tailieunhanh - ORGANIC NOMENCLATURE: Principles of Chemistry II

The sample extraction and concentration steps in this method are essentially the same as in Methods 606, 608, 609, and 612. Thus, a single sample may be extracted to measure the parameters included in the scope of each of these methods. When cleanup is required, the concentration levels must be high enough to permit selecting aliquots, as necessary, to apply appropriate cleanup procedures. The analyst is allowed the latitude, under Section 12, to select chromatographic conditions appropriate for the simultaneous measurement of combinations of these parameters | Chemistry 121 Winter 2001 Course Notes Principles of Chemistry II ORGANIC NOMENCLATURE Introduction Confusion can arise in organic chemistry because of the variety of names that have been applied to compounds common names trade names and systematic names are prevalent. For example a compound of formula C YjHjO has variously been known as phenol carbolic acid phenic acid phenyl hydroxide hydroxybenzene phenylic acid and oxobenzene To help eliminate the proliferation of many names for a compound a systematic IUPAC naming system has been derived to uniquely name the several million organic different compounds based on considerations of their structure. This hand-out will address the naming of simple organic compounds and is by no means complete for instance the compound hexahydroazepinium- 1-spiro-1 -imidazolidine-3 -spiro-1 -piperidinium dibromide may be regarded as being too complicated for this course In general compounds are classified and named by consideration of a the number and types of atoms that are present b the bond types in the molecule and c the geometry of the molecule. Formulae Prior to setting out the rules for naming compounds it is pertinent to review some aspects of formulae. The molecular formula of a compound gives no explicit information about the structure of the compound. The formula C2H6O makes no mention as to how the various atoms are arranged indeed two different compounds share this formula but have different structures and vastly different properties. HH 1 1 H 1 H 1 H C C O H 1 1 H C O C H 1 1 1 1 HH H H ethanol dimethyl ether By writing their formulae in a structural form we can differentiate between these two compounds. ethanol CH3 CH2-OH or CH3CH2OH or C2H5OH dimethyl ether CH3 O CH3 or CH3OCH3 In writing these formulae the atoms after a carbon indicate the elements or groups attached to that carbon. It must be remembered that all C atoms in organic compounds must be involved in four bonds. CH3CHClCCl3 CH3CH CH3 CH2CH CH2 H H Cl 1 1 1