Alkyl Chain substituent

Physostigmine can be regarded as the methylcarbamate of a -amino-phenol, with an alkyl chain substituent in the o-position, relative to the amino-group. Stevens and Beutel, with this in mind, have prepared substances of the type p-RjRjjN, CO, O. CgHjR. NMCjX, where R is an alkyl radical, c.gi, isopropyl, in either the o or m-positioQ relative to the... 

The reported transition temperatures for a range of [RMIM] ionic liquids [6, 23-26, 46] are shown in Figure 3.1-5, with varying anion and alkyl chain substituent length. 

Table 6.23 AMINOALKYL INDOLES - N- ALKYL CHAIN SUBSTITUENTS [181]...

The solid state structure of the thiophosphorylated host depicted in Fig. 3 shows unambiguously the all inward orientation of the four P=S bonds [71]. As in the oxidized parent compound 12c, a solvent molecule (acetonitrile) is entrapped in the cavity of the host, and another one is embedded at the lower rim between the four long alkyl chain substituents. 

Figure 1 summarizes the chemical structures of the topochemically polymerizable 1,3-diene monomers providing stereoregular 1,4-trans polymer (Scheme 6) [ 16]. Most of the polymerizable monomers contain benzyl, naphthylmethyl, and long alkyl-chain substituents in their chemical structures. The (ZyZ)-, (E,Z)-, and ( , )-muconic and sorbic acids as well as the other diene carboxylic acids are used as the ester, amide, and ammonium derivatives. In contrast to this, the carboxylic acids themselves have crystal structures unfavorable for polymerization while they undergo [2-1-2] photodimerization, as has already been described in the preceding sections.

The majority of the early experiments were carried out on a variety of alkoxy-substituted phthalocyanines on the basis of which the following qualitative conclusions could be drawn (a) the intra-columnar mobility was relatively insensitive to the nature of the peripheral alkyl chain substituents which did however influence the mesomorphic properties (b) the mobility invariably decreased on... 

Lin et al. have studied variations in the chemical shifts for a variety of methyl-imidazolium salts with different alkyl chain substituents and Br, BF , and BF" anions [8]. They observed a high sensitivity in chemical shift (depending, among other factors, predominantly on the alkyl chain length) for the 2-proton in the imidazolium ring. The effect was most pronounced for the bromide salts. Additionally, they observed unexpected H/D exchange for the 2-proton. Today, these results can be interpreted as H-bonding effects, and of course the acidity of H2 comes to no surprise ([3,9] and references therein). 

Single crystals of thymine derivatives with long alkyl-chain substituents are photochemically reactive and undergo (2 + 2) photodimerisation to yield solely the trans-anti dimer. In solution, however, the photoreaction affords the usual four cycloadducts. Irradiation of the bis-thymine PNA dimer (142) brings about intramolecular cycloaddition to give the adduct (143) in 50% yield. The reaction is carried out in water using irradiation at 254 nm. The results from a study of the photochemical cycloaddition within the thymidilyl system (144) has been reported. Photoadducts have been obtained from the... 

In a related study, Hanabusa s group has incorporated long alkyl chain substituents onto similar melamine and barbiturate subunits [72]. They have demonstrated that a 1 1 mixture of 40 and 41 was capable of gelling N,N-dimethylformamide, chloroform, tetrachloromethane and cyclohexane at concentrations as low as 0.04 mol/ml (Fig. 22). The resulting stoichiometry of the system indicated that each 40 and 41 pair was able to gel approximately 460 molecules of cyclohexane. 

A number of ILs containing long alkyl chain substituents have been reported to be surface active and are currently termed as IL-based siufactants [7]. In fact, the term IL-based surfactants is more precise than IL-siufactants, especially considering that the majority of the IL-based surfactants have melting points above 100°C. IL-based surfactants, which possess characteristics of cationic surfactants, undoubtedly constitute a new class of surfactant system. It must be considered that there is only a limited number of conventional cationic surfactants that have wide applicability in separation science. 

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