Alcohols are useful solvents in cosmetics. They can bond with both water and oils due to their hydroxyl (-OH) group. Common alcohols used in cosmetics include ethanol, methanol, glycerol, propanol, and cetyl alcohol. Alcohols dissolve active ingredients that do not dissolve in water alone. Smaller alcohols can be used to create emulsions and prevent oil and water from separating. Glycerol in particular is useful for dissolving natural oils in skin creams due to its three hydroxyl groups.

1. Alcohol (This powerpoint is narrated. Make sure your speakers are turned up before starting.)

2. Describe the useful chemical and physical properties of alcohols as solvents Describe the uses of alcohols in cosmetics Exam Objectives

3. An alcohol is a carbon-based compound with an -OH (hydroxyl) group attached to it. They can form bonds with both water and oils because of this group. Traditionally, alcohol was produced by fermentation Industrially we can produce alcohols by hydrating alkenes in the presence of a catalyst Alcohols

4. The most common is Ethanol. We have also used Methanol and glycerol. Cosmetic products can often also contain propanol, benzyl alcohol, propylene glycol, ethylene glycol, cetyl alcohol, cetearyl alcohol, stearyl alcohol, phenoxyethanol. Common alcohols

5. The homologous series of alcohols: Has the general formula CnH2n+1OH. Have names which end with –ol Become less soluble in water as the chain length increases, but more soluble in organic liquids Have higher boiling points than similar hydrocarbons, with ethanol boiling at 78.3°𝐶 They are therefore liquids at room temperature Useful properties

6. Alcohols are used as solvents in cosmetics to dissolve active ingredients that won’t dissolve in water. Smaller alcohols can be used to create emulsions, preventing oily and watery layers from separating out. Glycerol has 3 hydroxyl groups so it is very useful in skin creams for dissolving natural oils. As Solvents

7. What do beauty therapy sites think about the use of alcohol in cosmetics? (do they understand it’s importance?) What are the implications for safety, sustainability and the environment with using alcohols as solvents? Can you explain why small alcohols can mix with water while larger ones mix better with oils? Questions to consider

8. From the Extension textbook, answer the questions in the main text and the Summary questions. (If you go interactive it will show you the link to these) Extension Work