Untitled Flashcards Set

What is the significance of Grignard reagents in organic synthesis?
A. They act as strong electrophiles.
B. They are used to form new carbon–carbon bonds.
C. They serve primarily as oxidizing agents.
D. They catalyze esterification reactions.

What role does magnesium play in the formation of Grignard reagents?
A. It acts as a Lewis acid to accept electrons from the alkyl halide.
B. It inserts into the carbon–halogen bond to form an organomagnesium intermediate.
C. It serves as an inert catalyst in the reaction.
D. It is reduced to form elemental magnesium.

What function does diethyl ether serve in the Grignard reaction setup?
A. It oxidizes the magnesium metal.
B. It acts as a solvent that coordinates with magnesium to stabilize the Grignard reagent.
C. It serves as a phase transfer catalyst.
D. It prevents moisture by reacting with water.

How can you differentiate between oxidation and reduction reactions?
A. Oxidation involves the gain of electrons, while reduction involves the loss of electrons.
B. Oxidation involves the loss of electrons, while reduction involves the gain of electrons.
C. Both oxidation and reduction involve the gain of oxygen atoms.
D. There is no difference; they are two names for the same process.

Which pair correctly identifies the oxidizing and reducing agents used in the labs?
A. Potassium permanganate (KMnO₄) for oxidation and lithium aluminum hydride (LiAlH₄) for reduction.
B. Chromic acid (H₂CrO₄) for oxidation and lithium aluminum hydride (LiAlH₄) for reduction.
C. Sodium hypochlorite (NaOCl) for oxidation and sodium borohydride (NaBH₄) for reduction.
D. Sodium hypochlorite (NaOCl) for oxidation and lithium aluminum hydride (LiAlH₄) for reduction.

How is the theoretical yield and percent yield of a reaction calculated?
A. The theoretical yield is determined by stoichiometric calculations from the limiting reagent, and percent yield is (actual yield/theoretical yield) × 100.
B. The theoretical yield is the experimentally measured product mass, and percent yield is the difference between theoretical and actual yield.
C. Theoretical yield is determined by the product’s melting point, and percent yield is calculated from volume measurements.
D. Percent yield is always assumed to be 100% under ideal conditions.

Which reducing reagent used in Lab 2 is considered stronger?
A. Sodium borohydride (NaBH₄)
B. Lithium aluminum hydride (LiAlH₄)
C. Sodium hypochlorite (NaOCl)
D. Potassium permanganate (KMnO₄)

Identify the oxidizing agent used in Lab 3 (provide both name and chemical formula).
A. Potassium permanganate, KMnO₄
B. Chromic acid, H₂CrO₄
C. Sodium hypochlorite, NaOCl
D. Hydrogen peroxide, H₂O₂

How is the theoretical yield of a product determined in an oxidation reaction?
A. By measuring the melting point of the product.
B. By calculating stoichiometry based on the limiting reagent.
C. By comparing the product’s color to a standard.
D. By the duration of the reaction.

What role does glacial acetic acid play in the oxidation reaction in Lab 3?
A. It acts solely as a solvent.
B. It functions as an acid catalyst that helps activate the oxidizing agent.
C. It neutralizes the base present in the reaction.
D. It serves as the oxidizing agent.

Why is anhydrous sodium sulfate used during the workup of the oxidation reaction?
A. To dissolve the product completely.
B. To remove water from the organic layer by drying it.
C. To neutralize any acidic impurities.
D. To catalyze the reaction further.

Which statement best defines kinetic versus thermodynamic products?
A. Kinetic products form faster but are less stable, while thermodynamic products form slower but are more stable.
B. Kinetic products are more stable than thermodynamic products.
C. Both types of products form at the same rate and have similar stabilities.
D. Kinetic products require high temperature, whereas thermodynamic products form only at low temperature.

How does reaction temperature influence kinetic and thermodynamic control?
A. Low temperatures favor thermodynamic control, while high temperatures favor kinetic control.
B. Low temperatures favor kinetic control, while high temperatures allow the system to reach equilibrium favoring thermodynamic control.
C. Temperature has no impact on whether kinetic or thermodynamic products form.
D. Both controls are equally favored at high temperature.

What effect does water have on the melting points of semicarbazones as observed in Lab 4?
A. Water increases the melting point by enhancing hydrogen bonding.
B. Water decreases the melting point due to solvation effects and impurity interference.
C. Water has no observable effect on the melting point.
D. Water causes semicarbazones to decompose, making melting point determination impossible.

How does reaction time affect the predominance of kinetic versus thermodynamic products?
A. Shorter reaction times favor thermodynamic products.
B. Longer reaction times favor kinetic products exclusively.
C. Shorter reaction times favor kinetic products, while extended reaction times allow equilibrium to form more thermodynamic products.
D. Reaction time does not influence product distribution.

What type of reaction is the Diels–Alder reaction, and which reactants does it involve?
A. A nucleophilic substitution reaction between a halide and a Grignard reagent.
B. A cycloaddition reaction between a conjugated diene (1,3-diene) and a dienophile (substituted alkene).
C. A radical polymerization process involving free radicals.
D. A condensation reaction between an aldehyde and an amine.

Which statement best describes the stereochemical outcome of the Diels–Alder reaction?
A. The reaction produces a racemic mixture with no selectivity.
B. Both endo and exo products are formed, with the endo product typically favored due to secondary orbital interactions.
C. The reaction exclusively produces the exo product.
D. The reaction leads to inversion of configuration at all stereocenters.

Why is the Diels–Alder reaction classified as a syn addition reaction?
A. Because bonds are formed on opposite faces of the reactant molecule.
B. Because bonds are formed simultaneously on the same face of the reactant molecule.
C. Because it proceeds via a free radical mechanism.
D. Because it occurs in two separate steps.

Comparing the endo and exo products in the Diels–Alder reaction, which product is typically favored and why?
A. The exo product is favored due to minimal steric hindrance.
B. The endo product is favored because of secondary orbital interactions and a lower activation energy.
C. Both products are produced in equal amounts under all conditions.
D. The endo product is less stable and therefore not favored.

How does the concerted cycloaddition mechanism of the Diels–Alder reaction contribute to its selectivity?
A. It allows the reaction to proceed via multiple intermediates that randomize stereochemistry.
B. It ensures that all new bonds are formed simultaneously, preserving the relative orientations of substituents.
C. It involves radical intermediates that determine regioselectivity.
D. It relies on an external catalyst to dictate the stereochemical outcome.

Why is it critical to cool the monomer collection receiver in an ice-water bath during the Diels–Alder experiment?
A. To increase the rate of distillation.
B. To prevent thermal decomposition of the monomer and avoid condensation of moisture.
C. To immediately initiate the cycloaddition reaction.
D. To promote polymerization of the monomer.

How does adding petroleum ether facilitate the isolation of the cycloadduct in the Diels–Alder experiment?
A. It completely dissolves the product for easy handling.
B. It lowers the solubility of the cycloadduct, causing it to precipitate out of solution.
C. It reacts with the cycloadduct to form a separable complex.
D. It functions as a catalyst for crystallization.

In the oxidation of cyclododecanol experiment, what roles do glacial acetic acid and acetone play?
A. They act as solvents that help dissolve the reactants and stabilize the reaction mixture.
B. They both function as oxidizing agents.
C. They serve as phase transfer catalysts.
D. They are inert diluents with no specific role.

Why is starch/iodide paper used to monitor the progress of the oxidation of cyclododecanol, and what does a blue/black color change indicate?
A. It detects unreacted cyclododecanol in the mixture.
B. It indicates the presence of oxidizing agents (or iodine generated in situ), signifying that the oxidation reaction is complete.
C. It measures the pH of the reaction solution.
D. It confirms the absence of moisture in the reaction.

What key safety precautions must be taken when working with methanolic sodium borohydride during the reduction of fluorenone?
A. Wear gloves and eye protection, and handle the reagent in a well-ventilated area to avoid skin contact and hydrogen gas buildup.
B. No special safety measures are needed because the reagent is non-reactive.
C. Only work under high-pressure conditions to prevent solvent evaporation.
D. Expose the reagent to air deliberately to keep it dry.