Hexamethylenetetramine, complex with

Second only to sulfur-based systems, nitrogen complexes are relatively well represented in the structural literature with 41 complexes reported. Of these, 25 are with I2 as the electron acceptor, 11 are with the interhalogen IC1, three are with Br2, and two are with IBr. As expected, in every case the halogen bond forms between the nitrogen and the softest halogen atom, i.e., iodine, in all of the complexes except those with dibromine. Most N I2 complexes, and all N Br2, N IBr, and N IC1 complexes are simple adducts, mode A. Exceptions for the diiodine complexes include bridging mode (B) observed for diazines, such as pyrazine [86], tetramethylpyrazine [86], phenazine, and quinoxaline [87], and for 9-chloroacridine [89] and the 1 1 complex of diiodine with hexamethylenetetramine [144] and amphoteric bridging mode (BA) observed for 2,2 -bipyridine [85], acridine [89], 9-chloroacridine [89], and 2,3,5,6-tetra-2/-pyridylpyrazine [91]. The occurrence of both B and BA complexes with 9-chloroacridine, and of B and A complexes and an... 

Silver(I) complexes with polyamines also form molecular aggregates, thus hexamethylenetetramine yields 2D and 3D coordination networks,613 polymeric chains are obtained with diethylene-triamine, tris(2-aminoethyl)amine, or A,A -bis(aminoethyl)propane-l,3-diamine,426 and 2D networks are formed with thiocyanate and bridging polyamines.61... 

N-Donor Ligands. CrOa forms a 1 1 complex with hexamethylenetetramine, the i.r. and electronic spectra of which indicate that the metal has a pseudo-tetrahedral (C3J environment. ... 

Hydrogen peroxide is also complexed with hexamethylenetetramine, industrially prepared from formaldehyde and ammonia, which advantageously replaces DABCO. This... 

The solvent influences on the complex formation and stability have been reviewed by Golub et al.194 Several monomeric complexes of Hg(SCN)2 with N, O, P, As and S donor ligands are known with terminal Hg—SCN bonds.224-2 Some thiocyanate-bridged dimeric complexes of mercury(II) are also known.225,226 Recently the isolation of a mercury(II) thiocyanate complex with hexamethylenetetramine with exclusively N-bonded SCN groups has been published (Figure 9).233 The compounds (CH2)6N4-Hg(SCN)2 and (CH2)6N4-2Hg(SCN)2 exhibit covalently bonded Hg—s.394,595... 

Hexamethylenetetramine forms both 1 1 and 2 1 complexes with nickel(n) iodide.64 Only the nitro-isomer of [NiL(N02)]BPh4,Me0H [L = Et2N(CH2)2-NH(CH2)2NEt2] has been isolated.464 The structure of [NiLCl]Cl [L = (78)] is square pyramidal with the four amine donors coplanar and the nickel slightly out of plane towards the apical chlorine. The ionic chloride is hydrogen-bonded to the cation... 

Triazaphosphaadamantane forms complexes with phenol, catechol, resorcinol, and hydroquinone. These compounds are similar to those formed by hexamethylenetetramine, and were proposed as intermediates for the preparation of Bakelite-type resins (76MI1). 

The pH of coloured solutions is often stabilized by means of suitable buffers. Tartrate, citrate, phosphate and phthalate solutions are usually avoided since they can bind many metals in stable complexes. Acetate solutions are often used, although they also can form complexes with some metals ie.g., Al, Be). Acetate buffers may be replaced by hexamethylenetetramine buffers. 

Arch. Pharm. 288, 583 (1955). Forms a complex with hexamethylenetetramine which may be used to separate it from methyl ar bu tin -... 

Sulfoxides. The oxidation of sulfides with the bromine-hexamethylenetetramine complex is a rapid and high-yielding process (7 examples, 91-98%). 

Fig. 7.13. Schematic drawing of crystal packings cage-type observed in the fi-CyD complex with hexamethylenetetramine (A), head-to-head channel-type observed in the a-CyD complex with iodine-iodide (B), and layer-type observed in the a-CyD complex with p-nitrophenol (C).

An alloy of chromel containing Ni, Fe, and Cr was analyzed by a complexation titration using EDTA as the titrant. A 0.7176-g sample of the alloy was dissolved in ITNOa and diluted to 250 mb in a volumetric flask. A 50.00-mb aliquot of the sample, treated with pyrophosphate to mask the Fe and Cr, required 26.14 mb of 0.05831 M EDTA to reach the murexide end point. A second 50.00-mb aliquot was treated with hexamethylenetetramine to mask the Cr. Titrating with 0.05831 M EDTA required 35.43 mb to reach the murexide end point. Einally, a third 50.00-mb aliquot was treated with 50.00 mb of 0.05831 M EDTA, and back titrated to the murexide end point with 6.21 mb of 0.06316 M Cu +. Report the weight percents of Ni, fe, and Cr in the alloy. 

Hexamethylenetetramine. Hexa, a complex molecule with an adamantane-type stmcture, is prepared from formaldehyde and ammonia, and can be considered a latent source of formaldehyde. When used either as a catalyst or a curative, hexa contributes formaldehyde-residue-type units as well as benzylamines. Hexa [100-97-0] is an infusible powder that decomposes and sublimes above 275°C. It is highly soluble in water, up to ca 45 wt % with a small negative temperature solubiUty coefficient. The aqueous solutions are mildly alkaline at pH 8—8.5 and reasonably stable to reverse hydrolysis. 

Resol resins thermoset on heating and are used for adhesives. Novolacs require a further source of formaldehyde in the form of hexamethylenetetramine to produce molding powders. Phenolic moldings are resistant to heat, chemicals, and moisture with good electrical and heat insulation qualities. Complex phenols from, e.g., cashew-nut shell liquid, are used in making brake... 

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