Chapter 29 chrom + spec

• a mobile phase is passed over a stationary phase and each compound has a different affinity for each phase • this allows compounds to move at different rates

• stationary phase of silica gel (SiO2) or alumina (Al2O3) • a sample is added to starting point on the plate, placed in liquid solvent which will get drawn up • the height of the solvent front is marked the solvent front

• a stationary phase of solid silicone polymers or a liquid long chain alkane coated inside capillary tube • a sample is injected and vaporised and pushed through by inert gas e.g He or N2

• chemical shift is relative to TMS • each TMS molecule has 12 equivalent protons which give it a distinct NMR signal which is given the value delta = 0 ppm • TMS is very unreactive so can be removed from the sample at the end • Chemical formula: Si(CH₃)₄

• depending on the environment - NMR requires a different a different energy and frequency • this producers different absorption peaks at chemical shift

• NMR is usually carried out in solution and to avoid unwanted signals • a common hydrogen is CHCl3 (where the hydrogen is deuterium) this peak is removed from the spectrum

• if 2 or more protons are equivilant (same proton environment) they will absorb at the same chemical shift increasing the size of the peak

• tells how many protons in that environment