medical entrance tips

ALKYNES
1. Generic formula - CnH2n-2
2. Propargyl goup -CH º C - CH2-
3. Dipropargyl CH º C- CH2 - CH2 C º CH, 1,5 - Hexadiyne(Openchain isomerof benzene)
4. Alkynes are isomeric with Dienes (functional isomerism)
5. Alkynes exhibit chain isomerism, position isomerism and functional isomerism
6. CaC2 with water gives acetylene
7. Mg2C3 with water gives allylene (CH3C º CH)
8. Iodoform when heated with Ag powder gives acetylene
9. Alkynes are obtained by the dehydrohalogenation of gem and vic - dihalides
10. Dehalogenation of tetrahalides with zinc
11. By the electrolysis of a concentrated solution of Sodium salt of maleic acid or fumaric acid
12. Acetylene is obtained by the hydrolysis of acetylides
eg:- C2Na2, C2Cu2, Ag2C2
13. Acetylene is readily soluble in acetone
14. Temperature of oxy-acetylene flame > 3000°C
Addition reactions
1.Reduction:
RC º CR1 ________________> RCH = CR1 Cis olefin
RC º CR1 _________> R CH = CH R1 trans olefin
RCº CR1 __________ > RCH = CHR1 ______> R CH2CH2 R1

Lindlar’s catalyst Pd - CaCO3 or Pd / BaSO4 ( partially poisoned with lead tetra acetate)
2. Addition of Halogen acids ___ gem dihalide is formed
RC º C-R + H Br ___> RCH = C -Br ______> R CH2 C Br2
3. Addition of Halogens
RC º C-R ______> R CBr = C Br ______> RC Br2 - RCBr2
4. Acetylene tetrachloride is commercialy is known westron
5. Oxymercuration- addition of water - Aldehydes or ketones
CH º CH _________> CH2 = CHOH __ _________________> CH3CHO

CH3C º CH _________> CH3 - COH = CH2 ____________________> CH3 _ COCH3
6. Addition of HOCl
CH3C º CH + HOCl ___> CH3 - COH = CHCl ___> CH3 -C(OH)2 - CH2Cl2



7. Hydroboration
RC º CR1 ______> (RCH = CR1)3 B _________> RCH = CHR1
Cis olefin