Chemistry A2 Rings,acids and amines

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  • Chemistry A2 rings ,
    • aldehydes and ketones
      • they bothe contain a C=O functional group
      • aldehydes have the general formula of C=OH
      • the general formula for the ketone is R----C=O----R
      • oxidation of alcohols
        • primary and secondary alcohols can be oxidized by acidified potassium dichromate
        • secondary alcohols when oxidised make ketones
      • they can be reduced back into primary and secondary alcohols by NaBH4
      • testing for aldehydes and ketones
        • 2-4-dimethyl hydrazine (2-4-DNPH)
        • tollens reagent
          • this can be mixed with the aldehyde or ketone
            • if it is an aldehyde it will make a silver mirror for a ketone their will be no reaction
    • carboxylic acids
      • these can be used in all basic acid reactions
        • acid + carbonate ---> salt +CO2 + H2O
        • acid + base ---> H2 + salt + H20
        • acid+alkali ---> salt+ H2O
      • react with alcohols to make esters
        • esters
          • have a general formula of R--COOC--R
          • has to have a conc H2SO4 cat
          • they can also be made by acid anhydrides and Alcohols
    • hydrolysis of esters
      • Acid hydrolysis is when you heat an ester with a dilute acid and makes a alcohol and a carboxylic acid
      • alkali hydrolysis of esters
        • heat ester with dilute NaOH to make a sodium salt and a alcohol
    • Benzene
      • benzene symbol is a hexagon with a circle this is because it is a resonance structure
        • the circle represents the constant movement of electrons round the bonds the electrons form rings above and below the carbon rings
      • due to the movement of these electrons it makes benzene very stable and due to this dense electron center it creates it repels nucleophiles
      • so to attach functional groups you must first make them have a positive charge
      • reactions of benzene
        • halogenation
          • must use an halogen carrier like AlBR3 or FeCL3
          • these cause the halogen to become positive as such a substitution reaction can occur
          • C6H6 + Br2 --AlBr3-->C6H5Br + HBr
        • nitration
          • you need to use an H2SO4 acid catalyst
          • this is the equation
          • When the NO2 group has been attached you can then reduce it using Sn and HCl acid concentrated at 50^oC
        • friedel craft reaction
          • this attaches CH3 groups to benzene in order to make methybenzene
          • you need to use a catalyst like aluminum chloride
          • the reaction is as follows
          • one name for a benzene with a methyl group is Toluene
    • phenol
      • a phenol is benzene with a OH group attached
      • this makes benzene more reactive
      • this means that you can attach other functional groups more easily
      • for example you can attach halogen groups without needing a halogen carrier
        • C6H5OH+3Br2------->C6H2OHBr3+3HBr
      • you can also add nitro groups using dilute nitric acid
        • C6H5--dilute HNO3>C6H4OHNO2
    • phenols
      • this is more reactive then benzene as the oxygen draws the electrons closer to it
      • due to this higher reactivity halogens can react without a halogen carrier
      • reaction with bromine
        • C6H5OH+3 Br2-------->C6H2OHBr3 + 3HBr
      • it will also react with nitric acid without a catalyst to make nitro phenol
      • the reaction with nitric acid
        • C6H5OH+HNO3-------->C6H4OHNO2+H2O
      • Making azo dyes from phenols and properties
        • first phenol is dissolved in  with sodium hydroxide
          • C6H5OH+NaOH------>C6H5O-Na+ +H2O
          • this is then cooled and reacted with cold benzenediazonium chloride
      • other reactions of phenols
        • combustion of phenols
          • C6H5OH + 7O2 -----> 6 CO2+ 3H2O
          • A very plentiful supply of  oxygen is needed
            • this is due to the carbon to hydrogen ratio as oxgen usaly reacts with hydrogen first leaving carbon to group together
        • it can be used to make esters but you don't react  it with carboxylic acids instead you react it with acyl chlorides or acid anhydrides instead
          • acyl chloride reaction
            • C6H5OH + CH3COCl -----> CH3COOC6H5 + H2O
        • you can react it with iron 3 chloride this will give you a violet colored solution
          • this could be a possible test for phenols
    • making azo dyes from amines
      • first you need to make nitric acid
        • NaNO2 + HCl ------> HNO2 + NaCl
        • then you react the nitric aid with phentolamine and hydrochloric acid
          • C6H5NH2 + HNO2 + HCl----> C6H5N+ TRIPLE BOND N CL-+ 2H2O
          • the product formed from this reaction is then reacted with phenol to make a azo dye
            • C6H5N+ TRIPLE BOND N CLC6H5N+ TRIPLE BOND N CL- + C6H5OH ---->C6H5N+==NC6H5OH + HCl
            • making azo dyes from amines
              • first you need to make nitric acid
                • NaNO2 + HCl ------> HNO2 + NaCl
                • then you react the nitric aid with phentolamine and hydrochloric acid
                  • C6H5NH2 + HNO2 + HCl----> C6H5N+ TRIPLE BOND N CL-+ 2H2O
                  • the product formed from this reaction is then reacted with phenol to make a azo dye
                    • C6H5N+ TRIPLE BOND N CLC6H5N+ TRIPLE BOND N CL- + C6H5OH ---->C6H5N+==NC6H5OH + HCl
                  • THIS HAS TO BE DONE AT LOW TEMPERATURES
          • THIS HAS TO BE DONE AT LOW TEMPERATURES

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