Propose a synthesis for 3,5-dichloro-2-methoxybenzoic acid starting from phenol.
Mass Spectrometry Mass Spectrometry is basically an experimental technique where a molecule is bombarded with high energy electrons, breaking the molecule up into various fragments. The abundance of all of the fragments are then recorded in a graph, represented by a mass spectrum. An example of a Mass spectrum is shown below The molecular weight of the molecule is represented by the symbol M . All of the different bars shown in the spectrum represent all of the different fragments that are created after fragmenting the molecule. The higher the bar, the more abundant the fragment will be. The M/Z ratio represents the mass to charge ratio of the ion. Most, if not all, of the fragments shown in the spectrum have a charge of +1 since they are carbocations. Therefore, for our purposes, the m/z ratio simply represents the mass of the fragment. So what do you have to be able to do with a mass spectrum You have to be able to… Determine the molecular weight of the original molecule. (This is usually given, but when it is not, you have to be able to find the molecular weight directly from the mass spectrum) Draw and predict the structures of the most abundant fragments with the corresponding molecular weight shown by the mass spectrum. This is the most common type of question they will ask you regarding MS Be able to predict the presence of certain elements (particularly the presence of Br, Cl, I, N or S) Some VERY important facts to keep in mind: Whenever a molecule is fragmented by an electro