Carboxylic acids, addition compounds with identification

Identification of naturally occurring organic sulfur compounds (OSC) is possible by co-chromatography (on capillary GC) and comparison of mass spectra (by GC-MS) with synthesized standards. Methods of preparation of various thiophenes (e.g. from suitable thiophene precursors and coupling with either the appropriate carboxylic acid, aldehyde or alkyl halide) will be outlined in addition to some of their spectral properties (NMR, IR,... 

For the extraction of the first set of compounds, i) the polymer is refluxed with acetone and the silver salts precipitated by the addition of aqueous silver nitrate. After drying the residue is examined by infrared spectroscopy to identify alcohols, thioacids, thiols, and alkyl groups attached to tin. For the extraction of the second set of compounds ii) the polymer is refluxed with 10% aqueous sodium hydroxide prior to the identification of alcohols by gas chromatography then the alkyl groups attached to tin and carboxylic acids are identified. 

Within Hymenoptera, pheromones produced by workers in social colonies are the best studied across many genera, principally in ants [6], with those eliciting trail following most extensively studied. The distinct behavior and the relative ease of the bioassay have resulted in chemical identifications in many species [ 113,114]. Those that have been recently identified are listed in Table 5. In addition, several alarm and recruitment signals have recently been identified. Many of the compounds recently identified in ants have previously been reported as trail or alarm pheromones in other ant species. For example, methyl 4-methylpyrrole-2-carboxylate 64, 3-ethyl-2,5-dimethylpyrazine 65, (9Z)-hexadec-9-enal 66,4-methylheptan-3-ol 67, and methyl 6-methylsalicy-late 68 have been identified as trail pheromone components, and heptan-2-one 69,4-methylheptan-3-one 70, formic acid 71, undecane 61,4-methylheptan-3-ol 67, methyl 6-methylsalicylate 68, and citronellal 72 have been identified as alarm pheromone components [6]. The use of the same chemicals across genera, with some used for very different functions, is an interesting phenomenon. 

A differentiation between the two subcla.sses Ai and Ao is seldom necessary since this is accomplished in connection with the final identification of the individual compounds. A triple union will usually add four atoms of bromine, but this is true also of the diolcfincs. When both hydrogens of acetylene arc replaced by so-called negative groups (phenyl, carboxyl, etc.) only two atoms of bromine are added. Ethylene derivatives containing such negative groups add bromine rather slowly. (Example Addition of Bf2 to cinnamic acid.)... 

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