4.2.3 (b,c) Synthetic Routes

Syllabus

(b) for an organic molecule containing several functional groups:

(i) identification of individual functional groups

(ii) prediction of properties and reactions

{Learners will be expected to identify the functional groups encountered in Module 4.}

(c) two-stage synthetic routes for preparing organic compounds.

Learners will be expected to be able to devise two stage synthetic routes by applying transformations between all functional groups encountered up to this point of the specification.

{Extra information may be provided on exam papers to extend the learner’s toolkit of organic reactions.}

What does this mean?

Two-step synthesis

Any Organic substance that we wish to synthesise requires raw materials.

And it will contain one or more functional group that is unlikely to exist in the raw material.

So we must identify the functional groups we wish our product to have.

And then we can begin to work out how to produce them from the raw material.

To do this well you need to have a firm mental-map of how to inter-convert the functional groups we've seen so far.

And so far we have looked at Alkanes, Alkenes, Alcohols, Ketones, Aldehydes, Haloalkanes and Carboxylic Acids.

So Lactic Acid is acidic- because it contains an acid group.

It can still be Oxidised, however, because the Alcohol group will Oxidise to a Ketone.

It will be very soluble because it is a smallish molecule that can hydrogen bond in two places.

So if you were asked to synthesise Lactic Acid from Prop-2-enoic Acid...

You could still react with Steam in the presence of Phosphoric Acid catalyst although you would make some 3-hydroxypropanoic acid as well.

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