20.2 Synthetic Routes

The following three step synthesis route was carried out:

A    B  C  D 

Reactant A is a hydrocarbon containing 85.71% carbon and shows 4 peaks in a ¹H NMR spectrum. Deduce the identity of A.

Intermediate B shows a fragment at m/z 43 in the mass spectrum and has a molecular ion at m/z 74.

Deduce the identity of B, giving a reason.

The question is about intermediate C in the synthesis.

[1]

Deduce the identify of the reaction product, D, and give one piece of spectral data that would support your answer.

Benzene and cyclohexene are two hydrocarbons that are able to react with bromine. State the type of reactions in each case.

Benzene can be converted into nitrobenzene in a one step reaction. State the names of the reagents needed for the reaction and the formula of the electrophile in the reaction.

Outline the mechanism of the reaction between benzene and the electrophile in part c)

Aniline is useful precursor for making synthetic dyes. It can be made from nitrobenzene in a two step synthesis. Give the reagents and conditions for the reaction.

For the reaction profile outlined in the reaction profile below, state the mechanism or type of reaction for steps 1 and 2. 

Propane  1-bromopropane  Compound X  Propanal 

Step 1 ...............................................................

Step 2 ...............................................................

Outline the mechanism for step 2.

Compound X can be oxidised by the reaction with acidified potassium dichromate to give propanal. Compound X will oxidise to propanoic acid if allowed to fully oxidise. Explain how full oxidation can be prevented. 

State the following for step 1.

Reagents and conditions ..........................................

Mechanism ..........................................

The following reaction pathway is used to produce Compounds A and B, which when reacted together, form a branched ester molecule, Compound C. 

Suggest suitable reagents and conditions for the synthesis of Compound A via Step 1 and give the name for this type of reaction.

In order for the ester to be produced, the ketone in part (a) must be converted to another compound, B.

Outline how ethanol can be synthesised from ethane in two steps. State the reaction conditions and reagents and name the type of reaction taking place.

The four step synthesis to form propan-1-ol from a ketone is outlined below.

Propanal is a versatile organic building block used in the synthesis of plastics and rubber chemicals.

Propanal can be produced from propanoic acid in the following two-step reaction. 

	Step 1		Step 2
Propanoic acid		Propan-1-ol		Propanal

State the reaction type, including suitable reagents, for Steps 1 and 2.

Suggest why it is not possible to convert propanoic acid directly to propanal using the reagent you identified for Step 1 in (a).

Explain why Step 2, in (a), is completed by distillation.

Identify, explain your reasoning, which of the three organic compounds, from the reaction scheme in (a), would be distilled first.

State four factors that should be considered when designing a reaction scheme for the synthesis of a target molecule in industry.

1-(3-Aminophenyl)ethanol can be synthesised according to the following three-step reaction scheme.

Step 1 involves a reaction at position 3 of the benzene ring of 1-phenylethan-1-one. 
 

State the reaction type, including suitable reagents, for Step 1.

State a suitable reagent for Step 2, in (b).

In Step 3 of the reaction scheme from (b), compound C is heated with hydrochloric acid in the presence of a tin catalyst to form the final product, 1-(3-aminophenyl)ethanol. 

Explain why Step 3 is a reduction reaction.

Suggest a reaction scheme, using displayed formulae, that could be used to prepare a sample of propyl propanoate. 

Conditions and reagents are not required.

One of the intermediates in the reaction scheme, from (a), has a molecular mass of 74.09 g mol^-1.
 

Propanal and the intermediate (M_r = 74.09) in the reaction scheme, from (a), are to be separated by distillation.

Explain which chemical will distil first.

One of the intermediates in the reaction scheme, from (a), has a molecular mass of 60.09 g mol^-1.