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9 Cards in this Set
- Front
- Back
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When do alcohols show acidic properties? |
Only in reaction with the 1st or 2nd group of metals in the periodic table, alcohols are very weak acids. 2CH3-CH2-OH + 2Na --> 2CH3-CH2-ONa (sodium ethoxide) + H2 |
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Substitution |
hydroxyl group is replaced by a nucleophylic substituent CH3-CH(-OH)-CH3 + HCl --> CH3-CH(-Cl)-CH3 +H2O |
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Lucas test |
With the Lucas test we can identify primary, secondary or tertiary alcohols in reaction with a mixture of HCl and ZnCl2. Chloroalkanes are formed - primary have no reaction is water, secondary solution turns milky after a few minutes and tertiary immediately. |
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Elimination |
It's a dehydration reaction - H2O is removed from alcohols and gives alkenes. Concentrated H2SO4 or high temperature and a catalyst (Al2O3) can be used. CH3-CH2-OH -(H2SO4)-> H2O +CH2=CH2 |
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Combustion of ethanol |
CH3-CH2-OH + 3O2 --> 2CO2 + 3H2O |
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Oxidation of primary alcohols |
Primary alcohols are oxidised by a gentle oxidising agent to aldehydes and by strong OA (KMnO4) to carboxylic acids. CH3-CH2-OH -(heat)-> CH2-C(-H)=O -(KMnO4)-> CH3-C(-OH)=O ethanoic acid |
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Oxidation of secondary alcohols |
Secondary alcohols are oxidised into ketones. CH3-CH(-OH)-CH3 -[O]-> CH3-C(=O)-CH3 propanone |
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Oxidation of tertiary alcohols |
Tertiary alcohols don't react with oxidising agents because the formation of a double C-O bond is impossible. |
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How can ethanol be made? |
1. By alcoholic fermantation C6H12O6 -(ethanol)-> 2C2H5OH + 2CO2 2. Chemical synthesis a) chloroethane by hydration Cl-CH2-CH3 + H2O --> OH-CH2-CH3 + 2CO2 b) ethene by hydration CH=CH2 + H2O --> CH3-CH2-OH |
