Organic synthesis

A sequence of reactions beginning with 1-bromobutane is shown.

Feb/March 2017

Compound X can be changed into compound Y in one step. What might X be?

Feb/March 2018

Alcohols, aldehydes and nitriles can each be changed into carboxylic acids. Which descriptions of how they are converted into carboxylic acids are correct?

Feb/March 2018

Glycerol, $\text{CH}_2(\text{OH})\text{CH(OH)}\text{CH}_2\text{OH}$, is used extensively in food manufacture and in pharmaceuticals. A sequence of reactions beginning with glycerol is shown.

Feb/March 2020

Compounds $J$ and $K$ are present in plant oils.

Feb/March 2022

Which reagents and conditions would lead to the production of butanenitrile, $\text{CH}_3\text{CH}_2\text{CH}_2\text{CN}$?

Feb/March 2023

Citric acid can be changed into tricarballylic acid in two steps. A compound intermediate, Q, is produced. Which reagents are required for each step?

Feb/March 2023

A series of reactions occurs, and the main product is compound Z. propanoic acid $\xrightarrow{\text{LiAlH}_4}$ compound X $\xrightarrow{\text{concentrated } \text{H}_2\text{SO}_4}$ compound Y $\xrightarrow{\text{pass vapour with steam over } \text{H}_3\text{PO}_4}$ compound Z What is compound Z?

Feb/March 2024

The diagram depicts some laboratory apparatus. Which of these preparations could this apparatus be used for?

May/June 2010

Finish the reaction scheme that begins with propene. In each blank box, give the structural formula of the organic compound that would be produced.

May/June 2010

Organic reactions can involve substances that are atoms, molecules, ions or free radicals. The terms electrophilic, nucleophilic, addition, elimination and substitution are also used for organic reactions. Study the reactions below. Reaction 1: $\text{CH}_4 + \text{Cl}_2 \rightarrow \text{CH}_3\text{Cl} + \text{HCl}$ Reaction 2: $\text{CH}_3\text{CH}_2\text{OH} \rightarrow \text{CH}_2{=}\text{CH}_2 + \text{H}_2\text{O}$ Reaction 3: $\text{CH}_3\text{I} + \text{OH}^- \rightarrow \text{CH}_3\text{OH} + \text{I}^-$ Reaction 4: $\text{CH}_3\text{COCH}_3 + \text{HCN} \rightarrow \text{CH}_3\text{C(OH)(CN)CH}_3$

May/June 2010

Lactic acid, 2-hydroxypropanoic acid, $\text{CH}_3\text{CH(OH)CO}_2\text{H}$, is found naturally in sour milk and in our muscles after strenuous exercise. It is chiral and exhibits stereoisomerism.

May/June 2010

In the reaction sequence shown below, an alkane is changed into a carboxylic acid over several steps. $\text{C}_{10}\text{H}_{22} \xrightarrow{\text{stage 1}} \text{C}_2\text{H}_4 \xrightarrow{\text{stage 2 (catalytic hydration)}} \text{C}_2\text{H}_5\text{OH} \xrightarrow{\text{stage 3}} \text{CH}_3\text{CO}_2\text{H}$. Which processes take place at stage 1 and at stage 3?

May/June 2011

Butanedioic acid is present in amber, algae, lichens, sugar cane and beets. It can be prepared in two stages from $\text{BrCH}_2\text{CH}_2\text{Br}$. $\text{BrCH}_2\text{CH}_2\text{Br} \xrightarrow{\text{step 1}} X \xrightarrow{\text{step 2}} \text{HO}_2\text{CCH}_2\text{CH}_2\text{CO}_2\text{H}$. Which reagents could be used to carry out this synthesis?

May/June 2011

Compound C is used in textile and leather processing. On gentle heating with a few drops of concentrated sulfuric acid, which starting material(s) produce compound C?

May/June 2012

If 1-bromopropane is first reacted with reagent X and then with reagent Y, propanoic acid is formed. Which reagents are X and Y?

May/June 2012

Compound C is used in textile and leather processing. On gentle heating with a few drops of concentrated sulfuric acid, which starting material(s) produce compound C?

May/June 2012

How is a high yield of ethylamine obtained from bromoethane as the starting material?

May/June 2012

Alcohols like methanol, $\text{CH}_3\text{OH}$, are seen as possible substitutes for fossil fuels because they can power car engines.

May/June 2012

Organic chemistry deals with carbon compounds. The reaction types studied are listed below: addition, elimination, hydrolysis, oxidation, reduction, substitution. Addition and substitution reactions are further classified as follows: electrophilic, nucleophilic, free radical. Complete the table below. In the central column, use only the reaction types from the lists above. Use both lists where this is appropriate. In the right-hand column, give the formula(e) of the reagent(s) you would use to carry out the reaction shown.

May/June 2013

Butanedioic acid can be prepared from 1,2-dibromoethane in two stages. $\text{BrCH}_2\text{CH}_2\text{Br} \xrightarrow{\text{step 1}} X \xrightarrow{\text{step 2}} \text{HO}_2\text{CCH}_2\text{CH}_2\text{CO}_2\text{H}$ Which reagents could be used in this synthesis?

May/June 2015

The preparation of 2-hydroxypropanoic acid from ethanol requires a number of stages. $\text{C}_2\text{H}_5\text{OH} \rightarrow \rightarrow \rightarrow \text{CH}_3\text{CH(OH)CO}_2\text{H}$ Which of the following statements about this synthesis are correct?

May/June 2016

Which syntheses will succeed?

May/June 2016

A reaction sequence beginning with propan-1-ol is displayed.

May/June 2016

X and Y are the reagents needed to change 1-bromopropane into butanoic acid. Which substances are X and Y?

May/June 2017

What reagent could be used to perform the reaction shown below?

May/June 2018

The ester $\text{C}_2\text{H}_5\text{CO}_2\text{CH}_2\text{CH}_2\text{CH}_3$ may be prepared in a school or college laboratory by using compound Z as the only organic starting material in a route of four reactions or fewer. What could the identity of compound Z be?

May/June 2018

Which reaction results in an organic anion with a high yield?

May/June 2020

Butanoic acid may be made from 1-bromopropane in two steps by using reagents V and W, as indicated below. $\text{1-bromopropane} \xrightarrow{\text{reagent V}} \text{compound Q} \xrightarrow{\text{reagent W}} \text{butanoic acid}$ What could be reagents V and W?

May/June 2020

C, D and E are isomers of one another. They are formed by passing alcohol vapour over an aluminium oxide catalyst.

May/June 2020

Butanoic acid is made starting from 1-bromopropane. The synthesis involves two reactions carried out in sequence. Which compound is produced in the first stage of the synthesis?

May/June 2021

Hexadeca-10,12-dien-1-ol is made by silk moths from hexadecanoic acid through a three-stage enzymic process. Which row gives the correct descriptions of these three stages?

May/June 2021

Compound X can be changed into compound Y in one step. What might X be?

May/June 2021

The synthesis route illustrated may be used to produce propan-1-ol. step 1 $\rightarrow$ compound X $\rightarrow$ step 2 Which row shows the reagents that are correct for steps 1 and 2?

May/June 2021

S has molecular formula $\text{C}_4\text{H}_{10}\text{O}$ and is a secondary alcohol.

May/June 2021

The skeletal formula of M is shown. M is treated with an excess of LiAlH$_4$. Dilute acid is then added. What is the molecular formula of the final organic product?

May/June 2022

Liquids that include molecules of T have a lemon scent. The structure of T is shown in Fig. 3.1.

May/June 2022

Two separate samples of compound X were each reacted with different reagents, and each reagent was added in excess. The products formed in these two reactions are shown. Which reagents might be used for reaction 1 and reaction 2?

May/June 2023

At room temperature, HBr adds to methylbut-2-ene, giving compound X as the main product. When compound X is treated with KCN in ethanol, compound Y is formed. Acid hydrolysis of compound Y produces compound Z. Which compound is Z?

May/June 2023

Ethanol is manufactured in industry by reacting ethene with steam, with $\text{H}_3\text{PO}_4$ present as the catalyst. Reaction 1: $\text{C}_2\text{H}_4(g) + \text{H}_2\text{O}(g) \rightleftharpoons \text{C}_2\text{H}_5\text{OH}(g)$

May/June 2023

Tartaric acid occurs in some wines. It can be made in the laboratory in two steps. $\text{OHCCHO} \xrightarrow{\text{step 1}} \text{intermediate} \xrightarrow{\text{step 2}} \text{HO}_2\text{CCH(OH)CH(OH)CO}_2\text{H}$ Which reagents may be suitable for this synthesis?

Oct/Nov 2010

The diagram illustrates part of the structure of strobilurin, a fungicide. R and R' denote inert groups. After strobilurin is heated with aqueous sulfuric acid, and the product obtained is then exposed to hydrogen in the presence of a palladium catalyst, what might be the structure of the final product?

Oct/Nov 2010

Tartaric acid occurs in certain wines. It can be prepared in the laboratory in two stages. $\text{OHCCHO} \xrightarrow{\text{step 1}}$ intermediate $\xrightarrow{\text{step 2}} \text{HO}_2\text{CCH(OH)CH(OH)CO}_2\text{H}$. Which reagents would be suitable for this synthesis?

Oct/Nov 2010

In a reaction sequence, ethanal is transformed into compound H. $\text{CH}_3\text{CHO} \xrightarrow[\text{NaCN}]{\text{HCN}} F \xrightarrow{\text{hot dilute } \text{H}_2\text{SO}_4} G \xrightarrow[\text{trace of conc. } \text{H}_2\text{SO}_4]{\text{CH}_3\text{OH, heat}} H$ What might H be?

Oct/Nov 2011

Six compounds, P-U, are shown by their structural formulae.

Oct/Nov 2011

But-2-ene-1,4-diol is changed in two stages via an intermediate $X$ to ketobutanedioic acid.

Oct/Nov 2012

Chloroethane may be prepared from bromoethane in two steps. $\text{C}_2\text{H}_5\text{Br}$ $\xrightarrow{\text{step X}}$ $\text{C}_2\text{H}_5\text{OH}$ $\xrightarrow{\text{step Y}}$ $\text{C}_2\text{H}_5\text{Cl}$ Which of the following statements about these steps are correct?

Oct/Nov 2012

The ester $\mathrm{C_2H_5CO_2CH_2CH_2CH_3}$ may be synthesised in a school or college laboratory by carrying out a sequence of reactions that uses compound X as the only organic starting material. Which compound could X be?

Oct/Nov 2013

A sequence of reactions starting from propan-1-ol is shown.

Oct/Nov 2014

Starting from iodoethane, which reaction sequence would give propanoic acid as the main product in good yield?

Oct/Nov 2015

When compound Z is warmed with concentrated acidified potassium manganate(VII), an equimolar mixture of $\text{CO}_2$ and $\text{CH}_3\text{COCH}_2\text{CH}_2\text{CH}($\text{COCH}_3$)\text{CH}_2\text{CO}_2\text{H}$ is produced. What might the structural formula of Z be?

Oct/Nov 2015

If the initial substance is iodoethane, which reaction pathway would give propanoic acid as the principal final product in good yield?

Oct/Nov 2015

Each compound shown below is reacted on its own with excess $\text{NaBH}_4$. The resulting product from each reaction is then heated with excess concentrated $\text{H}_2\text{SO}_4$. For each case, one or more products are produced with molecular formula $\text{C}_7\text{H}_{10}$. Which compounds produce only a single final product with molecular formula $\text{C}_7\text{H}_{10}$?

Oct/Nov 2015

A section of the structure of a fungicide, strobilurin, is shown below. R and R' are inert groups. In this reaction, strobilurin is heated with aqueous sulfuric acid, forming compound X. Compound X is then reacted with hydrogen in the presence of a nickel catalyst, giving compound Y. What could the structure of compound Y be?

Oct/Nov 2016

Citric acid may be changed into tricarballylic acid in two steps. A промежmediate, $Q$, is produced. Which reagents are required for each step?

Oct/Nov 2017

An ester that has a banana-like smell has the formula $\text{CH}_3\text{CO}_2\text{CH}_2\text{CHCH}_2\text{CH}_3$ (with a $\text{CH}_3$ group attached to the central carbon). Which pair of reactants, when reacted under suitable conditions, would form this ester?

Oct/Nov 2017

Citric acid may be changed into tricarballylic acid in two steps. A compound intermediate, Q, is produced. Which reagents are required for each step?

Oct/Nov 2017

3-oxobutanoic acid may be made in a two-step sequence. $X \rightarrow Y \rightarrow$ 3-oxobutanoic acid What might the structure of $X$ be?

Oct/Nov 2018

Which compound can be converted into propanoic acid by using just one reagent?

Oct/Nov 2018

$3$-oxobutanoic acid may be prepared in a two-step route. $X \rightarrow Y \rightarrow \text{3-oxobutanoic acid}$ What might the structure of $X$ be?

Oct/Nov 2018

The diagram sets out a reaction pathway that begins with ethanal.

Oct/Nov 2018

A student changes 1-iodopropane, $\text{C}_3\text{H}_7\text{I}$, into butanoic acid, $\text{C}_3\text{H}_7\text{CO}_2\text{H}$, through a two-step chemical synthesis. Which reagent is used with 1-iodopropane in the first of the two steps?

Oct/Nov 2020

The reactions of compound G are illustrated.

Oct/Nov 2020

Butanoic acid may be prepared from $1$-bromopropane in two steps. stage $1$ $\text{CH}_3\text{CH}_2\text{CH}_2\text{Br} \rightarrow \text{CH}_3\text{CH}_2\text{CH}_2\text{CN}$ stage $2$ $\text{CH}_3\text{CH}_2\text{CH}_2\text{CN} \rightarrow \text{CH}_3\text{CH}_2\text{CH}_2\text{CO}_2\text{H}$ What are the reaction types for stage $1$ and stage $2$?

Oct/Nov 2021

B is a liquid with a fruity odour. The reaction scheme shows the preparation of B from ethanol, $\text{C}_2\text{H}_5\text{OH}$.

Oct/Nov 2021

Compound $\text{B}$ is a fruity-smelling liquid. The reaction scheme shows how $\text{B}$ can be prepared from ethanol, $\text{C}_2\text{H}_5\text{OH$.

Oct/Nov 2021

Compound $R$ may be prepared from 1-bromopropane by first carrying out a nucleophilic substitution reaction and then an oxidation reaction. What is the identity of $R$?

Oct/Nov 2022

Which compounds could be used to prepare $Y$ in one step?

Oct/Nov 2022

Propyl propanoate may be made in three stages, with propanenitrile as the sole organic starting material. During step 1, the nitrile is changed into compound X. During step 2, compound X is changed into compound Y. During step 3, compound Y is reacted with additional compound X to produce propyl propanoate. $\text{CH}_3\text{CH}_2\text{CN} \rightarrow X \rightarrow Y \rightarrow \text{CH}_3\text{CH}_2\text{CO}_2\text{CH}_2\text{CH}_2\text{CH}_3$ Which reagents would be suitable for step 1 and step 2?

Oct/Nov 2022

Compound $R$ may be produced from 1-bromopropane by means of a nucleophilic substitution reaction, followed by an oxidation reaction. What is the identity of $R$?

Oct/Nov 2022

In a single-step reaction, which compounds could be used to produce $Y$?

Oct/Nov 2022

Propanoic acid can be prepared from bromoethane by means of a two-stage synthesis. Which pair of reagents is the most appropriate?

Oct/Nov 2023

Propanoic acid may be converted into propene through a two-stage synthesis. Which row gives reagents that are suitable for this synthesis?

Oct/Nov 2023

Propanoic acid may be prepared from bromoethane by using a two-stage synthesis. Which pair of reagents would be most suitable?

Oct/Nov 2023

The figure outlines a synthetic pathway for making 1-methylcyclohexanol. $\text{(methylcyclohexene)} \xrightarrow{\text{HBr}} \text{product X} \xrightarrow[\text{heat}]{\text{reagent Y}} \text{1-methylcyclohexanol}$ What is the identity of reagent Y?

Oct/Nov 2024

X and Y are the reagents needed to change 1-bromopropane into butanoic acid. $\text{CH}_3\text{CH}_2\text{CH}_2\text{Br} \xrightarrow{X} \text{CH}_3\text{CH}_2\text{CH}_2\text{CN} \xrightarrow{Y} \text{CH}_3\text{CH}_2\text{CH}_2\text{CO}_2\text{H}$ What are the correct identities of reagents X and Y?

Oct/Nov 2024