Hydrogen bonding amines with water

Solubility in water Because of hydrogen bonding, amines with low molecular masses (four or less carbon atoms) are completely miscible with water. The solubility of an amine decreases as the number of carbon atoms increases. 

The close similarity between the structures of the amine phosphate and the final product of the reaction of the amine phosphate with metal (Zn2+) is shown in Fig. 7.24. The amine phosphate consists of a hydrogen-bonded network with water molecules and resembles the loosely hydrogen-bonded structures involved in the synthesis of aluminosilicates. The mechanism of formation of the initial ladder phosphate can be understood in terms of the displacement of the water molecules from the amine phosphate by the Zn2+ ions. 

Many LFe "(/u-0)(//-02CR)2Fe" L complexes have terdentate, triazamacrocyclic, or triazatri-podal ligands L. Examples include species with L = HB(pz)3, R = Me with L = tacn, R = Me with L = bis(2-benzimidazolylmethyl)amine, R = Me, Ph with L = A, A -bis(2-ethyl-5-methylimidazol-4-ylmethyl)aminopropane (213X R = Ph with L= Af-alkyl-Af,Af-bis(2-pyridyl-methyl)amine, alkyl = Me, Bz, adamantyl for R = Ph, also several other R for alkyl = Me and with L = bis((l-methylimidazol-2-yl)methyl)amine (214), R = Ph. In this last case hydrogen-bonding between lattice water and -oxo in the hydrated form results in a significant decrease in... 

The removal of H20 from the system shifts the reversible equilibrium to the hydrogen-bonded amine on the left, with a chemical shift of 25 - 27 ppm. The addition of H20 shifts the equilibrium to the hydrated Brdnstedt complex, having a chemical shift of 21 - 22 ppm. From the relative pK, values of the surface silanols (5.0 - 9.5) and the water (14), it is clear that the proton will be abstracted from the surface rather than from the adsorbed water molecule. 

Hydrophilic molecules are composed of ions (such as sulphonate, sulphate, carboxylate, phosphate and quaternary ammonium), polar groups (such as primary amines, amine oxides, sulphoxides and phosphine oxide) and non-polar groups with electronegative atoms (such as oxygen atom in ethers, aldehydes, amides, esters and ketones and nitrogen atoms in amides, nitroalkanes and amines). These molecules associate with the hydrogen bonding network in water. 

Figure 2). The layers in III are stacked along the b axis in an ABAB fashion and are held together by hydrogen bonding interactions with the triprotonated amine and water molecules. 

Bis(thiosemicarbazide)nickel(II) forms charge augmented double hydrogen-bonded chains with 1,4-terephthalate and trans-fumarate anions, which are further linked into sheets by hydrogen bonds between the N-H- -O units. The methylation of the primary amine disrupts these interactions markedly so that hydrogen-bonded sheets result, involving now molecules of water. ... 

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