Question

NAME SECTION DATE TECH 711/Using Nuclear Magnetic Resonance Spectroscopy. to Identify an unknown Compound Pre-Laboratory Assignment 1. Briefly define the following terms: (a) chemical shift (b) spin-spin coupling (c) coupling constant 2. Using an appropriate reference, draw the structure of 4-propoxybenzaldehyde. 3. Predict the splitting pattern for each kind of proton in the 'H NMR spectra of the following molecules: CH3CH2CH2Br (CH3)2CH-O -OCCH3 COCH GHz CH3 TCCH HỌC-C-o-CH, CH3 (d)

Answer 1

Answen 2 (a) Chemical shift The frequency of the resonance, expressed with reference to a standard compound which is defined to be at Oppm. (6) Spin-spin coupling - The interaction between the spin magnetic moments of different electorns and for nudei give rise to spin - spin coupling. In NMR spectroscopy it gives rise to multiplet patterns.' (c) Coupling constant :- Is the distance between the peaks in a given multiplet is a measure of the magnitude of splitting effect, it is referred to as Coupling constant and is denoted by the symbal I. Answer 2: 4-propoxybenzaldehyde i Benzaldehyde means van of Ede Zenzene ring containing aldehyde 4- propoxy means - 0-CH ₂ -CH₂-CH3 at 4th position So structure is rapoxy means H O-CH2 - CH₂ - CH₂ - CH₂