CHEM 2211 1st Edition Lecture 18Outline of Last Lecture I. Clicker questionsII. Chapter 6 alkenes Outline of Current Lecture I. Chapter 15 CNMR Current LectureC NMR tells how many different types of carbons there are in compound. C NMR works much like H NMR in the way it produces signals and how many signals are produced. The number of signals produced in a CNMR are determined by the environment of each Carbonin the compound just like in HNMR. If they have equivalent environments they will have one signal together. Each chemically equivalent environment will produce a signal. Let’s look at some example compounds and their number of signals: CH3CHCH2CH3 OHHow many different signals are produced in from this compound? Label them. A B C D CH3 CH CH2 CH3 OHThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.There are 4 different signals because none of the carbons share the same environment. OH does not produce a signal at all because we are now looking at C NMR not H NMR so only carbons are included here. The two CH3 atoms have different environments so they have 2 different signals. Splitting does occur in CNMR spectra but normally each signal is a singlet due to the way in which the results are recorded, but if the spectrometer is run in a proton coupled mode splittingdoes occur. Splitting of C signals follows the N+1 rule but instead of being split by adjacent hydrogens the C signal is split by the number of hydrogen directly bonded to it. Example: - A methyl carbon CH3 o Signal would be a quartet o Bonded to 3 hydrogens plus 1 - A methylene carbon CH2o Signal would be a triplet o Bonded to 2 hydrogens plus 1- A CH o Signal would be a doublet o Bonded to 1 hydrogen plus 1 Here’s a chart for easy chemical shift
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