Organic Chemistry Flashcards
Delta H = change in enthalpy
smaller enthaply =
smaller enthalpy= more stable.
more stable molecules need more energy to break its bond
Single bond = easiest bond to break
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Triple Bond = hardest to break
Single bond requires the least amount of energy to break
Triple bond requires the greatest amount of energy to break the bond.
CIS molecules ( Z) ( cyclic and alkenes) structures are polar or nonpolar ?
polar molecules
ODD number rings must always be polar when 2 substrates are attached.
Trans molecules ( E) molecules are polar or nonpolar
nonpolar
Pure alcohol has what kind of bonding
All Hydrogen bonding
when it is disturbed with any other compound, hydrogen bonding DECREASES
weight and hydrogen bonding affects what ?
Boiling temperature of a liquid
Enantiomer has how many chiral centers?
1
Diasteromers
have 2+ chiral centers
What are the types of isomers
- constitutional - break into new molecule
- conformational - rotate about a single bond
- configurational = can be cis/trans and optical ( diasteromers and enantiomers)
what can enatiomers do with light?
rotate light (+) = dexi rotate light (-) = levi
can only function in chiral enviroments?
When there are lone pairs on an atom, what happens to its bond angle
it decreases due to the electron replusion occuring , VESPR theroy because electrons take more space.
when a molecule can no longer undergo resonance and has distorted bond angles, what happens to that bond between the molecules?
the bond is weakened and can be easily broken.
Lithium aluminum hydride has what as its intermediate
an aldehyde!!
a Beta keto acid releases what when it is heated
a beta- ketoacid gets decarbozylated and loses the CO2 and it makes the amino acid into an amine.
Boiling point increases with what?
it increases with MW, length and increased hydrogen bonding
Strongest bond leads to the strongest boiling point
name the types of bond from strongest to weakest
- Ionic
- Hydrogen Bond
- Dipole-dipole
- Dispersion ( ie occurs with noble gases)
Degree of saturation
[(2n+2)-x)/2)
n=number of carbon
x=number of hydrogen
Benedict test
a chemical assay that detects carbonyl unit of sugar and it recognizes a hemiacetal.
What are the reagents of the strecker synthesis
aldehyde, ammonium chloride ( NH4Cl) potassium cyanide(KCN)
What is the strecker synthesis used for?
- 2 step process to make amino acids
- amino nitrile formation
- protonation of aminonitrale
- attack by water to turn the nitrile into carboxylic acid
Gabriel ( Malonic ester) synthesis reagents
potassium phthalimide, diethyl bromomalonate
relative configuration is retained if what?
bonds of the sterocenter are not broken. position of groups around chiral center are maintained.
absolute configuration measures…
R /S
Stronger acid leads to a what kind of base
negligible base
strong base leads to what kind of acid
negligible acid
Name the 7 strong acids
- HCl
- HBr
- HI
- H2SO4
- H3PO4
- HNO3
- HClO4
Specific rotation = observed rotation/(concentration of solution X length of tube)
if volumetric changes of solution, there will be a decrease of observed rotation and decrease concentration of solution.
meso compounds
by definition are achiral but they do contain chiral carbons , have symmetry, and do not rotate polarized light
conformational isomer
conformational isomers are mainly when you look down a C-C bond . think newtons projection.
configurational isomer
rotate around a single bond .
Diasteriomers can be seperated by chemical or physical separation
so in passage, if it talks about crystallzation as a means to seperate 2 compunds, it is definitely a diasterimer!
Diasteriomers can be seperated by chemical or physical separation
so in passage, if it talks about crystallzation as a means to seperate 2 compunds, it is definitely a diasterimer!
if a problem states that the configuration is retained, it does not mean that the absolute configuration is retained, the relative can be as well.
it basically means that there is no inversion of the molecules.
define stereoselective
when a certain sterisisomer or a set of steroisomers predominiate as products
define sterospecific
a reaction is sterospecific if different isomers lead to isomerically opposite products.
any reaction that is sterospecific is also stereoselctive but the converse it not true.
anomer = only have 1 opposite configuration at 1 carbon
Enantiomer - differ at all chiral carons
Racemization - occurs when substitution occurs at a chiral center
sp2 can not undergo racemization because it is not a chiral center
PCC is a weak oxidier and it will only stop alcohol to aldehyde
chromic acid is a stronger oxiziging agent and will take alcohol to carboxlic acid -> only 1* and 2*
3* will not under go oxdiation
when you see lots of oxygen - think oxidizing
when yoif you want to see lots of Hydrogens - think reducing
if you want to isolate a molecule what types of isolating mechanisms can you use?
- Affinity Chromatography
- size exclusion chromatography
- Ion-exchnage chromatography
Identify molecule - which methods can you use ?
- NMR
- Isoelectric focusing
- IR
if you have a product with decreased melting point, that means you have impurity . here is why:
if you have impurity, it will get in the way of the bonds forming which will leaded to a messed up crytal forming rather than pure. Pure srtyal will have a higher melting point ( similar to that found in literature)
if the crystal has a higher melting point that the one in literature, you probably have the wrong crystal.
if something is aromatic, it should statisify 2 rules
- overlapping p orbitals
2. electrons must follow huckel’s rule such that 4n+2
