Describe and explain the one-step SN2 mechanism of primary halogenoalkanes (backside attack through a transition state, second order rate) and the two-step SN1 mechanism of tertiary halogenoalkanes via a carbocation (first order), drawing both with curly arrows.
Tę umiejętność sprawdza 29 zadań wzorowanych na arkuszach IB z lat 2022–2026.
Pentane reacts with bromine, Br2, to form 2-bromopentane. (i) Explain, using equations, the initiation step and two propagation steps for this reaction. (ii) 2-Bromopentane reacts with aqueous sodium hydroxide, NaOH(aq), to form pentan-2-ol,…
1-Bromobutane, CH3CH2CH2CH2Br, is used as a solvent and as a building block for other organic compounds. (i) Predict the organic compound produced from 1-bromobutane and hydroxide ions. (ii) Deduce the type of reaction in (i) and give a reason for your…
Reactions of halogenoalkanes with hydroxide ions are an example of nucleophilic substitution. (i) Sketch the mechanism for the reaction of 1-chloropropane with aqueous potassium hydroxide. Use curly arrows to show the movement of electrons. (ii) State the name…
Which of these reactions are nucleophilic substitutions? I. OH− + CH3CH2CH2Cl → CH3CH=CH2 + H2O + Cl− II. I− + CH3CH2Br → CH3CH2I + Br− III. CH3O− + CH3CH2Cl → CH3CH2OCH3 + Cl− A. I and II only B. I and III only C. II and III only D. I,…
Cyanide ions react with bromoethane, CH3CH2Br. (i) Draw the full structural formula of the organic product of this reaction. (ii) Predict which mechanism, SN1 or SN2, operates in this reaction, and give a reason for your choice.…
The rate of the reaction between compound Y and aqueous sodium hydroxide depends on the concentrations of both reactants. (i) Explain the mechanism of this reaction, using curly arrows to show the movement of electron pairs. (ii) Explain why…
When 1-bromopropane is warmed with aqueous sodium hydroxide, NaOH(aq), propan-1-ol is formed. (i) State the name given to this reaction's mechanism. (ii) Draw the structure of the transition state that occurs during this mechanism. (iii) Deduce the rate…
(i) Concentrated sulfuric acid, H2SO4, is used as the catalyst in the manufacture of propyl ethanoate. Explain how the catalyst affects the reaction. (ii) The conversion of propane into 1-bromopropane,…
Iodoethane can react with aqueous hydroxide ions to produce ethanol. CH3CH2I(l) + OH−(aq) → CH3CH2OH(aq) + I−(aq) (i) State what type of reaction this is. (ii) Using curly arrows to show the movement of electron pairs, sketch the mechanism of this…
Which statement is correct about an SN1 mechanism? A. The rate of reaction depends on the concentrations of both the halogenoalkane and the nucleophile. B. The rate-determining step forms a carbocation intermediate from a single molecule. C. The…
1-Bromobutane reacts with aqueous sodium hydroxide to form butan-1-ol. Which statement about this reaction is correct? A. A carbocation intermediate is formed. B. The hydroxide ion attacks the bromine atom. C. The C−Br bond breaks before the nucleophile…
Butan-1-ol can be produced from 1-bromobutane. (i) Identify a nucleophile that would convert 1-bromobutane into butan-1-ol. (ii) Using curly arrows, sketch the mechanism for the reaction of 1-bromobutane with the nucleophile you identified in (i).
1-Bromopropane reacts with aqueous sodium hydroxide to give propan-1-ol. (i) Identify the type of mechanism for this reaction. (ii) Explain the mechanism, using curly arrows to show the movement of electron pairs.
Which reaction would be the fastest under the same conditions? A. CH3CH2CH(Cl)CH3 + OH− B. CH3CH2C(CH3)2Cl + OH− C. CH3CH2CH(I)CH3 + OH− D. CH3CH2C(CH3)2I + OH−
1-Bromopropane can be converted into propan-1-ol. Identify a suitable reagent and the conditions needed for this conversion.
1-Bromobutane reacts with warm aqueous sodium hydroxide to form butan-1-ol. CH3CH2CH2CH2Br + OH− → CH3CH2CH2CH2OH + Br− Which row gives the mechanism and the rate expression of this reaction? A. SN1; rate = k[C4H9Br] B.…
Identify the reagents for each step.
(i) Identify the type of reaction that takes place in step 1. (ii) Sketch the mechanism of the reaction in step 1, using curly arrows to show the movement of electron pairs. (iii) Identify the products formed from the reaction of propan-1-ol and propanoic acid…
What is the correct order of reaction types in the following sequence? A. I: addition; II: substitution; III: oxidation B. I: substitution; II: addition; III: oxidation C. I: addition; II:…
Which of the following pairs of reactants could form the carbocation intermediate shown? I. (CH3)2C=CHCH3 and HBr II. CH3CH2CH(CH3)CH2Br and H2O III. CH3CH2C(CH3)2Br and H2O A. I and II only B. I and III only C. II and…
Which of these halogenoalkanes reacts fastest with aqueous hydroxide ions by an SN1 mechanism? A. CH3CH2CH2CH2Br B. CH3CH2CH2CH2I C. (CH3)3CBr D. (CH3)3CI
Bromoethane can be converted into ethanol: CH3CH2Br + HO− → CH3CH2OH + Br− (i) Identify the type of reaction. (ii) Outline what must be true of a collision between reacting particles for a reaction to occur. (iii) Explain the mechanism of this…
(i) Explain the mechanism of the reaction between 1-chloropropane, CH3CH2CH2Cl, and aqueous potassium hydroxide, KOH(aq), using curly arrows to represent the movement of electron pairs. (ii) Deduce the splitting pattern, in the NMR…
The table shows initial rate data for the hydrolysis of a tertiary halogenoalkane, RBr, with aqueous sodium hydroxide at constant temperature. Which statements are correct? I. The reaction is first order with respect to hydroxide ions. II. The reaction is…
Which energy profile diagram represents an exothermic SN2 reaction of a primary halogenoalkane with a nucleophile? A. Diagram A B. Diagram B C. Diagram C D. Diagram D
Which sequence of reagents converts but-1-ene into butanone? Each reagent is added to the product of the previous reaction. A. HBr, then NaOH(aq), then acidified K2Cr2O7(aq) B. HBr, then acidified K2Cr2O7(aq), then…
This reaction could proceed through either an SN1 or an SN2 mechanism, depending on the reaction conditions. Sketch a graph of the rate against the nucleophile concentration, [OH−], for each of the mechanisms on the axes…
Starting from a single enantiomer of 2-bromopentane, only one enantiomer of the alcohol product, pentan-2-ol, is obtained. Suggest, with a reason, whether the reaction follows an SN1 or an SN2 mechanism.
2-Bromopentane also reacts with cyanide ions, CN−, by the same mechanism as the one identified in (b). Explain this mechanism using curly arrows to represent the movement of electron pairs.
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