Diamine complexes

The easiest access to most benzyllithium, -sodium, or -potassium derivatives consists of the deprotonation of the corresponding carbon acids. Hydrocarbons, such as toluene, exhibit a remarkably low kinetic acidity. Excess toluene (without further solvent) is converted into benzyllithium by the action of butyllithium in the presence of complexing diamines such as A. Af.Af.jV -tetramethylethylenediamine (TMEDA) or l,4-diazabicyclo[2.2.2]octane (DABCO) at elevated temperatures1 a procedure is published in reference 2. 

The polyamide-hydrazide 7 was prepared by solution polymerization in anhydrous dimethylacetamide from terephthaloyl chloride and p-amino-benzhydrazide at ca. 10 °C. The polyamide 8 resulted from the polycondensation of m-phenylenediamine with isophthaloyl chloride at —20 °C, whereas 9 was prepared by the reaction of terephthaloyl chloride with the complex diamine l,3-bis(3-aminobenzamide)benzene at —20 °C. The water flux and salt rejection through these membranes were summarized in Table 5. The polyamide-hydrazide (7) membranes were prepared from polymer solutions containing 6 7% polymer (Mv 3 34,000) by casting on glass plates. The material was placed in an oven for 30 60 min and coagulated in deionized... 

The search for new chiral bases yielding even higher enantioselectivities has resulted in a number of more complex diamines as amide precursors. For example, Asami and coworkers designed the chiral base 14, which in the rearrangement of cyclohexene oxide 1 gave (,S )-cyclohexen-2-ol ((S)-2) in 89% ee (Scheme 10)2°. This result was a significant... 

The ee values have not been optimized. From today s knowledge improvements are possible by using a less polar solvent, not more than one equivalent of the complexing diamine, and keeping the deprotonation time as short as possible ( 5 min). Polar solvents, such as THF, cause rapid racemization [133,135, 141]. The same effect is observed when hthium is exchanged for potassium [133]. These results point to the importance of the incorporation of the Hthium... 

An asymmetric hydrogen transfer of ketones was reported using chiral perfluorinated ligands in a 2-propanol/n-perfluooctane biphasic system. Several perfluorinated salen and diamine ligands were examined for the reaction catalyzed by the [Ir(COD)Cl]2 complex diamine 16 was found to be most effective (Scheme 20). The reaction was carried out at 70" C for 30 min and then the mixture was cooled to 0°C. The perfluorooctane solution was separated and used for the next reaction. The reactivity was almost the same as that of the first mn, and the enantioselectivity was higher (79% ee). Two further recyclings of the fluorous layer yielded the product with enantioselectivities up to 59% ee, but a decrease in activity was observed. 

The products are ohgomeric to high polymers with DP values ranging from 10 to 1,000. Yields ranged from about 10 to over 90%. A wide range of diamines were employed including simple aliphatic diamines such as 1,6-diaminohexane, simple aromatic diamines such as p-phenylenediamine, to more complex diamines such as adenine, 2,6-diamino-8-purinol, 4,4 -diaminodiphenylsulfon, Zineb, and 2,4-diamino-5(3,4-dimethoxybenzil)pyrimidine. 

This chapter is focused on madangamines, a small group of complex diamine alkaloids Isolated from marine sponges of the order Haplosclerlda, and covers their Isolation, characterization, biogenesis, biological activity, and synthesis. Structurally, madangamines are pentacyclic alkaloids with an unprecedented skeletal type. 

Figure 13, Lithium dialkylaminoborohydrides in the synthesis of complex diamines and simple aliphatic amines.

Table 3.1 summarises the influence of the diamine ligands on the equilibrium constant for binding of 3.8c to the ligand-metal ion complex (K ) and the second-order rate constant for reaction of the ternary complex (ICjat) (Scheme 3.5) with diene 3.9. 

NMR signals of the amino acid ligand that are induced by the ring current of the diamine ligand" ". From the temperature dependence of the stability constants of a number of ternary palladium complexes involving dipeptides and aromatic amines, the arene - arene interaction enthalpies and entropies have been determined" ". It turned out that the interaction is generally enthalpy-driven and counteracted by entropy. Yamauchi et al. hold a charge transfer interaction responsible for this effect. 

The desired pyridylamine was obtained in 69 % overall yield by monomethylation of 2-(aminomethyl)pyridine following a literature procedure (Scheme 4.14). First amine 4.48 was converted into formamide 4.49, through reaction with the in situ prepared mixed anhydride of acetic acid and formic acid. Reduction of 4.49 with borane dimethyl sulfide complex produced diamine 4.50. This compound could be used successfully in the Mannich reaction with 4.39, affording crude 4.51 in 92 % yield (Scheme 4.15). Analogous to 4.44, 4.51 also coordinates to copper(II) in water, as indicated by a shift of the UV-absorption maximum from 296 nm to 308 nm. 

Heating Kemp s acid with appropriate aromatic diamines yields bis-imides with two convergently oriented carboxylic acid groups on the edges of a hydrophobic pocket. Dozens of interesting molecular complexes have been obtained from such compounds and can be traced in the Journal of the American Chemical Society under the authorship of J. Rebek, Jr., (1985 and later e.g. T. Tjivikua, 1990 B). 

Copolymers. There are two forms of copolymers, block and random. A nylon block copolymer can be made by combining two or more homopolymers in the melt, by reaction of a preformed polymer with diacid or diamine monomer by reaction of a complex molecule, eg, a bisoxazolone, with a diamine to produce a wide range of multiple amide sequences along the chain and by reaction of a diisocyanate and a dicarboxybc acid (193). In all routes, the composition of the melt is a function of temperature and more so of time. Two homopolyamides in a moisture-equiUbrated molten state undergo amide interchange where amine ends react with the amide groups. 

The order of melting transitions for the diphenyhnethane bismaleimides is surprising (Table 6) because the 4,4 -MDA-BMI melts lower (155—157°C) than the 3,3 -MDA-BMI. The tetra alkyl-4,4-MDA-BMI also melts around 150°C. The BMI based on the isomeric diphenylindane diamine (24) is very low melting because it is a complex blend of various isomers. 

Nylon resins are made by numerous methods (53) ranging from ester amidation (54) to the Schotten-Baumann synthesis (55). The most commonly used method for making nylon-6,6 and related resins is the heat-induced condensation of monomeric salt complexes (56). In this process, stoichiometric amounts of diacid and diamine react in water to form salts. Water is removed and further heating converts the carboxylate functions to amide linkages. Chain lengths are controlled by small amounts of monofunctional reagents. The molten finished nylon resin can be dkectly extmded to pellets. 

In the absence of ammonia and the concentration of polyamines being > 20 p.M the production of sediments take place. Ethylene diamine reacts with Hg(II) in the form of diimide -HNRNH- to form the insoluble complex IHgHNRNHHgl. In the presence of ammonia the production of sediments having complex composition is also possible. Given concentration of K Hgl 1-2 mM, NaOH 60-120 mM and compai able amounts of ammonia and ethylene diamine the products of reactions ai e only the soluble green-coloured complexes, bearing ammonia in the form of nitride and ethylene diamine in the form of diimide. Those complexes ai e polymers, with their absorption spectmms being different from those of the similar polymeric ammonia complexes. 

Respiratory sensitizers Isocyanates proteolytic enzymes p-phenylene diamine complex salts of platinum cyanuric chloride. ... 

The ketimine of isophorone diamine is formed by reacting it with methyl isobutylketone, splitting off water in the process. When said ketimine is added to an isocyanate-terminated prepolymer based on IPDI, a semi-stable system is established with a pot life of several hours. The ketimine is a Schiff base and thus can react even in the absence of water. The complexities and advantages of this system are reviewed by Bock and Halpaap [75] ... 

Methylene dianiline is normally a very reactive diamine in the presence of diisocyanates. However, a sodium chloride complex that is relatively unreactive at room temperature is commercially available. When the complex is heated to 21°C, it activates to quickly cure the urethane [76]. 

Some instances of incomplete debromination of 5,6-dibromo compounds may be due to the presence of 5j5,6a-isomer of wrong stereochemistry for anti-coplanar elimination. The higher temperature afforded by replacing acetone with refluxing cyclohexanone has proved advantageous in some cases. There is evidence that both the zinc and lithium aluminum hydride reductions of vicinal dihalides also proceed faster with diaxial isomers (ref. 266, cf. ref. 215, p. 136, ref. 265). The chromous reduction of vicinal dihalides appears to involve free radical intermediates produced by one electron transfer, and is not stereospecific but favors tra 5-elimination in the case of vic-di-bromides. Chromous ion complexed with ethylene diamine is more reactive than the uncomplexed ion in reduction of -substituted halides and epoxides to olefins. ... 

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