Objectives Chapters 12-1`4 Brown Foote & Iverson 4^th ed. Spectroscopy for Organic Chemistry.

You should review information about IR and H NMR spectroscopy found in Chapters 12 and 13.

1. Infrared spectroscopy: You should be able to look at an Ir spectrum without the use of a spectral chart and determine if the spectrum shows an OH absorption (3300-3100 cm^-1 broad and intense) a carbonyl (1730-1685 cm^-1 very intense and n narrow), CN 2200-2250 (medium intense and very narrow) And at the 3000 cm^-1 absorbance To check if the compound is all saturated

C-H (below 3000cm^-1) or above 3000cm^-1 =C-H absorbance.

2. You should be able to look at an H nmr spectrum and tell how many protons you are looking at (the total area under each peak tells you how many of each kind of protons you have. You should be familiar with the chemical shifts of protons. carboxylic acid H 12 ppm. aldehyde 10 ppm. aromatic 7-8 ppm, vinylic 4.6-5.7 ppm, OH variable .5-6 ppm, CH₃ 0.8-2.3 TMS 0.0 ppm (See the appendix A-4)

3. By looking at the splitting of H nmr peaks you should be able to tell how many protons are on the adjacent carbon atom.

Singlet indicates no Hs on adjacent C, a doublet indicates one proton on the ad ascent carbon, triplet indicates a CH₂ group next door, a quartet indicates that there the adjacent carbon is a group. A two-proton doublet down field from a three-proton triple indicates an ethyl group. A six-proton doublet up field from a complex 1 proton septuplet indicates an isopropyl group

4. By counting the area under the peak of an aromatic you should be able to tell if you have a mono substituted benzene, (five proton signal), disubstituted benzene (four proton signal). If you have a disubstituted aromatic, there are ways to tell if it is o m or p. Ir spectrum 800-600 cm^-1, and splitting pattern of the NMR aromatic protons.

5. C13 NMR. Because the protons have been double irradiated the C-13 signals are usually singlets and the chemical shift tells you what kind of carbons you have. See the appendix pg. A-5.

TMS 0.0 aliphatic C-H 10-80 ppm, C-OH 40-80 ppm, C=C 100-150 ppm, aromatic C110-160 ppm, ^carboxylic acid, ester and amide carbonyl C = 165-180 ppm, aldehyde or ketone carbonyl C = 180-215 ppm

6. Mass spectroscopy.

With mass spectroscopy you are looking at the positively charge fragments of a shattered compound. The compound was vaporized and then shattered with 70 eV electrons, or in some cases fast moving ions (chemical ionization). The fragment represents the most stable cations produced from the fragmentation process. The molecular ion is the peak with the highest mass (but not very intense). It represents the molecular weight of the compound. Some times you will see a M+1 or a M +2 peak of lower intensity due to isotopes. The most intense peak is called the base peak and itsd intensity is set at 100. All other peaks have intensities less thatn 100. The base peak represents the most stable cation fragment.

By looking at a mass spectrum you want to focus on the parent ion.

7. Be able to work the following problems at the end of chapter 12. 5, 6, 7, 11 At the end of chapter 13 work problems 13, 14, 16, 17. At the end of Chapter 14 try problems 16, 24, 31, & 32