ochem 2 importants

Question 1

Infrared spectroscopy is used to determine different functional groups by measuring _______ of the molecule

Answer 1

molecular vibrations
- stretching and bending

Question 2

Where is the magic line for IR?

Answer 2

3000 cm-1

Question 3

For a molecule to be IR active, vibrations must change the overall _______ of the molecule

Answer 3

dipole moment

Question 4

for IR, stronger bonds absorb at _______ frequencies, and Conjugation will ______ the frequency

Answer 4

higher
lower

Question 5

know the approximate frequencies of all the important functional groups in IR

Answer 5

…

Question 6

MS measures the _______ which can be used to determine the molecular formula

Answer 6

molecular weight

Question 7

MS requires fragmentation, which is destructive, and forms a _______ and a _______

Answer 7

cation and radical

Question 8

MS only detects _______ fragments

Answer 8

positively charged
- no radicals

Question 9

In MS, the furthest right peak is labeled the _______ while the tallest peak in the spectrum _______

Answer 9

parent ion [M+]
base ion

Question 10

important isotope ratios for the parent ion:
1) C _____:_____
2) Cl _____:_____
3) Br _____:_____

Answer 10

1) 100:1
- M and M+1
2) 3:1
- M and M+2
3) 1:1
- M and M+2

Question 11

What are the 3 possibilities for electron loss in MS? (in order from easiest to hardest)

Answer 11

1) NB
2) π
3) σ

Question 12

MS fragmentation patterns:
1) type 1: radical cation loses small, neutral molecule (_______)
2) Type 2: the bond in the radical cation where the electron was lost breaks to give 2 molecules: _______ and _______
3) type 3: homolytic cleavage yielding 2 molecules with radical (often _____)

Answer 12

1) H2O
2) radical and cation
- look for C+ and radical stability
- resonance always stablizes
3) α
- all carbonyl groups undergo alpha cleavage

check slide 58 (12-15) for McLafferty rearr

Question 13

When interpreting H1NMR, what are the 3 things that you need to look out for?

Answer 13

1) Chemical shift
2) integration
3) splitting

Question 14

Study chemical shift quizlet

Answer 14

lol

Question 15

of signals:
What is the difference between homeotopic, enantiotopic, and diastereotopic signals on H1NMR

Answer 15

homeotopic: # of dif type of H
- symmetry
enantiotopic: electronically eq, but chemically distinct (single peak)
diastereotopic: electronically and chemically distinct (2 peaks)
- look for chiral center on OG molecule for diastereotopic

Question 16

What is the rule for H1 NMR integration?

Answer 16

Relative height of integral
- proportions of H contributing to peak

Question 17

What is the rule for H1 NMR splitting?

Answer 17

N+1 rule of neighboring H’s
- Hydrogen bonding doesn’t contribute

Question 18

leaning doublets leads is interpreted as _______ and multiplets are interepred as _______

Answer 18

para-substituted aromatic rings
monosubstiuted ar ring

Question 19

doublet of doublets are interpreted as _______

Answer 19

monosubstiuted alkene

Question 20

Carbon-13 NMR is most useful for determining _______

Answer 20

of different Cs

Question 21

explain Carbon-13 NMR splitting

Answer 21

(number of H’s attached to that specific C) + 1

Question 22

1) 13C NMR shows _______ carbon types
2) DEPT-90: shows signals for ______ only
3) DEPT-135: _______ shows negative and _______ shows positive

Answer 22

1) all
2) CH
3) CH2; CH and CH3

Question 23

UV-vis is used to determine the amount of _______ in a molecule. The energy measured is correlated to _______

Answer 23

conjugation
electronic transitions

Question 24

Conjugated systems have electronic transitions with lower energies = wavelengths _______ than 200 nm

Answer 24

longer
High E = Low λ

Question 25

What is beer's law regarding absorbance?

Answer 25

A = ε c l

Question 26

Rules for drawing UV-vis orbital diagrams: 1) # of π bonds = # of _______ π MO's 2) there are equal and oppposite _______ MO's 3) any _______ on a conjugated carbonyl are placed in a _______ orbital at E=0 4) fill in electrons and label MO's

Answer 26

1) bonding 2) anti-bonding 3) lone pairs; NB

Question 27

Rules for MO theory: 1) As the number of nodes increases, the energy of the MO ________ 2) What is the rule for the number of nodes? 3) _____ # of MO's may have a line through a p-orbital

Answer 27

1) increases 2) N-1 rule 3) odd

Question 28

1,2 addition to a butadiene is named the _______ product while 1,4 addition is named the _______ product

Answer 28

kinetic thermodynamic

Question 29

The diels-alder reaction involves the [4+2] cyloaddition that forms a ___-membered ring with stereochemical control. USES _______ conditions not _______ conditions

Answer 29

6 thermal; photochemical

Question 30

Rules for creating MO diagrams for cyclic, conjugated molecules: 1) # of orbitals = number of _______ in the ring 2) place _____ orbital at lowest energy then others in _______ at the same energy until they run out 3) Make sure the orbitals are _______ distributed

Answer 30

1) atoms 2) 1; pairs (degenerate orbitals) 3) symmetrically (16-3,4)

Question 31

What are the 3 rules that make a ring aromatic or antiaromatic?

Answer 31

1) cyclic 2) fully conjugated 3) planar

Question 32

Explain Huckel's rule regarding aromaticity

Answer 32

4N + 2 = aromatic 4N = anti-aromatic

Question 33

For chapter 17, just study the reagents for aromatic compounds

Answer 33

yes

Question 34

Explain how sterics and induction affect reactivity of aldehydes and ketones

Answer 34

sterics lowers reactivity induction (EWG) destablize partial positive and make carbonyl more reactive

Question 35

What are the steps to basic hydration? What are the steps to acidic hydration?

Answer 35

1) attack 2) protonate 1) protonate 2) attack 3) deprotonate

Question 36

in many cases, enantiomers of nitrogens cannot be isolated because of nitrogen inversion, What are the 3 cases where chiral amines can be resolved?

Answer 36

1) Presence of chiral carbons 2) quaternary salt with 4 different groups 3) in a small ring (3C or 4C) that's not meso

Question 37

Amines are strongly _____ and as such they can abstract a proton from water. they behave as a _______ with an eletrophile and a _______ by accepting a proton from a proton acid

Answer 37

1) basic 2) nucleophile (lewis base) 3) bronsted-lowry base

Question 38

study diazonium salts quizlet

Answer 38

...

Question 39

Reacting an imine with any type of reducing agent will result in the formation of an _______

Answer 39

amine 1° and 2° form normal 3° happens in one step and can only be done using NaBH(OAc)3, CH3COOH