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24 Cards in this Set
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hydrogenation of alkenes
alkene + H2(metal catalyst/ pt, pd,RH, ni-----> |
alkane
no Regiochemistry since adding two of same(h's) Stereochemistry: SYN addition( will get 2 enantiomers) but is also stereoselective by adding to less crowded face of double bond( when this happens you'll oly get one product) |
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electrophilic addition of hydrogen halides to alkenes :
alkene + HBr/ HCl -----> solvents: ChCl3, acetic acid, |
alkyl halide
Regiochemistry : Markovnikovs ( halogen on most subs C) watch for poss rearrangements with hydride or methyl shifts, protonatiion occurs in direction that forms most stable carbocation |
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free radical addition of HBr to alkenes
only used with hbr!!! alkene + Hbr with peroxides(ROOR)----> or alkene + Hbr with light with or with out peroxides---> |
anti markovnikov primary alkyl halide
Regiochemistry is anti markovnikov: br added to less substituted carbon |
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with addition mechanisms if you create a just 1 new stereo center you will get two products ( pair of enantiomers regardless if syn or anti addition)
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know
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hydration of alkenes using an acid catalyst
alkene to produce an alcohol ( this reaction is the opposite of our dehydration of alcohol beta elimination reaction alkene + H3o+\ H20------> or alkene + H2SO4/ H20----> |
alcohol
Regiochemistry : markovnikov poss rearrangements with methyl or hydride shifts |
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if we want to form the alkene starting from an alcohol we would use concentrated acid ( elim rxn)
if we start with alkene and want to from alcohol we need a diluted acid so that's why we have acid + h20 |
know
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hyrdoboration oxidation of alkenes :
alkene + BH3, THF/ H202, NaOh----> or alkene + B2H6(diglyme)/H202,OH- ----> |
forms an anti markovnikov alcohol
regiochem : anti mark oh grp ends up on least subst c stereochemistry: syn addition |
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synthesis techniques: substitution lets us
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change grps
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elimination reactions lets us form
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alkenes
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addition reaction lets us add two grps across double bond
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can turn into alcohols or alkyl halides
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if we have something that's changes positions from one car on to other easiest way is to eliminate then re add
1. for alkyl halides for elimination for zaitsevs product( most subs double bond use..... 2. for Hoffman product( least subt double bond) use... |
1. NaOet
2. t-buOK |
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for alcohols that you need to move to diff position of carbon need to eliminate first then add as well
if need to eliminate using Hoffman product( double bond forms to give least substituted double bond first change oh into good leaving group |
1. TsCl, pyridine( changes alcohol into Ots (toslate) which is better LG
2. then use strong steric ally hindered base to eliminate to Hoffman product( t-buOK) 3. then use addition to give anti mark or mark of alcohol |
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to eliminate alcohols to zaitsevs product use
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h2so4, heat
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when just start with alkane and need to form alkene and there are no functional grps on it only thing to do is radically brominate
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this will add br on most substituted carbon then from there you can eliminate to form double bond
use NBS, light |
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addition of halogens to alkenes
alkenes + br2----> (limited to br2 and cl2) |
forms a vicinal dihalide: two adjacent carbons with a halide on each...br added to pop sides of double bond which will form enantiomers
Regiochemistry : irrelevant due to same atoms stereochemistry : Anti addition bromonium ion formed in first step, then attacked back side due to bridged ion which explains anti addition |
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halohydrin formation
alkene + br2 and H2o---> |
alkene converted to vicinal halohydrin: br and oh grps
Regiochemistry OH on most subst C stereochemistry: Anti only product!!! |
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carboxylic acid
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RCdouble bond O OH
Cooh formula :RCO2H |
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peroxy acid
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RC double bond OOh
COOOH resembles carboxylic acids but has one more O formula :RCO3H |
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Epoxidation of alkenes
alkene + peroxyacid( RCO3H) solvents used: HClO4 HClO3 HClO2, HClO |
forms epoxide3membered ring that contains O (and a carboxylic acid (RCO2H)
stereoselectiveNess : syn addition |
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Ozonolysis
alkene + O3/ CH3)2S or O3/ Zn, H2o |
will completely cleave double bond forming either 2 aldehydes, 2 ketones, or one of each
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aldehyde
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RC double bond oH
or just think of it as c double bond oh only attached to one other C |
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ketone
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c double bond O attached to 2 C
this will be major product over aldehyde |
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for ozonolysis for each C double bond C we simply erase that bond and put 2 C double bond O in its place
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trick
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when you only show one product means symmetric on no sides of double bond if going from reverse in ozonolysis
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know
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