General Information Flashcards
what is the formula for degrees of unsaturation?
(2C + 2 + N - X - H)/2
in the degrees of unsaturation formula, what does each variable represent?
C = carbon, N = nitrogen, X = halogens, H = hydrogens
if the DOU is one, what does that indicate?
there is only 1 carbon ring or a pi bond
if the DOU is 2, what does that indicate?
there are 2 carbon rings or 1 carbon ring plus a pi bond
if the DOU is 4, what does that indicate?
there is a high likelihood of an aromatic ring
what types of vibrational modes are IR active?
asymmetric stretching and bending
what is the unit for IR vibrating frequency?
wavenumbers
is the wavenumber increases, what happens to wavelength and energy?
wavelength decreases and energy increases
compared to IR bending, does stretching require more or less energy, and does this lead to an increased or decreased wavenumber?
it requires more energy, resulting in a higher wavenumber
do stronger bonds have a higher or lower wavenumber?
they have a higher wavenumber
what does proton NMR reveal?
the relative numbers of hydrogens in different chemical environments within a molecule
what type of information is provided by NMR?
the number of signals, integration, chemical shift, and multiplicity
what does each NMR signal represent?
a group of chemically equivalent protons
when are two hydrogens chemically equivalent?
if they can be interchanged by a plane of symmetry or by bond rotation
in NMR, what is integration?
it is the area under the signal and is proportional to the number of hydrogens
what information does the chemical shift give us?
it provides us with information about how rich or poor a hydrogens chemical environment is
what is the inductive effect on ppm?
more electronegative atoms nearby results in a higher ppm
what is multiplicity and what does it reveal?
the splitting of a signal into multiple different lines and reveals connectivity
how does vicinal coupling (3-bond coupling) affect multiplicity?
it often leads to splitting because the hydrogens tend to be chemically different
what is the N + 1 rule?
the number of lines in a signal is n +1, with n being the number of chemically non-equivalent neighbors
