Mind Map Chemistry.doc

ALKENES & ALKYNES Definition & Classification  Hydrocarbon with carbon-carbon    

double bond.* General formula CnH2n* Hydrocarbon with carbon-carbon triple bond. General formula CnH2n-2 Both are unsaturated hydrocarbon because they contain less hydrogen per carbon.

Nomenclature  Choose longest chain with C=C as parental chain with -ene- suffix.*  Number the carbon atom beginning with the end nearest to the C=C.  Side chain act as prefix and parental chain as suffix.  Side chain named alphabetically and position on parental chain indicated.  In naming parental alkene, position of C=C indicated by smaller number of attachment point.  Alkyne naming is similar except C C as parental chain with -yne- suffix.

INDICATOR * Express Alkenes Express Alkynes Express Both Alkenes Alkynes

Cracking  

[CH2-CH2] n Steam Dehydrogenation800°C process

[CH2=CH2] n + H2

ALKENES PREPERATION Dehydrohalogenation Dehydration of Alcohol   

CnH2n+1OH [CH2=CH2] n + H2O Alcohol vapour is passed through hot alumina @ heated with excess sulphuric acid

Hydrohalogenation

[CH2=CH2] n +HX

CnH2n+1X

If according to Markonikoff produce major product If according to anti Markonikoff produce minor product

CnH2n+1X -HX

[CH2=CH2] n + H2

KOH (in alcohol)



Haloalkane boiled in potassium hydroxide dissolved in alcohol

Halogenation

[CH2=CH2] n + X

n [CH2-CH2] X2

via electrophilic addition

Hydration

[CH2=CH2] n +H2O

CnH2n+1OH

Catalyst phosphoric acid at 300°C

Hydrogenation

[CH2=CH2] n +H2

n [CH2-CH2]

ALKENES REACTIONS Oxidation

[CH2=CH2] n

n [CH2-CH2] (OH)2

Reaction in Bromine Water

Test for alkene unsaturation Br2

[CH2=CH2] nH2O Addition of Sulphuric Acid

[CH2=CH2] n +H2SO4

n [CH2-CH2] OHBr

Via electrophilic addition

n [CH2-CH2] H2SO4 (alkyl hydrogen sulphate) Polymerisation

[CH2=CH2] n

[CH2=CH2] n

Peroxide 1000°C

70°C Al(C2H5)

n [CH2-CH2]

n [CH2-CH2]