Organic Condensation Polymers 1. Polyesters

In this video I look at the use of the two main reducing agents employed in organic chemistry. These are lithium aluminium hydride (lithal) and sodium borohydride. I outline the mechanism (nucleophilic addition) in which hydride ions react with C=O groups to form alcohols via alkoxide intermediates. I compare the reactivities of the two reducing agents and discuss the explosive risks associated with using lithium aluminium hydride with protic solvents such as water or methanol. A practical setup, that could be used to reduce aldehydes and ketone with lithal, is presented at the end. It is one in a series of short videos looking at the main organic practical techniques: heat & distill; reflux distillation; washing and drying in solvent extraction; recrystallisation and melting point determination; and others

This video provides an animated explanation of the formation of polyamides from dicarboxylic acids and diamines. The process is known as condensation polymerisation - forming water molecules together with polyamide molecules. In accompanying videos I look at the formation of nylon and at polyesters, including terylene.

In this video I look at the preparation of carboxylic acids from four other organic functional groups. First, from primary alcohols and aldehydes by the process of oxidation, and second, from esters and nitriles by the process of either acid-catalysed hydrolysis or alkaline catalysed hydrolysis.

This video looks at the electrophilic addition reaction of hydrogen bromide with an asymmetric alkene (propene). It helps you to rack the movement of electrons and to gain a better understanding of why 2-bromopropane is the major product - in terms of the relative stabilities of the primary and secondary carbocation intermediates.

In this video I look at how (and why) recrystallisation is used to purify an organic solid. It is one in a series of short videos looking at the main organic practical techniques: heat & distill; reflux distillation; washing and drying in solvent extraction; recrystallisation and melting point determination; and others