Chem2 - Intro to Orgo

Question 1

how do you calculate formal charge?

Answer 1

of valence electrons-(#nonbonded electrons+# of bonds)

Question 2

characteristics of a sigma bond?

Answer 2

low energy, stable, electrons localized between points of positive charge

Question 3

characteristics of a pi bond?

Answer 3

shortens bond length, increases entropy, introduces rigidity, forms double and triple bonds (above and below sigma bond)

Question 4

how do you calculate hybridization?

Answer 4

count number of lone pairs and sigma bonds, subtract 1

Question 5

sp geometry?

Answer 5

180 and linear

Question 6

sp2 geometry?

Answer 6

120 and trigonal planar

Question 7

sp3 geometry?

Answer 7

109.5 and tetrahedral or bent

Question 8

what makes a cyclic compound aromatic?

Answer 8

must have 4n+2 pi electrons to be aromatic, and conjugated

Question 9

nucleophilic fxnl group

Answer 9

negative charge, ATTACKS

Question 10

electrophilic fxnl group

Answer 10

+ charge and GETS ATTACKED

Question 11

ether?

Answer 11

R-O-R’

Question 12

amine?

Answer 12

NH2-R,can also be secondary or tertiary

Question 13

ester?

Answer 13

R-COO-R

Question 14

amide?

Answer 14

R-CONH2

Question 15

what is a structural isomer

Answer 15

same formula, different connectivity

Question 16

what is a conformational isomer

Answer 16

same connectivity, different spatial orientation

Question 17

what is a stereoisomer

Answer 17

2 UNIQUE molecules, same formula, and connectivity

Question 18

what is an entantiomer?

Answer 18

non superimposable mirror immage, differs at every single chiral carbon

Question 19

what is a diastereomer?

Answer 19

don’t differ at ALL chiral carbons, therefore not mirror images

Question 20

what is absolute configuration?

Answer 20

R or S?

Question 21

what is relative configuration?

Answer 21

when 1 substituent changes, and others remain the same spatially

Question 22

what is an epimer?

Answer 22

refers to one pair of stereocenters that differ at only one chiral center

Question 23

what is an anomer?

Answer 23

a cyclic diastereomer, the chiral carbon is called the anomeric carbon

Question 24

what is the E/Z system?

Answer 24

given the double bond shit, if the highest priority groups are on the same side then they are Z, otherwise they are E

Question 25

what does dichloromethane solvate?

Answer 25

nonpolar solutes

Question 26

what is the purpose of benedict's test?

Answer 26

to detect reducing sugars

Question 27

glucose forms a ___ ring

Answer 27

pyranose

Question 28

fructose forms a ___ ring

Answer 28

furanose

Question 29

what functional group is represented by an IR peak at 1650?

Answer 29

alkenes

Question 30

what functional group is an IR peak at 1735?

Answer 30

carbonyl

Question 31

what are the steric requirements for a good protecting group?

Answer 31

LEAST sterically hindered is usually best

Question 32

in a trans cyclic molecule one substituent will be ___ and the other will be ____

Answer 32

axial, equatorial

Question 33

does the rate of an SN1 reaction depend on nucleophile concentration?

Answer 33

no

Question 34

what kind of light do conjugated systems absorb?

Answer 34

UV light

Question 35

what is an imide?

Answer 35

nitrogen attached to 2 ketones

Question 36

in NMR spec, high field/upfield means shielding or deshielding effect

Answer 36

shielding

Question 37

in NMR spec, low field/downfield means shielding or deshielding effect

Answer 37

deshielding

Question 38

what type of solvent is favored by SN1 rxns?

Answer 38

protic

Question 39

what type of solvent is preferred by sn2 rxns?

Answer 39

polar aprotic

Question 40

what is the IR range for the OH group in a carboxylic acid?

Answer 40

2500-3300

Question 41

NMR peaks between 5-8 represent

Answer 41

amide hydrogens

Question 42

what is a reducing sugar?

Answer 42

has a free aldehyde or ketone group. (all monosaccharides are reducing sugars)

Question 43

what compound elutes first in reverse phase high performance liquid chromatography?

Answer 43

the more polar compund

Question 44

how can you tell if a disaccharide is a reducing sugar?

Answer 44

if it is a hemiacetal (in equilibrium with open chain form that has an aldehyde or a ketone)

Question 45

are SN2 reactions affected by steric hindrance?

Answer 45

YES

Question 46

what is the first peak in a gas chromatograph representing?

Answer 46

the thing with the lowest molecular weight and weakest intermolecular forces

Question 47

for cyclic compounds, the most stable position is when

Answer 47

large groups are equatorial

Question 48

how do you calculate degrees of unsaturation?

Answer 48

(#Carbons*2)+2-# of hydrogens