Alcohols Flashcards
What is a diol
Has two OH groups
What is a triol
Has three OH groups
Why does bp of alcohols increase with molecular size
Due to increased strength of van der waals forces as more electrons which require more energy to overcome
Why do alcohols have higher bps than similar molecular mass alkanes
Due to added presence of inter-molecular hydrogen bonding between OH groups and permanent dipole-dipole forces meaning more energy is required to separate the molecules
Process of chlorination with primary alcohols
Phosphorus pentachloride (PCl5) which is a white solid reacts vigorously with alcohols to form chlorolkanes
PCl5 + CH3CH2OH ——> CH3CH2Cl + POCl3 + HCl (misty fumes so can be used to test for OH)
Process of chlorination in tertiary alcohols
Shake with concentrated hydrochloric acid at room temperature
(CH3)3C-OH + HCl ——-> (CH3)3C-Cl + H2O
Process of bromination in alcohols and two step reaction
-mixture of potassium bromide and 50% concentrated sulfuric acid warmed with the alcohol
KBr + H2SO4 ——> HBr + KHSO4 (to make HBr)
HBr + CH3CH2OH ——> CH3CH2Br + H2O
Process of iodination in alcohols and two step reaction
Carried out using red phosphorus and iodine as iodine alone would react too readily with sulfuric acid
2P + 3I2 ——> 2PI3(phosphorus triiodide)
3C2H5OH + PI3 ——> 3C2H5I + H3PO3 (phosphoric (III) acid)
Why does solubility In water decrease as alcohol chain size increases
As the non-polar character increases and dominates so hydrogen bonding with water is less efficient although there is still hydrogen bonding between the alcohols and water, these are not sufficient to interrupt the hydrogen bonding network in water as the London forces begin to become as strong as hydrogen bonding between water molecules
What do alcohols react with sodium to produce
2Na + 2CH3CH2OH ——> 2CH3CH2O(-)Na(+)(sodium ethoxide) + H2(HYDROGEN)
What are the three things alcohols can be oxidised to
Aldehydes, ketones and carboxylic acids
What are primary alcohols oxidised to
Aldehydes then carboxylic acids
What are secondary alcohols oxidised to
Ketones
What are tertiary alcohols oxidised to
No change
What colour is potassium dichromate and when reduced and formula
Orange (6+ chromium) to green (3+), K2Cr2O7
