4.2.1

• alcohol functional group

  OH
• alcohol suffix


  ol
• alcohol prefix

  hydroxy
• the number of OH groups is shown by a

  numerical suffix
• primary alcohol

  the carbon atom the OH group is bonded to is also bonded to 1 other carbon atom
• methanol alcohol type

  primary
• secondary alcohol

  the carbon atom the OH group is bonded to is also bonded to 2 other carbon atoms
• tertiary alcohol

  the carbon atom the OH group is bonded to is also bonded to 3 other carbon atoms
• boiling point of alcohol compared to alkanes

  alcohols have a higher boiling point than the alkane with the same number of carbons
• alkane boiling point explanation

  alkanes are non polar meaning they only form London forces between molecules these are weak and easy to break giving alkanes low boiling points
• alcohol boiling point explanation

  alcohols are polar molecules due to the difference in electronegativity between the Oxygen and the Hydrogen forming partial charges. So London forces and hydrogen bonds can occur between molecules. Hydrogen bonds are strong and hard to break giving alcohols a high boiling point
• volatility


  how readily a molecule turns into a gas
• volatility of alcohols compared to alkanes

  alcohols are less volatile than alkanes with the same number of carbons as they have higher boiling points so require more energy to change state
• trend of boiling points and carbon chain length between alcohols and alkanes

  the greater the number of carbons in an alcohol the closer its boiling point to the alkane with the same number of carbons
• trend of boiling points and carbon chain length between alcohols and alkanes explanation

  the longer the carbon chain of an alcohol the greater the effect / contribution of the London forces compared to the hydrogen bond
• Solubility of alcohols compared to alkanes

  highly soluble in water compared to the alkane with the same number of carbons
• solubility of alcohols compared to carbons explained

  the OH group in the alcohol forms a hydrogen bond with the water. alkanes are not able to do this as they are non polar
• solubility of alcohols compared to carbon chain length

  the shorter the alcohol carbon chain the more soluble
• solubility of alcohols compared to carbon chain length explained

  the longer the carbon chain the more of the molecule that is unable to form hydrogen bonds
• primary alcohol oxidation using distillation

  primary alcohol + 1 [O] -> aldehyde + water
• when a primary alcohol is in excess during oxidation what forms

  an aldehyde
• why is distillation of an alcohol during oxidation used to form an aldehyde

  aldehydes can easily be oxidised and have a low boiling point and cannot form hydrogen bonds so need to be removed from the reaction solution quickly
• aldehyde functional group

  C=O at the end of the carbon chain
• Primary alcohol oxidation using reflux

  primary alcohol + 2 [O] -> carboxylic acid + water
• when the primary alcohol is the limiting reagent during oxidation what forms

  carboxylic acid
• reflux is used during the oxidation of primary alcohols to form a carboxylic acid because


  it allows the volatile aldehyde to recondense and further react
• once a carboxylic acid is formed from a primary alcohol it needs to be

  distilled to be purified. this can be done as it has a high boiling point
• [O]

  the oxidising agent

  potassium dichromate + sulfuric acid -> K2Cr2O7 / H+ (aq)

  when reduced in a reaction it turns from orange ( dichromate VI ) to green ( chromium III )
• Oxidation of secondary alcohols

  secondary alcohol + 1 [O] + reflux -> ketone + water
• how many times can secondary alcohols be oxidised

  only once as there is only 1 hydrogen atom bonded to the carbon atom that the OH group is bonded to. so its only able to loose 1 hydrogen
• why use reflux during oxidation of secondary alcohols

  increases the amount of ketone formed but means mixture must be distilled afterwards
• ketone functional group

  C=O in the middle of a carbon chain
• tertiary alcohol oxidation

  cannot be oxidised as the carbon atom bonded to the OH group is only bonded to other carbons meaning there is no hydrogen atom available for the reaction. This causes the oxidising agent to stay orange
• dehydration of alcohols

  alcohol + reflux + concentrated acid catalyst -> alkene + water
• alkene functional group

  c=c anywhere on the carbon chain
• alcohols can dehydrate because

  they have the atoms available to lose to form a molecule of water
• after an alcohol is dehydrated

  the alkene must be purified by distillation
• elimination reaction

  a reaction where a smaller molecule is removed from a larger " parent " molecule
• what types of reaction is the dehydration of an alcohol

  elimination reaction
• dehydration of secondary alcohols forms

  structural isomers as the OH group and a hydrogen either side of the carbon atom is removed

  if the c=c occurs in the centre of the chain this can form E / Z stereoisomers