CHE 211 Study Guide - Midterm Guide: Methylene Group, Diethyl Ether, Electronegativity

1. For each of the compounds shown below, determine the following: Number of signals in the 13C NMR spectrum, and · o Approximate chemical shift value for each signal Number of signals in the 'H NMR spectrum, and o o o Approximate chemical shift value for each signal Multiplicity (splitting) of each signal Relative integration of each signal (a) Worked example: WC NMR: 2 unique carbons are present so two signals are expected in the spectrum 40-90 ppmm 0-40 ppm H NMR: 2 unique types of hydrogen are present so two signals are expected in the spectrum. Since they are present in different quantities their integrations will differ, as will their splitting due to different number of adjacent protons 3-4 ppm, quartet, 2H 林林 1 ppm, triplet, 3H

Interpreting Your NMR Spectrum 1. Read the chemical shift of each signal directly from the NMR spectrum by looking at the numbers at the top of the peaks. If the signal is not a singlet, then choose the number from a middle peak 2. To find the number of protons represented by each signal, use the integration numbers that appear below the baseline. You must calculate the ratio of these numbers to get the ratio of numbers of hydrogens represented by each signal 3. Fill in the "splitting" column by looking at each signal and deciding if it is a singlet, doublet, triplet, quartet, or multiplet. You can calculate the J value for a coupling constant by subtracting the chemical shift of one peak from the chemical shift of another peak within the same signal and multiplying by 80, since these spectra were taken on a 80 MHz NMR The J value may be helpful in assigning NMR signals to specific protons 4. To fill in the "assignment" column, assign each signal in the NMR to a set of chemically equivalent protons on your labeled structure. The proton(s) you assign should make sense Esterification, IR, and NMR CHEM 344 Modern Organic Chemistry Laboratory for each of the column headings: the chemical shift will be affected by heteroatoms or aromatic rings near the proton; the integration should match the correct number of equivalent protons for the assignment you are making; the splitting pattern may not be clear, but protons on neighboring carbons generally give reliable splitting patterns (protons on oxygen or nitrogen might not split your assigned proton). You may also need to consider whether you have two overlapping signals: if you have identified four different types of hydrogens, but only see three signals, two signals may be overlapping. The integrations should help you determine if that is the case H NMR Analysis Table: draw the structure with labeled protons in the lab report Coupling Constant (J-value) Assignment ChemicalIntegration Splitting Shift (ppm)

What type of proton NMR signal will proton HL(in compound J) give rise to?* What type of proton NMR signal will proton HM(in compound K) give rise to?* What type of proton NMR signal will proton HN(in compound K) give rise to?* Based on the approach/notation presented in lecture what is the appropriate chemical shift increment for group P that must be used in the process for predicting the chemical shift of proton Hg?* Based on the approach/notation presented in lecture what is the appropriate chemical shift increment for group S that must be used in the process for predicting the chemical shift of proton Ha?* A researcher carried out the following reaction. When the reaction was finished and the two products had been separated, the researcher recorded the NMR spectrum of each product. Unfortunately, the researcher neglected to label the spectra and now doesn't know which spectrum goes with which product. Based on the spectra data provided below which one of the following statements is correct? Spectrum 1 is the NMR spectrum of product T and Spectrum 2 is the NMR spectrum of product U Spectrum 1 is the NMR spectrum of product U and Spectrum 2 is the NMR spectrum of product T Spectrum 1 Single at 7.2 ppm (4H) Spectrum 2 Single at 7.2 ppm (1H) Double at 7.5 ppm (2H) Triple at 7.3 ppm (1H) Which spectroscopic technique uses lower energy, infrared spectroscopy or proton NMR Spectroscopy? A signal has been reported to occur 3520 Hz downfield from TMS in an NMR spectrometer operating at 550 MHz What is the chemical shift of this signal? Pease express your answer with one decimal place Do not include units. Do not use scientific notation. Which one of the following statements in correct? Protons HA and Ha are chemically equivalent Protons HA and Ha are not chemically equivalent Which one of the following statements s correct? Protons Hc and Ho are chemically equivalent Protons Hc and Ho are not chemically equivalent How many unique signals win be exhibited in the proton NMR spectrum of compound E?* How many unique signals will be exhibited in the proton NMR spectrum of compound E?* How many unique signals will be exhibited in the proton NMR spectrum of compound F?* Which carbon atom in compound G bears the least shielded proton(s)?*