4- Methyl-2-pentanone mass spectrum

In the mass spectrum of 4-methyl-2-pentanone a McLafferty rearrangement and two other major fragmentation pathways occur. Propose reasonable structures for these fragment ions and specify the m/z value for each. 

You have two bottles (A and B), but the labels have fallen off and blown away. You know that one is 3-pentanone and the other is methyl butanoate. You take a mass spectrum and an infrared spectrum of each to help determine their identity. Describe how you would distinguish A and B. 

The mass spectra of 3-methyl-2-pentanone and 4-mefhyl-2-pentanone are as follows. Explain which spectrum goes with which compound. What is the structure of the ion responsible for the peak at m/z 43 in each spectrum ... 

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