HNMR
What is the significance of the number of signals?
What is to the number of unique hydrogen atom types in the molecule
Correlation Spectroscopy (COSY) allows for the correlation of:
What is protons with protons on neighboring carbon atoms?
What does the number of peaks on a GC graph show?
What is the number of compounds present in the sample?
. What types of energy transitions correspond with IR spectroscopy?
a. Electronic
b. Nuclear spin
c. Vibrational
d. Rotational
What is vibrational?
What is the information obtained from carbon nmr?
What is the number of signals?Nonequivalent Carbons, Chemical shifts (δ) away from 0 (TMS)
What is revealed by integration of the signals in a ¹H-NMR spectrum?
What is the relative energy absorbed or released at each chemical shift. It reveals ratios of equivalent protons
What information is given by the off-diagonal peaks in a COSY spectrum?
What is off-diagnal peaks indicate that the signals on the vertical and horizontal lines from the peak come from coupled protons
What does the position of each peak on a GC graph show?
What is the retention time for each compound?
What is a wavenumber directly proportional to?
a. Frequency
b. Energy
c. Heat
d. Speed of light
What is energy?
What is the order for carbons that are more substituted vs less substituted if all things are equal?
What is more substituted = further downfield? (less electron density and >ppm)
OH groups are displayed as a...
What is a singlet?
What are represented on the x and y-axes of the COSY spectrum?
What is 1H NMR on the x-axis, and 1H NMR on the y-axis?
What mobile phase is most often used with GC/MS?
What is Helium?
What is an overtone, in terms of wavenumber?
a. Integral multiples of the fundamental frequency (2v, 3v, 4v)
b. Weak peaks around 2000-1800 cm-1 indicating a possible aromatic ring
c. A peak that may be seen around 3400 cm-1 caused by a C=O bond
d. A peak that may be seen around 3000 cm-1 for N-H bonds
e. All of the above
What is E? all of the above
What is the range for hydrocarbons?
What is ~20 with quaternary carbons being most downfield and primary carbons being most upfield
The distance between the centers of the peaks of a doublet is called what?
What is the coupling constant?
Coupling is usually seen over what ranges of bonds in a COSY spectrum?
What is 3-4 bonds?
What is an advantage of GC-MS?
What is the molecules in a specific compound will break up or fragment the same way repeatedly and predictably every time
Hooke’s Law can be used to predict wavenumbers of various functional groups. According to this law, what can be said about weaker bonds?
a. Weaker bonds will exhibit a higher K value, and a lower wavenumber
b. Weaker bonds will exhibit a lower K value, and a lower wavenumber
c. Weaker bonds will exhibit a higher K value, and a higher wave number
d. Weaker bonds will exhibit a lower K value, and a higher wavenumber
What is b? weaker bonds will exhibit a lower K value, and a lower wavenumber
What is in the SP3 carbon range?
What is hydrocarbons and Carbons alpha to double bonds?
A proton Hb is coupled to four equivalent protons Ha. The multiplicity of Hb?
What is Quintet?
What is varied between scans in a COSY experiment?
What is the evolution time?
What causes fragmentation?
What is energetically unstable molecular atoms dissociate as they pass through the ionization chamber of a mass spectrometer
Rank the following from highest to lowest vibrational frequency: C-H, C-Cl, C-O, and C-D.
What is C-H>C-D>C-O>C-Cl? (D)
Why do alkynes show smaller chemical shift than alkenes despite being less electron dense?
What is they produce their own magnetic field which shifts them upfield