Reactions of the Functional Groups — practice questions

State the reagent and conditions needed to convert (a) 1-bromobutane into butan-1-ol, and (b) butan-1-ol into but-1-ene.

Describe a two-step route to convert propan-2-ol into propanone, then into propan-2-ol again. Give the reagents and conditions for each step and explain why the second step is called a reduction.

Devise a reaction scheme to convert 1-bromopropane into propyl propanoate. For each step give the reagents, the conditions and the structural formula of the organic product. Justify why your scheme requires the starting material to be used in two separate portions.

Write equations for the reaction of 1-chloropropane with (a) NaOH(aq) and (b) KOH in alcohol, and name the organic product in each case.

Explain why 1-bromobutane gives a different product with KOH(aq) than with KOH dissolved in ethanol, and identify both products.

A student reacts 2-bromo-2-methylpropane, (CH₃)₃CBr, with concentrated ammonia in a sealed tube and obtains a poor yield of the expected amine, along with a substantial amount of an alkene. Explain the formation of the alkene, and evaluate whether increasing the concentration of ammonia would improve the yield of the amine. Compare this outcome with what you would expect from 1-bromobutane.

Write equations for the reaction of propan-1-ol with (a) HBr and (b) concentrated H₂SO₄ with heating, and name the organic product in each case.

Explain why thionyl chloride, SOCl₂, is often preferred to concentrated HCl for converting an alcohol into a chloroalkane.

Concentrated sulfuric acid is used both to dehydrate an alcohol to an alkene and as the catalyst in esterification. Explain how the same reagent can play these two different roles, and justify how a chemist would set up each reaction to obtain the intended product rather than the other one.

2-bromobutane is heated with KOH dissolved in ethanol. Name the major and the minor organic products.

Pentan-2-ol is heated with concentrated sulfuric acid. Draw the two organic products, identify which is the major product, and explain your reasoning.

A student eliminates HBr from an unknown bromoalkane of formula C₅H₁₁Br using KOH in ethanol, and obtains only a single alkene. A second student uses a different isomer of C₅H₁₁Br and obtains two alkenes. Identify a bromoalkane consistent with each result, justify your choices, and explain what this shows about when the major/minor rule applies.

Describe the test for a carbon–carbon double bond, stating the reagent and the observation, and write the equation for the reaction of but-2-ene with this reagent.

An alkene of formula C₄H₈ reacts with bromine water to give 1,2-dibromobutane. Identify the alkene and explain how the structure of the product allowed you to deduce it.

A student heats an unknown bromoalkane of formula C₄H₉Br with KOH in ethanol and obtains a mixture of two alkenes. Treating the mixture with bromine water gives two dibromides: 1,2-dibromobutane and 2,3-dibromobutane. Identify the original bromoalkane, justify your identification, and state which alkene was the major product with your reasoning.

State the product formed when each of propan-1-ol, propan-2-ol and 2-methylpropan-2-ol is heated under reflux with excess acidified dichromate, and give the observation in each case.

Explain why a primary alcohol can be oxidised to either an aldehyde or a carboxylic acid, and describe how the conditions are chosen to obtain the aldehyde.

A student oxidises butan-1-ol with acidified dichromate and collects a distillate. Testing the distillate, they find it gives a silver mirror with Tollens' reagent but also fizzes with sodium carbonate solution. Explain what these two observations together reveal about the distillate, evaluate the student's technique, and describe how the procedure could be improved.

Describe a test that distinguishes propanal from propanone, giving the reagent and the observation for each compound.

Explain why Tollens' reagent reacts with an aldehyde but not with a ketone or with a primary alcohol.

A compound Z of formula C₅H₁₀O gives no reaction with Tollens' reagent, but is reduced by NaBH₄ to a product that exists as enantiomers. Deduce a possible structure for Z, justify it fully, and explain why the Tollens' result alone would not have been sufficient to reach your answer.

Write equations for the reaction of propanoyl chloride with (a) water, (b) ethanol and (c) ammonia, and name the organic product in each case.

Describe a chemical test that distinguishes butanoic acid from butanoyl chloride, and explain why the test works.

A student is given a mixture of hexanoic acid, hexan-1-ol and hexyl hexanoate, all with six-carbon chains and all insoluble in water. Devise a scheme to separate all three, justifying each step, and explain why their similar chain lengths make a physical separation unattractive.

Write an equation for the reaction of ethanoyl chloride, CH₃COCl, with methylamine, CH₃NH₂, and state the type of reaction. Also write the equation for the reaction of ethylamine with hydrochloric acid.

Explain why propan-1-amine turns damp red litmus paper blue but propanamide does not, even though both contain an –NH₂ group.

A student wishes to prepare N-ethylpropanamide, CH₃CH₂CONHCH₂CH₃, starting from propan-1-ol and bromoethane as the only organic starting materials. Devise a full scheme with reagents, conditions and structures, and justify why the amide cannot be made by simply heating propanoic acid with ethylamine.

Give a chemical test, with observations, to distinguish ethanoic acid from ethanol.

Describe how you could distinguish between propan-1-ol, propanal and propanone using chemical tests. Give the reagents and all observations.

A single unknown liquid gives the following results: it decolourises bromine water, it fizzes with sodium carbonate solution, it gives no silver mirror with Tollens' reagent, and it has the molecular formula C₄H₆O₂. Deduce a structure for the unknown, justify each deduction, and explain why the negative Tollens' result was necessary rather than merely confirmatory.