Kirill L9+10 0.0 / 5 ? PharmacyAlkene and alkynesUniversityNone Created by: RscottqubCreated on: 22-03-19 15:08 How can we produce alkenes? elimination of alcohols . Elimination of haloalkanes (ie OH acting as base) 1 of 21 E2 reaction elimination 2nd order. rate = k[HA][base] . doesnt involve intermediate. 2 of 21 E1 reaction elimination 1st order. rate =k[HA] . involves intermediate . 3 of 21 process E1 1. Halogen leaves 1st since it is good leaving group --> intermediate. 2. base attacks H on adjacent carbon 4 of 21 process E2 all that happens in E1, but all at once/ all in 1 step 5 of 21 Regioselectivity of E1 2 products are formed, in unequal quantities 6 of 21 Which elimination produces more stable alkenes E1, produces more substituted alkene ` 7 of 21 E2 prefers what type of derivative 3>2>1 (opposite to SN2) 8 of 21 secondary derivative will undergo NOT A MIXTURE OF E1/2 - it is not like SN1/2 - look at product to decide 9 of 21 Bond length shortest to longest triple, double, single 10 of 21 Stability of = highest to lowest tetrasub , tertiary sub, E- disub, Z- disub, terminal sub, monosub 11 of 21 other ways to produce alkenes partial reduction of alkynes using lindlar catalyst- +H2. Reduction alkynes using Na in liquid NH3 12 of 21 ways to produce alkynes Double elimination of halogenalkane- must start with disub haloalkane 13 of 21 Markovmikov rule if HX is added to alkene, the H will attach to C with fewer alkyl groups, the X will attach to C with the most alkyl groups 14 of 21 in electrophillic addition reactions major and minor product are always produced false- only major minor if unsymmetrical alkene was started with 15 of 21 ways to turn alkene --> alcohol 1. alkene plus water with acid (h3O+) presence 2. addition of borane followed by oxidation 16 of 21 conditions for boration followed by oxidation BH3, H20, H2O2 , OH 17 of 21 1st step hydroboration- borane is regioselctive - where B attaches is position the OH group will ultimatley end up in . B added to side with less stable carbon 18 of 21 others steps involved hydroboration, oxidation, hydrolysis 19 of 21 electrophillic addition of alkynes produces di halogenalkane 20 of 21 boration and oxidation of alkynes produces aldehyde (not alcohol like alkenes) 21 of 21
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