3.5 Alcohols

They are a homologous series Functional group OH General formula: Cn H2n+1 OH The prefix hydroxy is used if another functional group is present V-shaped on the end High boiling points

The have hydrogen bonding

The carbon with the OH functional group has Primary - only 1 other carbon attached Secondary - 2 other carbons attached Tertiary - 3 other carbons attached

Perfumes/ aftershave Mouthwash Used in manufacture of drugs, detergents and inks

Yes They both have hydrogen bonding

Fermentation Hydration of alkenes

Yeast, sugar and water is heated between 30-40 degrees (37 optimum) After several days the flask will contain around 15% ethanol = mixture of alcohol and water As yeast is living this is a natural process - anaerobic respiration takes place

Glucose ——> ethanol + CO2 Over the arrow: enzymes in yeast Under the arrow: 30-40 degrees

A mixture of ethanol and water The only product - alcoholic drinks

Too low = prevents respiration of the yeast Too high = denatures the enzymes

Fractional distillation Alcohol boils at 80 degrees Water boils at 100 degrees

Renewable sugars used Aqueous solution of ethanol - could be good if small quantities are needed Batch process - labour intensive requiring people to change batches Requires a lot of energy for fractional distillation

Ethene is reacted with water(steam) Using phosphoric acid as a catalyst - H3PO4 Requires high temperature and pressure Done on a large industrial scale that the majority of alcohols are made from

First arrow from the double bond of the alkene to the H+ ion A carbocation is formed - second arrow from the lone pair of the oxygen in water to the positive carbon The water is now attached to the chain with a + charge on the oxygen - the arrow goes from the middle of the O-H on to the oxygen The alcohol and H+ ion are the final products

Non renewable as the alkenes are from crude oil Fast continuous process Pure product - better for larger quantities

The phosphoric acid It takes part in the reaction but is still considered a catalyst as it is regenerated at the end

No overall carbon dioxide emissions

Plants absorbing CO2 via photosynthesis Fermented into ethanol (5-10%) used in biofuels in cars - as it burns nicely with less CO2 produced Combustion - when the biofuel is used in the cars producing little CO2 The CO2 taken in balances that which is given out

Turns the alcohol back into an alkene by removing water from it

Ceramic wool is soaked in an alcohol and heated with aluminium oxide granules OR Using phosphoric acid as a catalyst (not the aluminium oxide)

First arrow from the lone pair on the oxygen in the alcohol to the H+ ion On intermediate where the H is attached to the alcohol (like water attached) - first arrow from the middle of the C-O to the oxygen Then from a the middle of a C-H bond to the middle of the C-C bond Forming an alkene, water and a H+ ion

Combustion producing CO2 + H2O

Acidified Potassium dichromate (VI) • often acidified with dilute sulphuric acid [O] - you use this as oxygen when balancing

Orange to green Dichromate (VI) ions are orange Chromate (III) ions are green