Hydrocarbons Flashcards
(21 cards)
Hydrogenation(prep of alkane)
Alkene –Pt/Pd/Ni–> CH3-CH3
prep of alkane from alkyl halides
CH3-Cl —Zn, H+—> CH4 + HCl
wurtz reaction(prep of alkane)
R-X + 2Na + X-R –Dry ether–> R-R + 2NaX
decarboxylation
add soda lime(NaOH plus CaO) plus heat to smth like(RO- M+)
OR
kolbe’s electrolysis
electrolysis of smth like(RO-M+)
halogenation
ex CH4 + Cl2 —hv—> CH3Cl3 + HCl
Mechanism
1. Initiation: homolysis of Cl2
Cl-Cl –hv, homolysis–> Cl* + Cl(free radicals)
2. propogation:
CH4 +Cl –hv—> CH3* + HCl
CH3* + Cl-Cl –hv–> CH3-Cl + Cl*
3. termination
Cl* + Cl* –> Cl2
CH3 + CH3 –> (CH3)2
CH3 + Cl –> CH3Cl
controlled oxidation
2Ch4 + O2 –Cu/523K/100atm–> 2CH3OH(methanol)
CH4 + O2 –Mo2O3, heat–> HCHO(methanal) + H2O
2Ch3Ch3 + 3O2 —(Ch3COO)2Mn, Heat–> 2Ch3Cooh(ethanoic acid) + 2H2O
(CH3)3CH —KMnO4—-> (CH3)3COH
Isomerisation
C6H14 —Anhydrous AlCl3/HCl–> like 4 chained with 1 branch both products are positional isomers
Aromatization
Six or more carbon chain are cyclised to bezene and its homologues
Reagents :- Cr2O3, 773K, 10-20atm
Reaction with steam
CH4 + H2O –Ni, Heat–> CO + 3H2P
Pyrolysis/Cracking
Higher alkanes on heating to higher temperature decompose into lower alkanes, alkenes etc
prep of alkene from alkynes
RC≡CR + H2 –Pd/C–> cis alkene(R and H)
RC≡CR + H2 –Na/liquid NH3–> trans aklene
prep of alkene from alkyl halides(dehydrohalogenation)
CH3CH2X —alc KOH-> Ethene
prep of alkene from vicinal dihalides(dehalogenation)
CX-CX + Zn —> C=C + ZnX2
prep of alkene from alchols(dehydration)
CH3CH2OH —conc H2SO4, Heat–> Ethene
addition of sulphuric acid to alkene
has to be cold and dil, follow markonikov rule(H) and (OSO2OH)
addition of water to alkene
follows markonikov rule
Oxidation
Alkene + H2O + O –dil KMnO4, 273K–> OH is added to both C of double bond
Ozonolysis
Alkene + O3 —> squid game ahh structure at double bond
which is unstable to it breaks into two aldehydes of of both sides of the double bond
O ⸺
/ \ |
C C | Squid game ahh structure
O ⸺ O ⸺
| |
Polymerisation
n(CH2=CH2) —High temp/pressure, Catalyst–> –(–CH2-CH2–)n–
if any C that are not in the double bond, add them as branch
Cyclic polymerisation
3 Ethyne
one bond of each is moves as a hexagonal structure to make beneze in a red hot iron tube at 873K
Alkene to Alkyne
Halogenate Alkene
alc KOH (dehydrohalogenation)
CH2=CHBr left, add NaNH2
