Term
| ways to synthesize ethers |
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Definition
williams
alkoxy mercuration/reduction
(alcohol dehydration and alkene addition--not talk about in class-require strong acid and heat and 2 primary alcohols-symmetrical ethers, unsym ethers--3', dilute strong acid) |
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Term
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Definition
alcohol----- ether
alcohol + strong base (with THF) yields strong nuc and primary (or methyl) halide
Sn2 to create ether
-tertiary, secondary alkyl halides can not be used (formed) |
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Term
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Definition
alkene------ether
alkene (alcohol solvent) 1. Hg(OAc) (racemic) 2. NaBH4, HO- form racemic mixture |
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Term
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Definition
stable to strong bases and nuc
reactive to strong acids
Sn2, Sn1, E1 |
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Term
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Definition
halohydrin cyclization
Direct epoxidation |
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Term
direct epoxidation
(alkene oxidation by peracids) |
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Definition
peracid + benzene (any alkene)----epoxide
concerted syn addition
5 arrows |
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Term
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Definition
1. alkene + Br2 (in H20)
2. Base (H0- or pyridine)
ANTI (backside attack) |
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Term
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Definition
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Term
| Sharpless Asymmetric Epoxidation |
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Definition
| (uses +OOH, Ti (cat)) yield extremely selective eposide |
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Term
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Definition
1. epoxide hydrolysis
2. osmylation of alkenes
3. catalytic osmylation |
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Term
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Definition
| epoxide +H2O, H+ yield racemic glycol |
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Term
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Definition
OsO4 + alkene---osmate ester--)+H20---glycol (+detox)
concerted syn addition |
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Term
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Definition
| alkene + OsO4 + TMAO in pyrimidine and H20---glycol |
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Term
glycol cleavage rxn
oxidation |
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Definition
| Glycol + H5IO6---intermediate cyclic per-iodate ester----aldehydes and ketones |
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Term
| nuc sub of epoxides under BASIC conditions |
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Definition
1. nuc sub
2. proton transfer
unsymmetric epoxides nuc react at least sub alkyl groups
inversion of config |
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Term
| nuc sub of epoxides under ACIDIC conditions |
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Definition
react with most sub alkyl group of epoxide 3'
2',1' give mixtures
inversion of configuration
if H20 is used as nuc product is glycol |
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Term
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Definition
| stretching and bending of bonds |
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Term
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Definition
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Term
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Definition
emmergent/incident light
I/I0 |
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Term
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Definition
1. bond stretching costs more E than bonding (higher f)
2. longer bonds (to heavier atoms) vibrate more easily than shorter bonds (to lighter atoms) (lower f)
3. single bonds vibrate more easily than multiple bonds (lower f) |
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Term
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Definition
must be a change in dipole moment
symmetrical not see IR |
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Term
| Region 3600 cm-1 - 1600 cm-1 (left side of IR) |
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Definition
highest E
most stretching
diagnostic characteristic |
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Term
| 1600cm-1- 600 cm-1 (right side of IR) |
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Definition
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Term
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Definition
mw
m---m+ (parent ion) use m/z for mw----fragmentation---- ch3+---ch2+ |
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Term
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Definition
gentler technique
M+ CH4+---H+----[M-H]+ = CH3 radical |
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Term
| for a compound having n carbons in ms |
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Definition
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Term
| if odd number of N atoms, molecular weight will be |
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Definition
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Term
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Definition
genetle
all parent ions present
spray mist of droplets, evap, gas phase ions |
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Term
| ms frag patterns: alkenes |
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Definition
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Term
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Definition
| inductive cleavage, 2 pathways |
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Term
| ms frag patterns: alcohols and ethers: alpha cleavage |
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Definition
| frag odd mass (even m/z m+) |
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Term
| ms frag patterns: primary alcohol 2 bond fragmentation |
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Definition
exception
even m+, EVEN mass fragment |
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Term
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Definition
nuc spin states
HextXhX gyromagnetic ratio
hv = resonant frequency |
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Term
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Definition
Hext + Hinduced + Hnearby nuc
Hnet |
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Term
| chemical shift Si (in ppm)= |
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Definition
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Term
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Definition
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Term
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Definition
| same chem shift in achiral/racemic medium but may be different in chiral medium |
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Term
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Definition
| may have different chem shifts in any medium |
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Term
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Definition
decreased local mag field by circulation of nearby e-
decreased e-neg--increased shielding
magnetic field of less shielded higher |
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Term
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Definition
increase local field at protons
decrease shielding protons
increase proton chem shift |
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Term
| increase in chem shift due to (3) |
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Definition
increased e-neg
increased # e-neg groups
decreased distance of e-neg groups |
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Term
| when change in chemical shift is greater than J (constant) |
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Definition
n adjacent H give rise to n+1 multiplet
relative intensities are predicted by pascals triangle |
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Term
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Definition
Highest with H on same carbon (10-20 Hz)
and if double bond-trans |
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Term
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Definition
| alcohol, too rapid chem equil |
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Term
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Definition
fourier transform technique
-excite all 13C at once
-collect data (intensities over time)
-can transform data into intensities vs frequency
-Bc integrated peak areas are unreliable
-13C has a broad chem shift range
-watch for symmetry |
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Term
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Definition
two pi bonds
good lewis bases |
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Term
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Definition
HBR
H20
Hydroboration oxidation rxn |
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Term
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Definition
HBR
H20
Hydroboration oxidation rxn |
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Term
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Definition
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Term
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Definition
with Hg+1, H2SO4
enol- ketone
acid (2 steps)
base (1 step) |
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Term
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Definition
give mixture of ketones
H20, hydroboration |
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Term
| Hydroboration oxidation of alkynes |
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Definition
disamyl borane
concerted cyn additon
antimarkovinikov
enol--- aldeyhyde |
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Term
| alkyne reduction reactions |
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Definition
1. hydrogenation
2. lindars
3. Na metal in liquid NH3 reduction |
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Term
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Definition
goes all the way to alkane
unless poisoned by Pb(OAc)2 and with CaCO3 (lindlars) to create CIS alkene only |
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Term
| Na Metal in liquid NH3 reduction of an akyne |
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Definition
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Term
| Substitution reaction of alkynes |
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Definition
Need strong base
NaNH2, LDA, R-MgX
electrophiles:
alkyl halide
toluide
good for extending C networds |
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