Organic Chemistry

Question 1

Delta H = change in enthalpy

smaller enthaply =

Answer 1

smaller enthalpy= more stable.

more stable molecules need more energy to break its bond

Question 2

Single bond = easiest bond to break
| |
Triple Bond = hardest to break

Answer 2

Single bond requires the least amount of energy to break

Triple bond requires the greatest amount of energy to break the bond.

Question 3

CIS molecules ( Z) ( cyclic and alkenes) structures are polar or nonpolar ?

Answer 3

polar molecules

ODD number rings must always be polar when 2 substrates are attached.

Question 4

Trans molecules ( E) molecules are polar or nonpolar

Answer 4

nonpolar

Question 5

Pure alcohol has what kind of bonding

Answer 5

All Hydrogen bonding

when it is disturbed with any other compound, hydrogen bonding DECREASES

Question 6

weight and hydrogen bonding affects what ?

Answer 6

Boiling temperature of a liquid

Question 7

Enantiomer has how many chiral centers?

Answer 7

1

Question 8

Diasteromers

Answer 8

have 2+ chiral centers

Question 9

What are the types of isomers

Answer 9

• constitutional - break into new molecule
• conformational - rotate about a single bond
• configurational = can be cis/trans and optical ( diasteromers and enantiomers)

Question 10

what can enatiomers do with light?

Answer 10

rotate light (+) = dexi 
rotate light (-) = levi 

can only function in chiral enviroments?

Question 11

When there are lone pairs on an atom, what happens to its bond angle

Answer 11

it decreases due to the electron replusion occuring , VESPR theroy because electrons take more space.

Question 12

when a molecule can no longer undergo resonance and has distorted bond angles, what happens to that bond between the molecules?

Answer 12

the bond is weakened and can be easily broken.

Question 13

Lithium aluminum hydride has what as its intermediate

Answer 13

an aldehyde!!

Question 14

a Beta keto acid releases what when it is heated

Answer 14

a beta- ketoacid gets decarbozylated and loses the CO2 and it makes the amino acid into an amine.

Question 15

Boiling point increases with what?

Answer 15

it increases with MW, length and increased hydrogen bonding

Question 16

Strongest bond leads to the strongest boiling point

name the types of bond from strongest to weakest

Answer 16

1. Ionic
2. Hydrogen Bond
3. Dipole-dipole
4. Dispersion ( ie occurs with noble gases)

Question 17

Degree of saturation

Answer 17

[(2n+2)-x)/2)

n=number of carbon
x=number of hydrogen

Question 18

Benedict test

Answer 18

a chemical assay that detects carbonyl unit of sugar and it recognizes a hemiacetal.

Question 19

What are the reagents of the strecker synthesis

Answer 19

aldehyde, ammonium chloride ( NH4Cl) potassium cyanide(KCN)

Question 20

What is the strecker synthesis used for?

Answer 20

• 2 step process to make amino acids

1. amino nitrile formation
2. protonation of aminonitrale
3. attack by water to turn the nitrile into carboxylic acid

Question 21

Gabriel ( Malonic ester) synthesis reagents

Answer 21

potassium phthalimide, diethyl bromomalonate

Question 22

relative configuration is retained if what?

Answer 22

bonds of the sterocenter are not broken. position of groups around chiral center are maintained.

Question 23

absolute configuration measures…

Answer 23

R /S

Question 24

Stronger acid leads to a what kind of base

Answer 24

negligible base

Question 25

strong base leads to what kind of acid

Answer 25

negligible acid

Question 26

Name the 7 strong acids

Answer 26

- HCl - HBr - HI - H2SO4 - H3PO4 - HNO3 - HClO4

Question 27

Specific rotation = observed rotation/(concentration of solution X length of tube)

Answer 27

if volumetric changes of solution, there will be a decrease of observed rotation and decrease concentration of solution.

Question 28

meso compounds

Answer 28

by definition are achiral but they do contain chiral carbons , have symmetry, and do not rotate polarized light

Question 29

conformational isomer

Answer 29

conformational isomers are mainly when you look down a C-C bond . think newtons projection.

Question 30

configurational isomer

Answer 30

rotate around a single bond .

Question 31

Diasteriomers can be seperated by chemical or physical separation

Answer 31

so in passage, if it talks about crystallzation as a means to seperate 2 compunds, it is definitely a diasterimer!

Question 32

Diasteriomers can be seperated by chemical or physical separation

Answer 32

so in passage, if it talks about crystallzation as a means to seperate 2 compunds, it is definitely a diasterimer!

Question 33

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.

Answer 33

it basically means that there is no inversion of the molecules.

Question 34

define stereoselective

Answer 34

when a certain sterisisomer or a set of steroisomers predominiate as products

Question 35

define sterospecific

Answer 35

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.

Question 36

anomer = only have 1 opposite configuration at 1 carbon

Answer 36

Enantiomer - differ at all chiral carons

Question 37

Racemization - occurs when substitution occurs at a chiral center

Answer 37

sp2 can not undergo racemization because it is not a chiral center

Question 38

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

Answer 38

when you see lots of oxygen - think oxidizing when yoif you want to see lots of Hydrogens - think reducing

Question 39

if you want to isolate a molecule what types of isolating mechanisms can you use?

Answer 39

- Affinity Chromatography - size exclusion chromatography - Ion-exchnage chromatography

Question 40

Identify molecule - which methods can you use ?

Answer 40

- NMR - Isoelectric focusing - IR

Question 41

if you have a product with decreased melting point, that means you have impurity . here is why:

Answer 41

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.

Question 42

if something is aromatic, it should statisify 2 rules

Answer 42

1. overlapping p orbitals | 2. electrons must follow huckel's rule such that 4n+2