Primary Data Processing: Preparation, Input and Checking

Abstract

This chapter will focus on the processing and preparation of the raw spectral data prior to utilizing computer-assisted structure elucidation approaches. Almost any error made during the data preparation procedure can lead to erroneous structures being derived as a result of the elucidation process. The preparation of the input data is therefore a critical part of the process. CASE systems utilize 1D and 2D NMR spectra but also other forms of spectral data including mass and infrared spectra and all forms of data need to be entered into the system in a manner by which the algorithms can consume the data to elucidate a structure. Most procedures described in this chapter are implemented into the Structure Elucidator system. They will be illustrated using the example of strychnine. The chapter will use the step-by-step construction of the Molecular Connectivity Diagram (MCD) of strychnine to demonstrate how various forms of data influence the elucidation process. During the process we will examine the influence of an accurate molecular formula as a boundary condition, the challenges of accurate peak-picking in 2DNMR and some of the complex problems that can be faced in real life situations. The main idea of a method developed for the logical analysis of a molecular connectivity diagram to check a set of 2D NMR data for the presence of contradictions is described. The method is implemented into the expert system Structure Elucidator.