www.clutchprep.com ORGANIC - CLUTCH CH. 15 - ANALYTICAL TECHNIQUES: IR, NMR, MASS SPECT
! www.clutchprep.com
!
ORGANIC - CLUTCH
CH. 15 - ANALYTICAL TECHNIQUES: IR, NMR, MASS SPECT
CONCEPT: PURPOSE OF ANALYTICAL TECHNIQUES
Classical Methods (Wet Chemistry): Chemists needed to run dozens of chemical reactions to determine the type of
molecules in a compound.
EXAMPLE: Tollen’s Test
Instrumental Methods (Dry Chemistry): Expensive scientific instruments investigate the properties of molecules.
EXAMPLE: 1H NMR
ORGANIC - CLUTCH
CH. 15 - ANALYTICAL TECHNIQUES: IR, NMR, MASS SPECT
Page 2
CONCEPT: IR SPECTROSCOPY- GENERAL FEATURES
● IR Spectroscopy is a chemical analytical method that uses differing frequencies of infrared light to detect predictable
types of chemical bonds in molecules.
□ The frequencies will cause certain bonds to _________________
□ Stretching, Twisting, Wagging, Scissoring, etc.
□ If the molecule is symmetrical, e.g. N2, the band is not observed in the IR spectrum.
Major regions of absorption Common IR Ranges
3200 – 3600 -OH Strong, Broad
3300 -NH Peaks = H’s
SP3 = 2900 – 3000
SP2 = 3000 – 3150
SP = 3150 - 3300
-CH Choppy
2200-2300 C≡C
C≡N
Medium, Sharp
1700 C=O Very Strong, Sharp
1650 C=C Medium, Sharp
ORGANIC - CLUTCH
CH. 15 - ANALYTICAL TECHNIQUES: IR, NMR, MASS SPECT
Page 3
CONCEPT: IR SPECTROSCOPY- FREQUENCIES
● There are specific absorption frequencies in the functional group region that we should be familiar with
EXAMPLE: What are the major IR absorptions for each compounds?
ORGANIC - CLUTCH
CH. 15 - ANALYTICAL TECHNIQUES: IR, NMR, MASS SPECT
Page 4
PRACTICE: Answer each of the following questions based on the images below.
O
A
O
B
O
C
OH
H
D
OF3C O
CF3
E
a) Which compounds show an intense peak ~ 1700 cm-1?
b) Which compound shows an intense, broad peak at ~ 3400 cm-1?
c) Which compound has a peak at ~1700 cm-1, but no peaks at 2700 cm-1?
d) Which compound has no signal beyond the fingerprint region?
ORGANIC - CLUTCH
CH. 15 - ANALYTICAL TECHNIQUES: IR, NMR, MASS SPECT
Page 5
PRACTICE: The following compound contains two carbonyl groups. Identify which carbonyl group will exhibit a signal at a lower wavenumber.
O
O
ORGANIC - CLUTCH
CH. 15 - ANALYTICAL TECHNIQUES: IR, NMR, MASS SPECT
Page 6
CONCEPT: IR SPECTROSCOPY- DRAWING HYDROCARBONS
Alkanes:
Alkenes:
Terminal Alkynes:
ORGANIC - CLUTCH
CH. 15 - ANALYTICAL TECHNIQUES: IR, NMR, MASS SPECT
Page 7
CONCEPT: IR SPECTROSCOPY- DRAWING ALCOHOLS AND AMINES
Alcohols:
1° Amines:
2° Amines:
ORGANIC - CLUTCH
CH. 15 - ANALYTICAL TECHNIQUES: IR, NMR, MASS SPECT
Page 8
CONCEPT: IR SPECTROSCOPY- DRAWING SIMPLE CARBONYLS
Ketones:
Esters:
ORGANIC - CLUTCH
CH. 15 - ANALYTICAL TECHNIQUES: IR, NMR, MASS SPECT
Page 9
CONCEPT: IR SPECTROSCOPY- DRAWING COMPLEX CARBONYLS
Aldehydes:
Carboxylic Acids:
ORGANIC - CLUTCH
CH. 15 - ANALYTICAL TECHNIQUES: IR, NMR, MASS SPECT
Page 10
CONCEPT: IR SPECTROSCOPY- DRAWING CONCEALED FUNCTIONAL GROUPS
Alkyl Haldies: Ethers: 3° Amines:
ORGANIC - CLUTCH
CH. 15 - ANALYTICAL TECHNIQUES: IR, NMR, MASS SPECT
Page 11
PRACTICE: Based on IR data given determine the structure of the unknown. Unknown compound A has molecular formula C4H11N. It shows a peak at 2900 cm-1 and peaks in the fingerprint region.
PRACTICE: Based on IR data given determine the structure of the unknown. Unknown compound B has molecular formula C4H11N. It shows a single peak at approximately 3400 cm-1 as well as peaks at 2900 cm-1 and in the fingerprint region. Compound B also possesses a branched alkyl group.
PRACTICE: Based on IR data given determine the structure of the unknown. Unknown compound C has molecular formula C6H10O3. It shows peaks at 2900, 1850 , 1740 cm-1 and in the fingerprint region.
ORGANIC - CLUTCH
CH. 15 - ANALYTICAL TECHNIQUES: IR, NMR, MASS SPECT
Page 12
PRACTICE: Match the following functional group choices with the supplied infrared spectra data
A) Ether B) Ketone C) Alcohol D) Alkene E) Nitrile
ORGANIC - CLUTCH
CH. 15 - ANALYTICAL TECHNIQUES: IR, NMR, MASS SPECT
Page 13
PRACTICE: Match the following functional group choices with the supplied infrared spectra data. A) Alkyl Halide B) Alkyne C) Carboxylic Acid D) Alkene E) Ketone
ORGANIC - CLUTCH
CH. 15 - ANALYTICAL TECHNIQUES: IR, NMR, MASS SPECT
Page 14
PRACTICE: Match the following functional group choices with the supplied infrared spectra data.
A) Aldehyde B) Alkane C) Carboxylic Acid D) Ester E) Ether PRACTICE: Match the following functional group choices with the supplied infrared spectra data. A) Ketone B) Alkyne C) Alkene D) Alkyl Halide E) Amine
ORGANIC - CLUTCH
CH. 15 - ANALYTICAL TECHNIQUES: IR, NMR, MASS SPECT
Page 15
CONCEPT: 1H NUCLEAR MAGNETIC RESONANCE- GENERAL FEATURES
1H (Proton) NMR is a powerful instrumental method that identifies protons in slightly different electronic environments by
inducing tiny magnetic fields in the electrons around the nucleus.
General Spectrum:
● ____________ is the standard reference point for NMR
● Electrons __________ protons from the effects of NMR
● The further downfield, the more __________ the proton
● There are 4 types of information we can gain from
NMR spectra.
Four Types of Information
1. Total Number of Signals
● Describes how many different types of hydrogens are present
2. Chemical Shift
● Describes how shielded or deshieldied the hydrogens are
3. Height of Signals (Integration)
● Describes the relative ratios of each type of hydrogen
4. Spin-Splitting (Multiplicity)
● Describes how close or far the different hydrogens are to each other
ORGANIC - CLUTCH
CH. 15 - ANALYTICAL TECHNIQUES: IR, NMR, MASS SPECT
Page 16
CONCEPT: 1H NMR – TOTAL NUMBER OF SIGNALS
There are as many signals on each spectrum as there are unique, non-equivalent protons.
● Equivalent protons are defined as protons that have the same prospective on the molecule
● For now, let’s assume that hydrogens bound to the __________ ________________ are equivalent
□ Symmetry will reduce the total number of signals
EXAMPLE: How many different types of protons (signals) are there on each molecule?
ORGANIC - CLUTCH
CH. 15 - ANALYTICAL TECHNIQUES: IR, NMR, MASS SPECT
Page 17
PRACTICE: How many types of electrically unique protons (peaks) are there in the following molecule?
PRACTICE: How many types of electrically unique protons (peaks) are there in the following molecule?
ORGANIC - CLUTCH
CH. 15 - ANALYTICAL TECHNIQUES: IR, NMR, MASS SPECT
Page 18
PRACTICE: How many types of electrically unique protons (peaks) are there in the following molecule?
PRACTICE: How many types of electrically unique protons (peaks) are there in the following molecule?
ORGANIC - CLUTCH
CH. 15 - ANALYTICAL TECHNIQUES: IR, NMR, MASS SPECT
Page 19
PRACTICE: How many types of electrically unique protons (peaks) are there in the following molecule?
PRACTICE: How many types of electrically unique protons (peaks) are there in the following molecule?
ORGANIC - CLUTCH
CH. 15 - ANALYTICAL TECHNIQUES: IR, NMR, MASS SPECT
Page 20
CONCEPT: 1H NMR – PROTON RELATIONSHIPS
Hydrogens attached to the same carbon actually do have different relationships based on their chirality.
□ The Q-Test is used to determine the specific type of chirality of each hydrogen.
a. Homotopic Protons
Q-Test DOES NOT yield new chiral center
● Protons are always homotopic and are considered ______________________ (They share a signal)
● In general, the three hydrogens on -CH3 groups will always be homotopic
b. Enantiotopic Protons
Q-Test DOES yield new chiral center
.
● No original chiral centers = protons are still _____________________________ (They share a signal)
c. Diastereotopic Protons
Q-Test DOES yield new chiral center
.
● 1+ original chiral centers = protons are now __________________________ (Each proton gets its own signal)
ORGANIC - CLUTCH
CH. 15 - ANALYTICAL TECHNIQUES: IR, NMR, MASS SPECT
Page 21
EXAMPLE: How many signals will each molecule possess in 1H NMR?
ORGANIC - CLUTCH
CH. 15 - ANALYTICAL TECHNIQUES: IR, NMR, MASS SPECT
Page 22
PRACTICE: Identify the indicated set of protons as unrelated, homotopic, enantiotopic, or diastereotopic.
PRACTICE: Identify the indicated set of protons as unrelated, homotopic, enantiotopic, or diastereotopic.
PRACTICE: Identify the indicated set of protons as unrelated, homotopic, enantiotopic, or diastereotopic.
ORGANIC - CLUTCH
CH. 15 - ANALYTICAL TECHNIQUES: IR, NMR, MASS SPECT
Page 23
CONCEPT: 1H NMR – PROTON RELATIONSHIPS
d. E / Z Diastereoisomerism
Q-Test DOES yield new trigonal center on terminal double bonds
● Protons are always diastereotopic and are ____________________________ (Each proton gets its own signal)
EXAMPLE: How many peaks will each molecule possess in 1H NMR?
ORGANIC - CLUTCH
CH. 15 - ANALYTICAL TECHNIQUES: IR, NMR, MASS SPECT
Page 24
CONCEPT: 1H NMR – CHEMICAL SHIFTS
The chemical shift indicates the exact electrochemical environment that each proton is experiencing.
● In general, electronegative groups will pull electrons away from nuclei, deshielding them
● Shifts increase (move downfield) as protons become more deshielded
C – H 1 – 2 C = C 4.5 – 6
C ≡ C 2.5 Benzene 6 – 8
Z – C – H 2 – 4 Aldehyde, -CHO 9-10
OH, NH 1 – 5 Carboxylic Acid , -COOH 10-13
Your professor will determine how many chemical shifts you should memorize. We’ll go over them just in case.
EXAMPLE: Order the following five protons from most deshielded to most shielded
ORGANIC - CLUTCH
CH. 15 - ANALYTICAL TECHNIQUES: IR, NMR, MASS SPECT
Page 25
PRACTICE: Which of the labeled protons absorbs energy most upfield in the 1H NMR?
O
HA
B
C
D
E
PRACTICE: Which of the labeled hydrogens will be most de-shielded?
O O
O
O O O
O
A B C D E
PRACTICE: Which compound possesses a hydrogen with the highest chemical shift for its 1H NMR signal?
A B C D
F F
F
F
F
F
ORGANIC - CLUTCH
CH. 15 - ANALYTICAL TECHNIQUES: IR, NMR, MASS SPECT
Page 26
CONCEPT: 1H NMR – SPIN-SPLITTING WITHOUT J-VALUES
Also known as spin-spin coupling, or J-coupling, this describes the distances between different protons.
Note: This topic can be taught with or without J-values. Check with your professor to determine how much detail you should learn. For now, we will start with the simplest explanation, (should suffice for 90% of professors), which is without J-values.
● Adjacent, _______ - ____________________ protons will split each other’s magnetic response to the NMR
□ We use the ______________ rule to determine how many splits we will achieve
□ Pascal’s Triangle predicts the shape of the splits we will get
EXAMPLE: How will the following protons be split?
ORGANIC - CLUTCH
CH. 15 - ANALYTICAL TECHNIQUES: IR, NMR, MASS SPECT
Page 27
PRACTICE: Predict the splitting pattern (multiplicity) for the following molecule:
PRACTICE: Predict the splitting pattern (multiplicity) for the following molecule:
ORGANIC - CLUTCH
CH. 15 - ANALYTICAL TECHNIQUES: IR, NMR, MASS SPECT
Page 28
PRACTICE: Which of the following compounds gives a 1H NMR spectrum consisting of only a singlet, a triplet, and a pentet?
a) CH3OCH2CH2CH2CH2OH
b) CH3OCH2CH2OCH2CH3
c) CH3OCH2CH2CH2OCH3
d) CH3OCH2CH2OCH3
ORGANIC - CLUTCH
CH. 15 - ANALYTICAL TECHNIQUES: IR, NMR, MASS SPECT
Page 29
CONCEPT: 1H NMR – SPIN-SPLITTING WITH J-VALUES AND TREE DIAGRAMS
Coupling-Constants, also known as J-values, describe the amount of interaction that a proton will have on another.
Here are some examples of common coupling-constants (measured in Hz):
‘
Pascal’s Triangle only helps to predict the shapes of splits when all of the J-values are assumed to be the same.
● When multiple J-values are involved, tree diagrams are needed to predict the shapes of the splits.
Drawing Simple Tree Diagrams:
First, let’s use tree diagrams to help us understand why Pascal’s Triangle and the n + 1 Rule make sense.
● Each split represents the J-value in Hz of a single proton. What does n + 1 predict here? ________________ ANSWER
ORGANIC - CLUTCH
CH. 15 - ANALYTICAL TECHNIQUES: IR, NMR, MASS SPECT
Page 30
CONCEPT: 1H NMR – SPIN-SPLITTING WITH J-VALUES AND TREE DIAGRAMS
Drawing Complex Tree Diagrams:
Now let’s use an example where multiple J-values are involved. Always split in order of highest to lowest values.
● Before starting, what does the n + 1 Rule predict here? ___________________ ANSWER
EXAMPLE: Use a tree diagram to predict the splitting pattern of the bolded proton.
ORGANIC - CLUTCH
CH. 15 - ANALYTICAL TECHNIQUES: IR, NMR, MASS SPECT
Page 31
PRACTICE: Draw a tree diagram for H* in the structure below.
F2CH*CH(CH3)2 JH*-F = 50 Hz JH*-H = 7 Hz
ORGANIC - CLUTCH
CH. 15 - ANALYTICAL TECHNIQUES: IR, NMR, MASS SPECT
Page 32
CONCEPT: 1H NMR SPIN-SPLITTING – COMMON PATTERNS
Some splitting patterns are highly indicative of certain structures. We can get ahead by memorizing them.
EXAMPLE: Which common 1H NMR splitting pattern seen below could help us determine the molecular structure?
ORGANIC - CLUTCH
CH. 15 - ANALYTICAL TECHNIQUES: IR, NMR, MASS SPECT
Page 33
CONCEPT: 1H NMR – INTEGRATION
Integration describes how many of each type of hydrogen are present, expressing this information as relative ratios.
● Uses the Area Under the Curve (AUC) to visually demonstrate which hydrogens are most prevalent.
EXAMPLE: Draw the complete NMR spectrum:
ORGANIC - CLUTCH
CH. 15 - ANALYTICAL TECHNIQUES: IR, NMR, MASS SPECT
Page 34
PRACTICE: Which of the following molecules gives a 1H NMR spectrum consisting of three peaks with integral ratio of 3:1:6?
ORGANIC - CLUTCH
CH. 15 - ANALYTICAL TECHNIQUES: IR, NMR, MASS SPECT
Page 35
PRACTICE: Draw the approximate positions that the following compound might show in its 1H NMR absorptions?
ORGANIC - CLUTCH
CH. 15 - ANALYTICAL TECHNIQUES: IR, NMR, MASS SPECT
Page 36
PRACTICE: Draw the approximate positions that the following compound might show in its 1H NMR absorptions?
ORGANIC - CLUTCH
CH. 15 - ANALYTICAL TECHNIQUES: IR, NMR, MASS SPECT
Page 37
CONCEPT: 13C NMR – GENERAL FEATURES
13C NMR is a more limited type of nuclear magnetic resonance that identifies 13C instead of 1H.
● Due to low natural incidence of the 13C isotope, ______________ is NOT observed. ( ---------) (---------) =
● All of the other principles from 1H NMR apply, except that we must learn new shift values:
C – H 5 - 45 C = C 100 - 140
C ≡ C 65 - 100 Benzene 120 - 150
Z – C – H 30 - 80 Carbonyl 160 - 210
EXAMPLE: How many 13C signals would ethylbenzene give?
EXAMPLE: Which compound(s) will give only one peak in both its 1H and 13C spectra?
ORGANIC - CLUTCH
CH. 15 - ANALYTICAL TECHNIQUES: IR, NMR, MASS SPECT
Page 38
CONCEPT: STRUCTURE DETERMINATION – MOLECULAR SENTENCES
The holy grail of this section is structure determination.
● You may be asked to produce a structure from scratch given only a MF, NMR Spectrum and IR Spectrum.
● Our goal is to build a strong “molecular sentence” by gathering clues, then propose drawings.
How to build a molecular sentence:
1. Determine IHD.
2. Analyze NMR, IR and splitting patterns, integrations for major clues (i.e.).
● NMR = 9.1 ppm __________________
● IR = 1710 cm-1 __________________
● Triplet/Quartet __________________
● 9.1 ppm (2H) __________________
3. Calculate 1H NMR Signal : Carbon Ratio.
● Ratio < ½ suggests symmetrical, whereas ratio > ½ suggests asymmetrical
□ Never rule out a structure based on symmetry (you may not be able to visualize it)
4. State the number of 1H NMR signals needed.
--- DRAW POSSIBLE STRUCTURES ---
5. Use a combination of Shifts, Integrations, and Splitting to confirm which structure is correct.
EXAMPLE: Build a strong molecular sentence using the following data.
MF: C4H6O2 IR: peak at 2950 cm-1 1H NMR
peak at 2700 cm-1 - 2.2 (doublet, 4H)
peak at 1720 cm-1 - 9.4 (triplet, 2H)
ORGANIC - CLUTCH
CH. 15 - ANALYTICAL TECHNIQUES: IR, NMR, MASS SPECT
Page 39
PRACTICE: Propose a structure for the following compound that fits the following 1H NMR data:
Formula: C3H8O2 1H NMR: 3.36 δ (6H, singlet)
4.57 δ (2H, singlet)
ORGANIC - CLUTCH
CH. 15 - ANALYTICAL TECHNIQUES: IR, NMR, MASS SPECT
Page 40
PRACTICE: Propose a structure for the following compound that fits the following 1H NMR data:
Formula: C2H4O2 1H NMR: 2.1 δ (singlet, 1.2 cm)
11.5 δ (0.5 cm, D2O exchange)
ORGANIC - CLUTCH
CH. 15 - ANALYTICAL TECHNIQUES: IR, NMR, MASS SPECT
Page 41
PRACTICE: Propose a structure for the following compound that fits the following 1H NMR data:
Formula: C10H14 1H NMR: 1.2 ppm (6H, doublet)
2.3 ppm (3H, singlet) 2.9 ppm (1H, septet) 7.0 ppm (4H, doublet)
ORGANIC - CLUTCH
CH. 15 - ANALYTICAL TECHNIQUES: IR, NMR, MASS SPECT
Page 42
PRACTICE: Propose a structure for the following compound, C7H12O2 with the given 13C NMR spectral data:
Broadband decoupled 13C NMR: 19.1, 28.0, 70.5, 129.0, 129.8, 165.78 δ DEPT-90: 28.0, 129.8 δ DEPT-135: 19.1 δ (↑ ), 28.0 (↑ ) , 129.8 δ (↑ ) , 70.5 δ (↓) & 129.0 δ (↓)
ORGANIC - CLUTCH
CH. 15 - ANALYTICAL TECHNIQUES: IR, NMR, MASS SPECT
Page 43
PRACTICE: Propose a structure for the following compound, C5H10O with the given 13C NMR spectral data:
Fully Broadband decoupled 13C NMR and DEPT: 206.0 δ (↑ ); 55.0 δ (↑ ); 21.0 δ (↓) & 11.0 δ (↑ ).
ORGANIC - CLUTCH
CH. 15 - ANALYTICAL TECHNIQUES: IR, NMR, MASS SPECT
Page 44
PRACTICE: Provide the structure of the unknown compound from the given information.
Formula: C4H10O IR: 3200-3600 cm-1 1H NMR: 0.9 ppm (6H, doublet)
1.8 ppm (1H, nonatet) 2.4 ppm (1H, singlet) 3.3 ppm (2H, doublet)
ORGANIC - CLUTCH
CH. 15 - ANALYTICAL TECHNIQUES: IR, NMR, MASS SPECT
Page 45
PRACTICE: Provide the structure of the unknown compound from the given information.
Formula: C4H9N IR: 2950 cm-1, 3400 cm-1 1H NMR: 1.0 ppm (4H, triplet)
2.1 ppm (4H, triplet)
3.2 ppm (1H, singlet)
ORGANIC - CLUTCH
CH. 15 - ANALYTICAL TECHNIQUES: IR, NMR, MASS SPECT
Page 46
CONCEPT: MASS SPECT- INTRODUCTION
Mass Spectrometry is usually accomplished through a technique called electron impact ionization (EI)
Electrons are beamed at molecules, generating high energy intermediates called radical cations
● This is known as the molecular ion _______ or as the parent ion.
● Only fragment cations are deflected by the magnetic field, the smaller ones more than the bigger ones.
□ Detects the mass-to-charge ratio ______, which means that it detects the MW of cationic fragments
ORGANIC - CLUTCH
CH. 15 - ANALYTICAL TECHNIQUES: IR, NMR, MASS SPECT
Page 47
CONCEPT: MASS SPECT- FRAGMENTATION
Ionization Potentials:
Some electrons require less energy to ionize than others.
Simple Fragmentation Mechanisms:
The molecular ion will often fragment into smaller, sometimes more stable ion fragments.
● The stability of the cation fragment usually determines the relative amounts of fragments observed
● Radicals tend to form on the less stable side of the fragment
Common Splitting Fragments:
EXAMPLE: Fragmentation of Butane
ORGANIC - CLUTCH
CH. 15 - ANALYTICAL TECHNIQUES: IR, NMR, MASS SPECT
Page 48
PRACTICE: Draw the most likely ion fragment for the following molecules
a.
b.
PRACTICE: Propose the molecular ion and likely fragmentation mechanism for the following molecule. What would be the
value of the base peak?
ORGANIC - CLUTCH
CH. 15 - ANALYTICAL TECHNIQUES: IR, NMR, MASS SPECT
Page 49
CONCEPT: MASS SPECT- COMMON ISOTOPES
Isotopes are often visible on a mass spectrum, due to their differing weights. They can be used for structure determination.
Understanding the (M + 1) Peak
1.1% of all carbon is found as 13C, adding a small but distinctive (M + 1) peak proportional in size to the number of carbons.
● This proportion is fairly consistent, so it gives rise to two helpful equations
Understanding the (M + 2) Peak
The halogens –Cl and –Br give distinctive (M + 2) peaks due to their unusual patterns of isotopic abundance
● 35Cl = 75.8% and 37Cl = 24.2%, yielding an approximate 3:1 ratio at (M + 2)
● 79Br = 50.7% and 81Br = 49.3%, yielding an approximate 1:1 ratio at (M + 2)
The Nitrogen Rule
Unlike carbon, nitrogen forms 3 bonds. We can use this information to determine the number of nitrogens in a molecule.
● Even or odd molecular weight of parent ions usually indicates and even or odd number of nitrogens present
ORGANIC - CLUTCH
CH. 15 - ANALYTICAL TECHNIQUES: IR, NMR, MASS SPECT
Page 50
PRACTICE: Propose the number of carbons for a compound that exhibits the following peak in its mass spectrum:
a. (M)+• at m/z = 72, relative height = 38.3% of base peak
(M+1)+• at m/z = 73, relative height = 1.7% of base peak
b. Predict the approximate height of the (M + 1) peak for the molecule icosane, molecular formula C20H42.
c. Draw the expected isotope pattern that would be observed in the mass spectrum of CH2Br2. In other words, predict
the relative heights of the peaks at M, (M + 2), and (M + 4) peaks.
ORGANIC - CLUTCH
CH. 15 - ANALYTICAL TECHNIQUES: IR, NMR, MASS SPECT
Page 51