodium in ammonia?

    <p>A single diastereomer will be produced.</p> Signup and view all the answers

    Which of the following best describes the role of the enol intermediate during the hydration of an alkyne to produce a ketone?

    <p>It tautomerizes to form the final ketone product.</p> Signup and view all the answers

    Which intermediate forms during the tautomerization process of an alkyne hydration to yield a ketone?

    <p>An enol</p> Signup and view all the answers

    What is the expected result when an unknown compound with the molecular formula C₆H₁₀ undergoes IR, ¹H-NMR, and ¹³C-NMR characterization?

    <p>It could indicate an alkyne or unsaturated compound.</p> Signup and view all the answers

    Which of the following is true regarding sodium methoxide, sodium acetylide, sodium amide, and ammonia in terms of their acidity?

    <p>Ammonia is less basic than sodium amide.</p> Signup and view all the answers

    What kind of compound is produced when a terminal alkyne is oxidized with ozone followed by hydrolysis?

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

    Which option describes the acidity of acetylene, methane, ammonia, and methanol?

    <p>Methanol is the third strongest acid.</p> Signup and view all the answers

    What role does sodium play when alkynes are treated with sodium metal in liquid ammonia?

    <p>Reducing agent.</p> Signup and view all the answers

    Which product is formed when a terminal alkyne reacts with sodium acetylide?

    <p>Alkynyl ether.</p> Signup and view all the answers

    In predicting the products of alkynes undergoing electrophilic addition, what is a common misconception regarding the markovnikov regioselectivity?

    <p>The reaction will always favor the formation of the most stable carbocation.</p> Signup and view all the answers

    Why is the conjugate base of 2-butyne considered a weaker base due to resonance?

    <p>It distributes negative charge over more electronegative atoms.</p> Signup and view all the answers

    Which reagent is typically used alongside dry sodium acetate for deprotonation of terminal alkynes?

    <p>Sodium acetylide.</p> Signup and view all the answers

    What is the primary function of the Lindlar catalyst during alkyne reactions?

    <p>To selectively hydrogenate the alkyne to cis-alkene.</p> Signup and view all the answers

    What type of reaction mechanism is commonly seen when sodium metal is used in the reaction of alkynes with liquid ammonia?

    <p>Bond formation through reduction.</p> Signup and view all the answers

    What is the likely outcome when excess HBr is added to an alkyne?

    <p>Formation of a vicinal dibromide.</p> Signup and view all the answers

    Study Notes

    Course Information

    • Course name: Chemistry 232, Organic Chemistry II
    • Course assignments include:
      • Topic 1 Quiz (Chapter 9): Week 3, 4%
      • Exam I (Chapters 10, 11, 14): Week 6, 15%
      • Exam II (Chapters 15, 16, 17): Week 9, 20%
      • Exam III (Chapters 18, 19): Week 12, 10%
      • Exam IV (Chapters 20, 21, 22): Week 15, 15%
      • ACS Exam: Week 15, 10%
      • Homework (HW): 11%, 50-100 questions per chapter (see calendar)
      • Participation: 15%, complete Participation WS Due Monday
      • Total Points: 100 (1000)
    • Exams: Closed-book, closed-note; a reaction sheet is provided.
    • Homework Guidelines:
      • 50-100 questions per chapter, based on participation, review packet, or old exams.
      • Indicate the source of questions.
      • Include a 1-2 sentence rationale for answers.
      • Average about 10 questions per day.
    • Participation Policy:
      • Complete Participation WS Due Monday
      • Participation Questions are in Explore Review
      • Testmoz link will be posted if needed.
      • Do not post on Chegg.
    • HW Grading:
      • 5 points for completion (100 problems)
      • 5 points for accuracy and format

    Chapter 9 - Alkynes

    • Alkynes contain a triple bond.
    • General formula is CnH2n-2.
    • Two elements of unsaturation for each triple bond.
    • Reactions similar to alkenes (addition and oxidation) and alkyne-specific reactions (substitution).
    • Structure
      • Triple Bond
      • Linear
      • sp hybridization
      • no cis-trans possibilities
      • 2 pi bonds perpendicular to each other. More reactive than alkenes. Useful intermediates in organic synthesis.
    • Physical Properties
      • Nonpolar, insoluble in water.
      • Soluble in most organic solvents.
      • Boiling points are similar to alkanes of the same size.
      • Less dense than water.
      • Up to four carbons, gas at room temperature.
    • IUPAC Nomenclature
    • Find the longest chain containing the triple bond.
    • Change -ane ending to -yne.
    • Number the chain starting at the end closest to the triple bond.
    • Give branches a number to locate their position.
    • If more than one triple bond use di, tri, tetra, etc.
    • If a molecule also has an alcohol, the alcohol has higher priority than double and triple bonds (considered branches).
    • Common Names: alkylacetylene or dialkylacetylene (e.g., methylacetylene, phenylacetylene, cyclohexylmethylacetylene).

    Multiple Functional Groups

    • If other functional group is alkene → enyne
    • Number such that the first unsaturated bond gets the lowest number.
    • If numbering is equal start with alkene (alphabetical)

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    Description

    Prepare for your Topic 1 Quiz in Organic Chemistry II, covering Chapter 9. This quiz will test your understanding of crucial concepts and reactions that are fundamental to organic chemistry. Ensure you review the material thoroughly to excel in this assessment.

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