Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
13 Cards in this Set
- Front
- Back
|
Hydrohalogenation: Alkene + HX (ex:HBr): |
regiochem: none, flat carbocation (rearrangement possible) stereochem:trans / Markovnikov what it does: replaces double bond with one H on less subs C and X on more subs C pdts: One X and one H, trans mec: 1-make DB attack H, give X its e- - add H to C with more H's,creates carbocation (could rearrange) 2- make X attack carbocat, 3-add X to more subs C 4-check pdts for enantiomer or not |
|
|
Halogenation: Alkene + X2 (ex: Br2): regiochem stereochem what it does / pdts mec: |
regiochem:none, but nuc attacks more substituted carbon stereochem: Markov Anti-addtn, trans products pdts: 2 trans Xs what it does: replaces double bond with anti (trans) halides on both sides of the bond mec: 1-make double bond attack one halide (remember to return e- to other halide), make halide ‘bite back’ 2-create a 3-side ring with two sides of what was the double bond and one halide 3-the other halide, now negative, backside attacks and opens rings reagents: X2 (Br2, Cl2) |
|
|
Halogenation: Alkene + X2 (ex: Br2):: regiochem stereochem what it does / pdts mec: |
products: alkane with 2 trans X |
|
|
Halohydrins: Alkene + X2 / H2O (ex: Br2/H2O) regiochem stereochem what it does / pdts mec: |
regiochem: ***remember to attack the more substituted carbon stereochem: Markonikov (trans) pdts: trans X / OH what it does: A halohydrin is an alcohol with a halogen on the adjacent carbon atom. In the presence of water, halogens add to alkenes to form halohydrins. mec:-The electrophilic halogen adds to the alkene to give a halonium ion, which is also electrophilic. -Water acts as a nucleophile to open the halonium ion and form the halohydrin. |
|
|
Free-Radical Addition of HBr: with ROOR (peroxide) Anti-Markovnikov Addition |
regiochem: none stereochem: Peroxide (ROOR) = anti-Markovnikov pdts : generate Halogen with an H and X inverted what it does-.Generates free radicals, can react with Br. or R-O. radicals mec: -Intermediate reacts with HBr to give the anti-Markovnikov product, in which H has added to the more substituted end of the double bond: the end that started with fewer hydrogens. |
|
|
Acid-Catalyzed Hydration of an Alkene: H2O / H2SO4 (cat) |
stereochem: none , carbocation (rearrangement possible) regiochem: Markov/ trans pdts: OH and H what it does: -Hydration of an alkene is the reverse of the dehydration of alcohols reagents: Alkene + acid H2O / (H2SO4, or H3O+, or H+) |
|
|
Oxymercuration–Demercuration: 1.Hg(OAc)2, H2O / 2. NaBH4 |
stereochem: anti add (trans) regiochem: Markovnikov/ trans pdts: 1. ring to Hg , 2.OH, H trans what it does: -Involves an electrophilic attack on the double bond by the positively charged mercury species. -The product is a mercurinium ion, an organometallic cation containing a three-membered ring .-In the second step, water from the solvent attacks the mercurinium ion to give (after deprotonation) an organomercurial alcohol. -A subsequent reaction is demercuration, to remove the mercury. Sodium borohydride( NaBH4, a reducing agent) replaces the mercuric acetate fragment with a hydrogenatom. |
|
|
Alkoxymercuration–Demercuration: 1.Hg(OAc)2, ROH / 2. NaBH4 |
stereochem: anti add (trans) regiochem: Markovnikov/ trans pdts: 1. ring to Hg , 2.OR, H trans what it does: an alkene reacts to form a mercurinium ion that is attacked by thenucleophilic solvent. Attack by an alcohol solvent gives an organomercurial ether thatcan be reduced to the ether. |
|
|
Hydroboration of Alkenes: 1. BH3, THF / 2. H2O2, NaOH |
regiochem: cis (syn-addt) no shift stereochem: anti-Markovnikov pdts: OH, H inverted mec: Converts alkenes to alcohols by adding water across the double bond, with anti-Markovnikov orientation. |
|
|
Acid-Catalyzed Opening of Epoxides (R (=O)-O-OH) / H3O+ |
regiochem: Nuc: H2O, attacks the more substituted C stereochem: Markovnikov, anti-add (trans) pdts: two OH added to the broken double bond what it does: Opens the double bond and one OH to each side, trans! |
|
|
Syn Dihydroxylation of Alkenes OsO4 ,H2O2 (or) KMnO4, OH |
regiochem: Nuc: H2O, attacks the more substituted C stereochem: syn addtn (cis) pdts: two OH added to the broken double bond on cys orienation what it does: Opens the double bond and one OH to each side but cis! |
|
|
Oxidative Cleavage of Alkenes 1. O3 / 2. (CH3)2 S (DMS) |
Problem-solving Hint: To predict the products from ozonolysis of an alkene, erase thedouble bond and add two oxygen atoms as carbonyl (C=O) groups where the double bond used to be. |
|
|
Catalytic Hydrogenation H2 / (Pd, Pt, Ni) cat |
regiochem: none stereochem: syn addt’n (pdts are cis) add: H2 catalyst: Pd, Pt, Ni what it does: removes double bond and adds H to both sides of it |
