Alicyclic group

Polyene and polymethine dyes are two structurally related groups of dyes which contain as their essential structural feature one or more methine (-CH=) groups. Polyene dyes contain a series of conjugated double bonds, usually terminating in aliphatic or alicyclic groups. They owe their colour therefore simply to the presence of the conjugated system. In polymethine dyes, electron-donor and electron-acceptor groups terminate either end of the polymethine chain, so that they may be considered as typical donor-acceptor dyes. 

This relationship is useful for understanding the different intercalation binding constants of hydrocarbons with similar ir systems. This is indicated in Figure 4, by a comparison of data for 1,2,3,4-tetrahydro-BA, DMA and anthracene. For 1,2,3,4-tetra-hydro-BA the presence of a nonplanar alicyclic group is expected to sterically inhibit intercalation. The nonplanar methyl groups of DMA play a similar steric role. However for both 1,2,3,4-te-... 

The major metabolic pathway of the 5,5-disubsti-tuted barbiturates is hydroxylation, usually of the larger of the two substituents, e.g. the phenyl group in phenobarbitone, the 1-methylbutyl group in pentobarbitone, and the alicyclic group in cyclobar-bitone. Hydroxylation ofaliphatic groups at the position is usually at the W—1 (penultimate)... 

Partially hindered heterocyclic amines fused with alicyclic groups as in 18 and 19 impart an excellent light stability effect to PO. The elfect is weaker than that of HAS [39], This may be ascribed to the presence of the a-CH bond in 18 and 19. 

Fig. 32. Possible mechanisms for the thermal decomposition of dioxetanes [adapted from Hummelen et al. (H21), with permission). In (a), a concerted bond cleavage leads directly to two carbonyl products, one of which is in the excited state and emits light (M15, M16). The substituents R1-R4 can be simple alkyl or alicyclic groups. In (b), homolytic bond cleavage leads to a biradical that exists as an equilibrium mixture of singlet-state (f ) and triplet-state (t t) forms. As before, chemiluminescence emission probably occurs via the excited singlet-state carbonyl product arising from the homolytic bond cleavage of the intermediate biradical (R5, R6). The substituents R and Ar can include uncharged alkyl, alicyclic, and aromatic groups.

R = alkyl, subst. alkyl, phenylalkyl, or 5- or 6-membered alicyclic group, and R = alkyl, phenylalkyl, alicyclic group, or tetrahydrofuranyl-methyl, or NR R = heterocyclic group, and the total no. of C atoms in RR R >9 and in RR >4... 

Random co- and terpolymers containing acrylate or methacrylate moieties with pendant alicyclic groups... 

It can be concluded that polyalicyclic cardo groups such as admantane and norbor-nane-type groups are thermally more stable than alicyclic groups such as cyclodo-decane. 

Newer polyamides also contain alicyclic groups. Of course, products derived from cyclohexane can occur in cis or trans configurations with very... 

The solubility of aromatic Pis could be enhanced by the introduction of kinks such as ether, bulky side groups, alicyclic groups [6], long flexible chains [7] meta- or ortho-oriented phenylene rings [8], cardo rings [9] and inclusion complex compounds [10]. Fluorination of... 

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