Resistance, intramolecular

Silver(III), with a ds electronic configuration, forms only a limited number of stable compounds because of the inaccessibility of a suitable ligand framework to coordinatively bind the unusual, higher valent central metal while, at the same time, resisting intramolecular electron transfer. They are thermodynamically and kinetically unstable. 

The exhaustive hydroboration of Cig-hexaquinacene (810) has been investigated and the isomeric exo -triols 816 and 817 isolated Also, diketone 809 has been functionalized as in 818a and 818b, but these epoxides resisted intramolecular cyclization . ... 

S-layer ultrafiltration membranes (SUMs) are isoporous structures with very sharp molecular exclusion limits (see Section III.B). SUMs were manufactured by depositing S-layer-carrying cell wall fragments of B. sphaericus CCM 2120 on commercial microfiltration membranes with a pore size up to 1 pm in a pressure-dependent process [73]. Mechanical and chemical resistance of these composite structures could be improved by introducing inter- and intramolecular covalent linkages between the individual S-layer subunits. The uni-... 

Fig. 21 The variation of the balancing tunneling current of the four branches four electrodes monomolecular Wheatstone bridge connected as presented in (a). In (b), the dashed line is for the current intensity 7W (in absolute value) measured by the ammeter A and deduced from the standard Kirchoff laws calculating each molecular wire tunneling junction resistance of the bridge one after the other from the EHMO-ESQC technique. In (b), Hie full line is the same tunnel current intensity but obtained with the new intramolecular circuit rules discussed in Sect. 2. (c) The resistance of the branch used to balance the bridge as a function of its rotation angle. The minimum accessible resistance by rotation is 78 MQ for the short tolane molecular wire used here...

Microgels have been prepared from epoxy resins which were intramolecular-ly crosslinked by a polyalkylene polyamine/polycarboxylic acid for flexible, corrosion resistant coatings [354]. 

Intramolecular aldol condensation.1 This base can be effective for intramolecular aldol condensation of extremely hindered diketones that resist cyclization with the usual bases. 

A substantial intramolecular protective effect by phenyl groups in polymers is shown by the low G values for Hz and crosslinking in polystyrene (substituent phenyl) and in polyarylene sulfones (backbone phenyl), as well as many other aromatic polymers. The relative radiation resistance of different aromatic groups in polymers has not been extensively studied, but appears to be similar, except that biphenyl provides increased protection. Studies on various poly(amino acid)s indicate that the phenol group is particularly radiation resistant. 

The salicylimides (4.169) were found to be markedly more resistant to chemical hydrolysis than 4.166. These compounds were hydrolyzed exclusively at the distal amide bond, meaning that hydrolysis produced only sali-cylamide (4.170) and not salicylic acid. This behavior has been ascribed to steric hindrance by the 2-OH group. An intramolecular general base catalysis does not seem to be involved since, as stated, the salicylamides were less reactive than the corresponding benzamides. The rate of plasma-catalyzed hydrolysis of the A-acylsalicylamides was also dependent on the nature of... 

An unusual case of intramolecular competition (chemoselectivity, see Chapt. 1 in [la]) between ester and oxirane occurs in the detoxification of (oxiran-2-yl)methyl 2-ethyl-2,5-dimethylhexanoate (10.49), one of the most abundant isomers of an epoxy resin. The compound is chemically very stable, i.e., resistant to aqueous hydrolysis, but is rapidly hydrolyzed in cytosolic and microsomal preparations by epoxide hydrolase and carboxylesterase, which attack the epoxide and ester groups, respectively [129], The rate of overall enzymatic hydrolysis was species dependent, decreasing in the order mouse > rat > human, but was relatively fast in all tissues examined (lung and skin as portals of entry, and liver as a further barrier). In mouse and rat lung microsomes, ester hydrolysis was 3-4 times faster than epoxide hydration, whereas the opposite was true in human lung microsomes. 

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