What is distillation (in organic synthesis)?

A distillation is a separation technique in which the reaction mixture is heated so that the product is removed as vapour as it forms, then condensed and collected.

Define target molecule

A target molecule is the desired product of an organic synthesis, towards which a reaction pathway is designed from a given starting material.

True or False? When heating under reflux, the condenser is clamped vertically so that vapours condense and drip back into the flask.

True. The vertical condenser returns vapour to the flask, keeping all reactants and products inside the reaction vessel.

To extend the carbon chain of a molecule, a .......... group is introduced by .......... substitution.

To extend the carbon chain of a molecule, a nitrile group is introduced by nucleophilic substitution.

Why is distillation used rather than reflux when oxidising a primary alcohol to an aldehyde ?

The aldehyde has a lower boiling point than the alcohol and can be distilled off as soon as it forms, preventing further oxidation to a carboxylic acid.

What is the first step when designing a two-stage synthetic route?

Draw the structures of the starting molecule and the target molecule , then determine whether they have the same number of carbon atoms.

When using a separating funnel, if the .......... layer increases in volume after adding water, that layer is the .......... layer.

When using a separating funnel, if the aqueous layer increases in volume after adding water, that layer is the aqueous layer. This test identifies which layer is organic by showing which layer grows when water is added.

True or False? At AS level, synthetic routes are limited to a maximum of two steps.

True. At AS level, you are only required to design a two-step synthesis: reactant → intermediate → product.

What is the purpose of adding a drying agent such as anhydrous magnesium sulfate to an organic product?

To remove traces of water from the organic product; the anhydrous salt absorbs water and can be filtered or decanted away.

State the two-step route to convert chloroethane into ethanoic acid, naming the intermediate.

Step 1: react chloroethane with KCN to form propanenitrile (or with NaOH to form ethanol ). Step 2: oxidise the intermediate using acidified potassium dichromate under reflux to give ethanoic acid .

True or False? An electric heating mantle is preferred over a Bunsen burner for organic reactions because many organic compounds are flammable.

True. Electric heating mantles provide controllable heat without an open flame, reducing the risk of igniting flammable organic compounds.

A LevelChemistryOCRFlashcards4. Core Organic ChemistryOrganic Synthesis

Organic Synthesis (OCR A Level Chemistry A): Flashcards

Exam code: H432

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What is distillation (in organic synthesis)?

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What is distillation (in organic synthesis)?
A distillation is a separation technique in which the reaction mixture is heated so that the product is removed as vapour as it forms, then condensed and collected.
Define target molecule
A target molecule is the desired product of an organic synthesis, towards which a reaction pathway is designed from a given starting material.
True or False?
When heating under reflux, the condenser is clamped vertically so that vapours condense and drip back into the flask.
True.
The vertical condenser returns vapour to the flask, keeping all reactants and products inside the reaction vessel.
To extend the carbon chain of a molecule, a .......... group is introduced by .......... substitution.
To extend the carbon chain of a molecule, a nitrile group is introduced by nucleophilic substitution.
Why is distillation used rather than reflux when oxidising a primary alcohol to an aldehyde?
The aldehyde has a lower boiling point than the alcohol and can be distilled off as soon as it forms, preventing further oxidation to a carboxylic acid.
What is the first step when designing a two-stage synthetic route?
Draw the structures of the starting molecule and the target molecule, then determine whether they have the same number of carbon atoms.
When using a separating funnel, if the .......... layer increases in volume after adding water, that layer is the .......... layer.
When using a separating funnel, if the aqueous layer increases in volume after adding water, that layer is the aqueous layer.
This test identifies which layer is organic by showing which layer grows when water is added.
True or False?
At AS level, synthetic routes are limited to a maximum of two steps.
True.
At AS level, you are only required to design a two-step synthesis: reactant → intermediate → product.
What is the purpose of adding a drying agent such as anhydrous magnesium sulfate to an organic product?
To remove traces of water from the organic product; the anhydrous salt absorbs water and can be filtered or decanted away.
State the two-step route to convert chloroethane into ethanoic acid, naming the intermediate.
Step 1: react chloroethane with KCN to form propanenitrile (or with NaOH to form ethanol). Step 2: oxidise the intermediate using acidified potassium dichromate under reflux to give ethanoic acid.
True or False?
An electric heating mantle is preferred over a Bunsen burner for organic reactions because many organic compounds are flammable.
True.
Electric heating mantles provide controllable heat without an open flame, reducing the risk of igniting flammable organic compounds.

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