Year 12s: what will be the first way you research your future options? >>

Mass Spectroscopy question?

I need to deduce facts about this compound by looking at the mass spectrum for this compound, in particular making reference to peaks at 166 + 168. I'm unsure though :frown:

Reply 1

charco

Study Forum Helper

Original post by Funky_Giraffe

I need to deduce facts about this compound by looking at the mass spectrum for this compound, in particular making reference to peaks at 166 + 168. I'm unsure though :frown:

Two peaks with a separation of 2 m/z at m/z=166 & 168 must be due to isotopes as there is no element with a mass of 2

Hence you can expect your molecule to have an element with two common isotopes that differ by 2 mass units, such as bromine or chlorine.

Also, this repeats at 107 and 109 suggesting that the same element is influencing the spectrum here as the ratio of the intensities is the same as the higher double peak.

There is no further double peak lower in m/z suggesting that the element alone has a mass of 107 or 109, which fits silver.

Don't like the large peak at around 88 though ... (maybe due to a double charge ion?)

But nothing else is seen until m/z =59

CH₃COOAg - silver ethanoate

The difference between 168 and 109 is 59 units, and then the (more of less) expected pattern for a carboxylic acid ...