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Today: Brief Review of Mass Spectroscopy Discussion/Review of H-NMR, CMR PowerPoint PPT Presentation


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Today: Brief Review of Mass Spectroscopy Discussion/Review of H-NMR, CMR Next time (our last lab lecture): Your questions Final Exam at 2:10 pm in your Lab! Exam covers the material of the second half of the semester(only): “Unknowns”.

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Today: Brief Review of Mass Spectroscopy Discussion/Review of H-NMR, CMR

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Today brief review of mass spectroscopy discussion review of h nmr cmr

  • Today:

  • Brief Review of Mass Spectroscopy

  • Discussion/Review of H-NMR, CMR

  • Next time (our last lab lecture):

  • Your questions

  • Final Exam at 2:10 pm in your Lab!

  • Exam covers the material of the second half of the semester(only): “Unknowns”.

  • Study/ review lab lectures, your labs, practice questions, sample final (in eres file).

  • Same rules as for Midterm. No calculator needed.

  • Spectral correlation charts will be provided.


Mass spectrometry summary examine your unknown 3 mass spectrum

Mass SpectrometrySummary(Examine your Unknown #3 Mass spectrum!)

  • Molecular weight:

  • Molecular ion peak M+ ?

  • odd-numbered (N ...) ?

  • isotope peaks (Cl, Br)?

  • Alcohols …

  • Recognize typical fragments:

  • H2O, alkyl, acyl, tropylium ion …


Today brief review of mass spectroscopy discussion review of h nmr cmr

Weights of common fragments or neutral losses


Today brief review of mass spectroscopy discussion review of h nmr cmr

phenetole

Benzoic acid

3-methoxytoluene

Salicylaldehyde

M+ = 122

This is the mass spectrum for which compound?

91

77

107


Basic information from proton nmr examine your unknown 3 h nmr spectrum

NMR

Basic Information from Proton NMR(Examine your Unknown #3 H-NMR spectrum!)

Number of signals

Number of different types of protons

Chemical shifts

Type of environment for protons

Integration

Ratios of numbers of protons

Splitting of Signals

Information about neighboring protons

Solvent peaks …..


Proton nmr chemical shifts for 1 h nmr the scale generally extends from 0 12 ppm tms standard

Proton NMR Chemical Shifts ()For 1H NMR, the scale generally extends from 0-12 ppm(TMS standard)

  • Simple hydrocarbon protons absorb in the region 0.5-1.5

  • Protons on a carbon adjacent to a carbonyl are shifted to 2 ppm (acetone!)

  • Electronegative atoms (O, halogens) move protons to 3-4

  • Alkene protons are shifted to 5-6

  • Aromatic protons to 7-8 (Amide CONH is also found here)

  • Aldehydic protons to 10

  • Most highly shifted protons are generally those of carboxylic acids, with values of 12

  • Can also be far downfield: phenol OH, enol


Today brief review of mass spectroscopy discussion review of h nmr cmr

Proton NMR Chemical Shifts for Common Functional GroupsFor 1H NMR, the scale generally extends from 0-12 ppm


Proton nmr common splitting patterns

Proton NMR Common Splitting Patterns

A

B

J’s (Hz)!


Practice proton nmr

Practice Proton NMR


Practice proton nmr1

Practice Proton NMR


Http www aist go jp riodb sdbs cgi bin cre index cgi

http://www.aist.go.jp/RIODB/SDBS/cgi-bin/cre_index.cgi


Today brief review of mass spectroscopy discussion review of h nmr cmr

13C NMR Chemical Shifts for Common Functional GroupsRange 0-220 ppm (TMS standard)Proton noise-decoupledIntegration not useful

  • (Examine your Unknown #3 CMR spectrum!)

  • Simple methyl carbons tend to absorb in the region 15-30, simple methylene carbons are shifted to 20-65

  • Electronegative atoms (O, halogens) move attached carbons to 40-80

  • Alkyne carbons are shifted to 70-90,

  • alkene carbons to 100-150,

  • aromatic carbons to 120-170

  • Most highly shifted carbons are generally those of carbonyls, with values of 180-220.


13 c nmr chemical shifts for common functional groups

13C NMR Chemical Shifts for Common Functional Groups


13 c nmr practice

How many types of C ?Indicated by how many signals there are in the spectra (solvent peaks ….)

What types of C ?Indicated by the chemical shift of each signal

13C NMR Practice


13 c nmr practice1

13C NMR Practice

Symmetry!


13 c nmr practice2

13C NMR Practice

  • How many signals would you expect in the 13C spectrum of

  • o-xylene

  • m-xylene

  • p-xylene?


Today brief review of mass spectroscopy discussion review of h nmr cmr

  • Next time (our last class):

  • Your questions

  • Final Exam at 2:10 pm in your Lab (Begin studying early!)

  • Exam covers the material of the second half of the semester: “Unknowns”.

  • Study/ review lab lectures, your labs, practice questions, sample final.

  • Same rules as for Midterm. No calculator needed.

  • Spectral correlation charts will be provided.

  • How your C336 class grade is calculated ….


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