Hydrocarbons Class 11 CBSE Revision notes, Study notes of Chemistry

Download Hydrocarbons Class 11 CBSE Revision notes and more Study notes Chemistry in PDF only on Docsity! Hydrocarbons  Compounds of carbon and hydrogen.  Classification of Hydrocarbons: Alkane  Open chain saturated hydrocarbon with general formula (CnH2n+2).  All the C atoms are single bonded i.e. sp3 hybridised. Conformations of Alkane  Conformations are the different arrangement of atoms that can be converted into one another by rotation about single bonds.  Eclipsed Conformation: H atoms on two adjacent carbon atoms are closest to each other i.e. dihedral angle is 0.  Staggered Conformation: H atoms on two adjacent carbon atoms are farthest to each other i.e. dihedral angle is 60. Preparation of Alkanes:  Reduction of Alkyl Halides: RX + Zn: + H+ → RH + Zn2+ + X- 4RX + LiAlH4 → 4RH + LiX + AlX3 (X≠ F) RX + (n - C4H9)3 SnH → R-H + (n - C4H9)3 SnX  Grignard Reagent:  At least one >c=c< (double bond) group i.e. sp2 hybridisation, is present throughout the chain.  Allene: alkene molecule in which at least one C has double bonds with each of the adjacent carbon i.e. -c=c=c- group.  Isomeric with saturated cycloalkanes. Geometric Isomers: Z is used if the higher - priority substituents on each C are on the same side of the double bond.letter E is used if they are on opposite sides Heats of Hydrogenation: Heat of hydrogenation increases with increase in stability of alkene. Order of heat of hydrogenation: 1-Butene> cis-2-Butene > trans-2-Butene Order of stability: 1-Butene> cis-2-Butene > trans-2-Butene Preparation of Alkenes: 1. Cracking of petroleum: 2. Dehydrohalogenation of alkyl halides: RCH2CH2X + alc.KOH → RCH = CH2 3. Dehydration of Alcohols : Saytzeff Rule: In dehydration and dehydrohalogenation the preferential order for removal ofan H is 3° > 2° > 1° 4. Reduction of alkynes: Chemical Properties: 1. Electrophilic Polar Addition Reactions Reagent Product Name Structure Name Structure Halogens (Cl2, Br2 only) X:X Ethylene dihalide CH2XCH2X Hydrohalic acids H:X Ethyl halide CH3CH2X Hypohalous acids X:OH Ethylene halohydrin CH2XCH2OH Sulfuric acid (cold) H:OSO2OH Ethyl bisulfate CH3CH2OSO3H Water (dil. H3O+) H:OH Ethyl alcohol CH3CH2OH Borane H2B:H Ethyl borane (CH3CH2BH2) → (CH3CH2)3B Peroxyformic acid H:O- OCH=O (HCO3H) Ethylene glycol CH2OHCH2OH 2. Addition of Hydrogen Halides to Alkenes: Markovnikov’s Addition: R - CH = CH2 + HBr → R – CHBr – CH3 Mechanism: HAC. 5 eb ee BO, ' Ha OAc}, HO NaBH, ac —e OH i CH, _HaOAC), HO, NABH, CH, H3C UGH Hg{OAc}:. HzO NaBH HC HC 5. Hydroboration-Oxidation: Hydroboration Oxidation Ys 2 poses none + a Se OH a ES , Hoae H OH ‘ Alcohol =| Examples: CH; Chg So (BH), H;0,.0H™ OH Hc SCH HAC 3 OH CH; - OH H eNO he wow ye CH CH CH; CHs H c BH; }; H:02.0H” ° \ ee CHz “CH2 CH; 6. Halogen Addition in Non-polar Solvent: 7. Halogen Addition in Aqueous Medium: 8. Syn – Hydroxylation: Formation of di-oles. 9. Ozonolysis of Alkenes: Aromatic Hydrocarbons: For being aromatic a hydrocarbon should  be a cyclic compounds.  have planarity in geometry.  have complete delocalization of electrons over ring.  follow Huckel Rule i.e. number of ?? electrons in ring = (4n+2). : Benzene (C6H6) 1. Structure: 2. Chemical Reactions of Benzene: Anti-aromatic Hydrocarbons: Highly unstable compounds. Number of π electrons in ring = 4n. Example: