Spectroscopy Exam 336

OCHEM 336 spectroscopy exam (Peak is one like spike in a signal, signal is a cluster (i.e doublet, singlet), full signal is like all of the signals for one H)

Degrees of Unsaturation Equation

DU = nc - (nH+X/2) + (nN/2) + 1

OR DU = 1/2(2C + 2 + N - H - X)

What does proximity to an electronegative atom or a pi bond do to a full signal?

It causes it to be shifted downfield

Integration numbers are _____?

relative

n + 1 rule (H NMR)

Peaks in a signal = individual (not type of) neighbors + 1

n + 1 rule (C NMR)

N = number of H on the carbon + 1

Coupling constants (J values) measure

the distance between peaks in Hz

Jab of trans H alkene H

15 Hz

Jab of cis H alkene H

10 Hz

Jab of Geminal H on alkene

2 Hz

Jab of alkyl H on alkane HC-CH

7 Hz

J ortho of ortho H

6.5 - 8.5 Hz

J meta of meta H

1 - 3 Hz

J para H

0 - 1 Hz

H NMR Doublet ratio

1:1

H NMR Triplet ratio

1:2:1

H NMR Quartet ratio

1:3:3:1

Quartet (2H) and triplet (3H)

Ethyl Splitting pattern (H NMR)

Tiny Septet (1H) and doublet (6H)

Isopropyl splitting pattern (H NMR)

Tall singlet (9H)

Tert-Butyl Splitting pattern (H NMR)

General splitting rules

Triplet (2H) and Triplet (2H)

-CH2CH2- splitting pattern (H NMR)

Doublet of Doublet and quartet and doublet of a doublet

Vinylic splitting pattern (H NMR)

Doublet (2H) and doublet (2H)

Para splitting pattern (H NMR)

Triplet (1H ~7.25) and doublet (1H ~7) and singlet (1H ~6.9) and doublet (1H ~6.8)

Meta splitting pattern (H NMR)

Doublet (1H ~8.1) and triplet (1H ~7.6) and doublet (1H ~7.1) and triplet (1H ~7)

Ortho splitting pattern (H NMR)

Doublet (1H ~8.1) and doublet of a doublet (1H ~7.13) and doublet (1H ~7.06)

3 other substituents on benzene (H NMR)

If integrating: Carbon NMR Peak height equals what

roughly the number of carbons

IR

Shows functional groups

NMR

Shows molecular formula and arrangement of carbons and hydrogens

Mass spec

Shows molecular formula

IR Primary amine

Double fangs

IR Secondary amine

One fang one broken

M+ (Mass spec)

Molecular weight of compound

Broad signal in IR

H bonding present (concentrated solution)

Narrow signal in IR

Less H bonding present (dilute solution)

Hairy beard in IR + spike at 1700

Carboxylic

Mass spec, # of carbons equation

((M+1)/M)100 = X, X/1.1 = Number of carbons

Nitrogen present in mass spec

If the entire molecular weight is odd, it is possible you have an odd number of Nitrogens, and if the entire molecular weight is even it is possible you have an even number of nitrogens

Cl and Br in mass spec

(M + 2) peak

Cl ratio in mass spec

100:30

Br ratio in mass spec

100:100

MW of Carbon

12

MW of Oxygen

16

MW of Hydrogen

1

MW of Nitrogen

14

MW of Br

79

MW of Cl

35

Base peak is (Mass spec)

100 (the tallest peak) then everything else is relative to that (abundance)

Stability of a fragment (mass spec) is directly related to

The most stable is tertiary carbocation/radical to least stable is CH3+ carbocation/radical

(H NMR) The location of the full signals tell you ____

The types of protons

Downfield

Deshielded (Left)

Upfield

Shielded (Right)

The number of peaks in a signal

Number of neighboring protons (even symmetrical) + 1

Area under the full Signal

Tells you the ratio of the types of protons

Area under the full signal is also called

integration

Deshielding -- Shielding effects of different halogens (NMR)

F Cl Br I CH4

Deshielding -- Shielding effects of amount of Cl (NMR)

CCl4 CHCl3 CH2Cl2 CH3Cl CH4

Proximity to halogen (NMR) Deshielding -- Shielding

Alpha Beta(1/5) Gamma

Chemical shift of O in ester (not carbonyl) (NMR)

+ 3.0 ppm

Chemical shift of OH or OR (NMR)

+ 2.5 ppm

Chemical shift of carbonyl O in ketone, aldehyde, ester, or carboxylic acid (NMR)

+ 1 ppm

Chemical shift of aryl H (NMR)

+ ~6-8 ppm

Chemical shift of methyl H (NMR)

+ ~0.9

Chemical shift of methylene H (NMR)

+ ~1.2

Chemical shift of methine H (NMR)

+ ~1.7

Chemical shift of aromatic methyl H (NMR)

+ ~2.5

To get the ratio of C or H in NMR

Find the smallest line (not C=O or aromatic) and that is 1C (NOT ONE CARBON BUT RATIO 1)

To get the exact number per full signal from ratio

Add all the ratio numbers, then divide each individual ratio by the total, and then multiply by the number of H from the formula (from mass spec)

Mass spec the biggest number peak is

molecular weight (but but there is also M+2 and M+1 so its not technically the biggest number)

1 neighbor to Hydrogen (H NMR)

1 split = Doublet

2 neighbor to Hydrogen (H NMR)

2 split = Triplet

3 neighbor to Hydrogen (H NMR)

3 split = quartet

Doublet of doublet

Two types of neighbors (1 each) in different chemical settings

Doublet of triplet

Two types of neighbors (1 on higher constant, 2 on lower constant) in different chemical settings

__ of a ___ (NMR)

Higher constant of a lower constant

Chemical shift of aldehyde (H NMR)

+ ~10

(Exchanges) in NMR

H connected to Oxygen or Nitrogen

Mass spec: If there's no Cl and no Br....(with a lot of MW left)

NO2 is your next best bet