ABSTRACT
Other notations have been proposed [51] but the only one to be used extensively has been that proposed by Wiswesser [5,52]. However, one unusual notation is worthy of mention because it is a type of linear chemical formula. Read and Milner [31,32] have developed a method for generating unique line formulas for acydic structures that is suitable for both manual and machine encoding and decoding. Their coding algorithm is automatic and does not require chemical intuition. The unique notations generated by thdr algorithm, such as the first shown in Figure 5, are readily recognizable by chemists. Read has extended the concept to ring systems with substituents [53]. For example, the second notation shown in Figure 5 describes a structure that can be constructed by drawing a string of eight carbon atoms, numbering them 1 through 8, completing a ring by connecting the last atom to atom 3 (C8*3), backtracking to atom 1 and drawing a string of five carbon atoms attached to it, dosing a second ring by connecting the last atom to atom 1 (1C5-1), numbering the added atoms 9 through 13, and adding the substituents. The substituent data (indnding hydrogen) precede the ring data and in each case the substituent data indude the ring atom. Thus, a hydrogen atom is attached to each of carbons 4,5, and 8; a chlorine atom is attached to carbon 11, and so on.
