ochem lab quiz 2

What type of spectroscopy is this: measures the bond vibration frequencies in a molecule and is used to determine the functional group

infrared (IR)

What type of spectroscopy is this: fragments the molecule with ionization and measures the masses (molecular weight)

mass spectrometry (MS)

What type of spectroscopy is this: detects signals from hydrogen atoms and can be used to distinguish isomers

nuclear magnetic resonance (NMR)

used to show correlations seen between hydrogen atoms in a molecule

1H NMR

gain structural information from carbon atoms

13C NMR

What type of spectroscopy is this: uses electron transitions to determine bonding patterns

ultraviolet

What is the benzene range in 13C NMR

about 95-175

what is the equation for EU and what does it mean

EU = 1/2(2(C) + N + 2 - H - X) number of pi bonds or rings

at what cm^-1 peak in IR does the NH bunny ears/cow udders appear

3200-3500

what are the two different (IR) molecular vibrations 

stretching (valence bond vibrations 4000-1500 cm-1) and bending (deformation vibrations below 1500)

what type of bonds have the highest frequency/wave number of absorption (cm-1)

atoms single bonded to ONLY one hydrogen (2500-3600, ex. OH, NH, CH)

what is the order of bonds from highest to lowest frequency/wave number of absorption (cm-1)

bonds to H, triple bonds, double bonds, single (carbon) bonds

what does a strong IR peak transmittance at around 2900 mean

C-H bond

How do sp2 and sp3 CH bonds differ in appearance on IR spectra

slightly above 3000 is sp2 or sp, below is sp3 (sp2 is shifted left)

what does this pattern between 2800 and 3000 cm-1 (IR) mean

alkanes

What do the cow udders/bunny ears (two peaks) in IR between 3200-3500 cm-1 indicate

NH bond

What does a strong peak in IR around 1700ish usually indicate

C=O (double bond)

What does a strong peak in IR around 1100ish usually indicate

C-O (single bond)

What does a doublet of doublets between 7 and 8 ppm indicate on H NMR

aromatic ring (with 2 different groups 1,4 to each other)

what causes a downfield (higher number) shift in NMRs

higher electronegativity (or proximity to EN/EWG) and internalization

What carbon has a singlet at 2.1ppm

the alpha carbon (next to C=O)

Which type of NMR is 0-12 ppm

1H NMR

Which type of NMR is 0-220 ppm

13C NMR

How does proximity to oxygen or other EWG (ex. Nitrogen) impact NMR ppm

more deshielded = shift downfield (higher numbers)

What does a sharp peak around 3300 cm-1 indicate

alkyne