1. The problem statement, all variables and given/known data I've been given the IR spectrum, 1H NMR, and Mass Spec data for an unknown and must identify it correctly and assign all significant spectroscopy/spectrometry signals to the molecule accordingly. I am probably 95% sure that my compound is ethyl phenylacetate, and I've assigned all peaks in the IR and 1H NMR, but I'm having some trouble with a couple signals in the mass spec print out. Here is a link to a pdf of all the data printouts, but the most relevant is the mass spec data (unless someone figures out that I'm actually wrong in identifying the compound as ethyl phenylacetate): http://dl.dropbox.com/u/1406355/all%20data.pdf [Broken] 2. Relevant equations (I don't think anything goes in this section for this type of problem.) 3. The attempt at a solution Namely, I cannot figure out the m/z ratios: 39, 51, 65, and 105. I've assigned the rest of the m/z ratios: 15=methyl cation, 29=ethyl cation, 91=benzyl cation, 119=benzyl acylium cation, and 164=molecular ion. Any chance someone might know where to help me start with the rest? I thought maybe it was some sort of McLafferty rearrangement but I don't think so because the m/z wouldn't match up to any of the above. Thanks very much for your help!