Crystallization techniques 2,8 diol

Some commonly used resolving agents are summarized in Table 1 [15-48]. The formation of non-covalent diastereomeric salts is driven by ionic interactions. Therefore, suitable functional groups (acidic or basic) are required to be present in both counterparts. This makes impossible a direct application of the diastereomeric crystallization technique to several classes of chiral compounds such as alcohols, aldehydes, ketones, diols, thiols, dithiols, and phenols. This is a critical disadvantage of this technique. The compounds of the above-mentioned groups may be transformed to their more polar derivatives and resolved as such. However, this requires an additional reaction step, and reagents, and the recovery of the starting material after the resolution may not always be easy. 

Our understanding of the importance of steric factors was initiated by structure determinations by X-ray diffraction techniques of two trans-diols of benz[a]anthracene (89), XVI and XVII, shown in Figure 12. The crystal structures showed diequatorial... 

As mentioned before, a Pseudomonas incognita was isolated by enrichment technique on the monoterpene alcohol linalool that was also able to grow on geraniol, nerol and limonene [36]. The metabolism of limonene by this bacterium was also investigated [37]. After fermentation the medium yielded as main product a crystallic acid, perillic acid, together with unmetabolised limonene, and some oxygenated compounds dihydrocarvone, carvone, carveol, p-menth-8-en-1 -ol-2-one, p-menth-8-ene-1,2-diol or p-menth-1 -ene-6,9-diol (structure not fully elucidated) and finally / -isopropenyl pimelic acid. 

We have attempted crystal growth of assorted diacetylenes by both liquid and vapor phase techniques. Urethane substituted diacetylenes are of particular interest because they are melt-stable and radiation polymerizable. Moreover, the polymer of the bis-ethylurethane of 5,7- dodecadiyn -1,12- diol (ETCD) exhibits the low energy ("excitonic") absorption peak found in the L-B PDA acid multilayer above and in poly-PTS, but is found in poly-TCDU at higher energy (32). Hence, we hoped to assess the role of this low energy absorption in nonlinear optical phenomena. 

---