Cast specific compounds

Caste-specific compounds produced by some male carpenter ants (Camponotus spp.) include 2,4-dimethyl-2-hexenoic acid (396). Brand et al. 176) and Kooenski et al. 177) prepared (396) as a mixture of E-and Z-isomers (Schemes 70 and 71), whereas Katzenellenbogen and Utawanit 178) obtained the pure -isomer (396a) by stereoselective dehydration of p-hydroxy ester (402) via a P-alanoxy enolate (Scheme 72). 

The volatile products in the heads of a large number of Nearctic species of Camponotus have been studied more recently by Duffield 506). In general, mandibular gland secretions were restricted to males although some species produce the same compounds in both sexes and castes. When a compound was produced by both sexes and castes it appeared to be a non-specific alarm pheromone, but the role of cast-specific compounds was not demonstrated. The results obtained by Duffield 506) led to the preparation of a taxonomic key to the various species studied which is based primarily on chemical characters. 

Examination of the venom content of the workers of Solenopsis maboya revealed the presence of (5Z,9Z)-3-butyl-5-methylindolizidine (107), (5E,9E)-3-butyl-5-methylindolizidine (108) and frans-2-methyl-6-nonylpiperidine (109), while analysis of the extract of the queens revealed the presence of a single alkaloid, ris-2-heptyl-5-methylpiperidine (110) (Fig. 19) [117]. Such caste-specific alkaloidic contents has been already been found in other Solenopsis ants [ 118,119] and suggest different roles for these compounds in each caste. 

Animal data suggest that renal and liver effects may occur in humans exposed to high doses of hexachloroethane. Kidney and liver effects are not specific to hexachloroethane. Lesions of the kidney (nephropathy, linear mineralization, and hyperplasia) were reported at 10 mg/kg/day or greater in male rats (NTP 1989). Urinalysis also revealed granular and cellular casts in rats exposed to hexachloroethane (47 mg/kg/day or greater) for 13 weeks (NTP 1989). Because other compounds cause similar effects and because some of these effects are unique to male rats, they are not valuable as biomarkers for human hexachloroethane exposure. 

As mentioned above, the binder/filler ratio determines the fluidity and hence the process technology for a given syntactic composition. The solid line in Fig. 1 shows how the apparent density depends on the relative microsphere concentration in syntactic compounds, provided there are no air inclusions. The lower limit of apparent density is at the concentration at which the filler is most densily packed at this point the material has its highest specific strength (strength per unit apparent density). Experience has shown that the closest packing of the spheres within the binder is obtained when the material is mixed and cast or molded under vacuum 8 10). 

Klochkov, S.C., Kozlovskii, V.I and Belyaeva, N.V. (2005). Caste and population specificity of termite cuticule hydrocarbons. Chem. Nat. Compounds, 41, 1-6. 

However, the lack of analytical methods to distinguish clearly diastereoisomers such as 7a and 7b casts some doubt on the above assumptions. Specifically, it cannot be ensured with ultimate certainty that the reactions have really occurred in the desired manner or whether epimerization has taken place to a certain extent. In the case of 7a/Fe+ and 7b/Fe+, for example, the experimental data clearly reveal the occurrence of diastereoselective dehydrogenation, but the intrinsic SE might even be larger if the samples were not the pure diastereoisomers 7a and 7b but only enriched samples. Epimerization at C(3) is in fact facile via keto/enol tautomerism of the carbonyl compound occurring upon work-up. Therefore, the isotopolog 7c was prepared via an independent synthetic route (N2D2 reduction of 2-methyl-but- -2-enoic acid). As the results obtained with... 

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