StAC Level 2 Chemistry 2016

Monday 5 September 2016

Friday 2 September 2016

Haloalkanes are a very useful intermediate compound, often used when converting one useful compound into another. Their own uses are limited, primarily due to the impact they have on the environment. Haloalkanes are generally immiscible (insoluble in water) as they are (technically) non-polar.

Haloalkanes are the products of:

reacting a halogen (such as bromine) with hydrocarbons.
reacting an alcohol with Lucas Reagent (chloroalkanes produced); remember that tertiary alcohols react very quickly, while primary alcohols may not react at all.
reacting an alcohol with PCl₃, PCl₅ or SOCl₂

Haloalkanes can be converted into:

alkenes, using NaOH (or KOH) dissolved in alcohol (elimination reaction)
alcohols, using aqueous NaOH (or KOH) (substitution reaction)
amines, using excess NH₃ (substitution reaction); if you use do not use enough NH₃, it will make an amino salt instead, such as ethyl ammonium chloride

For more information about haloalkanes, click HERE (ChemGuide)

Friday 26 August 2016

Alcohols

INTRODUCTION

The structure of alcohols tells us a lot about their physical properties and chemical reactions. Last year, the first lesson was about the different isomers of C₄H₉OH, with the students starting by trying to make (and name) all of the ones that contain the alcohol functional group. Can you name these?

PREPARATION

There are a few ways to make alcohols:

fermentation of sugars
synthesis gas
hydration of alkenes

We looked at the hydration of 1-butene using dilute sulfuric acid:

REACTIONS

In this topic, we will do some experiments with primary, secondary and tertiary alcohols. Here are some videos explaining some of the expected observations and how to use them to identify/classify alcohols.