Hexamethylenetetramine, structure

Hexamethyleneimine, N-nitroso-synthesis, 7, 518 Hexamethylenetetramine applications, 3, 529 degradative nitrosation, 3, 488 food preservative, 1, 411 quatemization, 3, 488 reactivity, 3, 487 88 structure, 2, 6 synthesis, 3, 509... 

The novolak resins themselves contain no reactive methylol groups and do not form cross-linked structures on heating. If, however, they are mixed with compounds capable of forming methylene bridges, e.g. hexamethylenetetramine or paraformaldehyde, they cross-link on heating to form infusible, thermoset structures. 

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... 

Normally the reaction Is useful for the conversion of alkyl halides to primary amines without concomitant formation of secondary amines.29 Treatment of polymer 17 with hexamethylenetetramine in a mixture of ethanol/THF afforded an insoluble resin. Using diazabicyclooctane (DABCO), we demonstrated that the reaction could be limited to attack by a single nitrogen in a multifunctional amine, so we did not anticipate crosslinking via bis-quat salt formation. Hydrolysis of 2 with anhydrous HC1 in ethanol generated free amino groups as evidenced by a positive ninhydrin test, but quantitative hydrolysis could not be achieved and the product remained insoluble. One would have expected a simple bis-quat to hydrolyse and open the crosslinked structure. 

Working first with Polanyi, Weissenberg, and Brill, and later as the leader of the Textile Chemistry Section, Mark successively published papers on the crystal structures of hexamethylenetetramine, pentaerythritol, zinc salts, tin, urea, tin salts, triphenylmethane, bismuth, graphite, sulfur, oxalic acid, acetaldehyde, ammonia, ethane, diborane, carbon dioxide, and some aluminum silicates. Each paper showed his and the laboratory s increasing sophistication in the technique of X-ray diffraction. Their work over the period broadened to include contributions to the theories of atomic and molecular structure and X-ray scattering theory. A number of his papers were particularly notable including his work with Polanyi on the structure of white tin ( 3, 4 ), E. Wigner on the structure of rhombic sulfur (5), and E. Pohland on the low temperature crystal structure of ammonia and carbon dioxide (6, 7). The Mark-Szilard effect, a classical component of X-ray physics, was a result of his collaboration with Leo Szilard (8). And his work with E. A. Hauser (9, 10, 11) on rubber and J. R. 

In the third presentation, Mark, a leading expert in the area of structural analysis by X-ray crystallagraphy, expressed the opposite view. Comparing hexamethylenetetramine and cellulose, he proposed that cellulose consists of small units held together by forces "comparable by type and magnitude to the inner molecular forces". Mark concluded, "The whole crystallite appears as a large molecule" (61). 

Hexamethylenetetramine (HMTA) has important uses in modifying phenolic resin manufacture and is an intermediate in explosive manufacture. Although it is a complex three-dimensional structure, it is easily made by the condensation of formaldehyde and ammonia. 

Thus in a separate second part of this two-stage process a cross-linking agent is added and frirther reaction occurs. Although formaldehyde may be added, quite often hexamethylenetetramine is used, which decomposes to formaldehyde and ammonia. Occasional nitrogen bridges occur in the final structure of some phenolics made by this method. 

Treatment of duocarmycin segment A derivative 99 with hexamethylenetetramine (HMT) in TEA gives the novel ring structure 139 (Equation 38) <2000BMC1195>. 

It has been established that cyclotrimethylenetrinitrosoamine (II), a product of the nitrosation of hexamethylenetetramine, is oxidized with nitric acid (about 40%) to cyclonite (I). This confirms the structure of cyclonite. 

The chemistry of hexamethylenetetramine, or hexamine (70), has been reviewed thoroughly (B-61MI22000, p. 688,59HC(13)1, p.545,79S161). The discussion below summarizes these reviews. Hexamethylenetetramine has a symmetrical adamantane-like structure, and is quite stable. It is hydrolyzed by hot mineral acid to formaldehyde and the appropriate... 

Structures determined by X-ray analysis. Abbreviations pip = piperidine Mejpip = 2,6-dimethylpiperidine (CH NH = ethyleneimine (aziridine) (CH = hexamethylenetetramine (CH N-jH = dabconium ion. 

Therapeutic Function Antibacterial (urinary) Chemical Name Hexamethylenetetramine hippurate Common Name -Structural Formula ... 

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... 

In a molecular crystal, the idealized symmetry of the molecule is often not fully expressed in other words, the molecule occupies a site of lower point symmetry. For example, in the crystal structure of naphthalene, the CsHio molecule (idealized symmetry Z>2h) is located at a site of symmetry I. On the other hand, the hexamethylenetetramine molecule, (CH2)6N4, retains its T symmetry in the crystalline state. Biphenyl, C6H5 —C6H5, which exists in a non-planar conformation with a dihedral angle of 45° (symmetry >2) in the vapor phase, occupies a site of symmetry I in the crystalline state and is therefore completely planar. 

Adamantane, a structural analog of hexamethylenetetramine, crystallizes at room temperature in the cubic space group Fm3m with ac = 944.5 pm and Z = 4. The structure is disordered, not ordered in space group F43m (no. 216, multiplicity = 96) as described in a previous report. The cubic close-packed arrangement of (CH2)6(CH)4 is favored over the body-centered cubic structure... 

The molecular skeletons of adamantane, (CH2)6(CH)4, and hexamethylenetetramine, (CH2)6N4 (Fig. 20.4.1) constitute the characteristic structural units of diamondoid networks containing one and two kinds of four-connected nodes, respectively. If the rod is long, the resulting diamondoid network... 

Figures 20.4.4(a) and 20.4.4(b) illustrate the crystal structure of the 1 1 complex of tetraphenylmethane and carbon tetrabromide. The nodes comprise C(C6H5)4 and CBr4 molecules, and the each linking rod is the weak interaction between a Br atom and a phenyl group. The hexamethylenetetramine-like structural unit is outlined by broken lines. Figures 20.4.4(c) and 20.4.4(d) show the crystal structure of tetrakis(4-bromophenyl)methane, which has a distorted diamondoid network based on the hexamethylenetetramine building unit. If the synthon composed of the aggregation of four Br atoms is considered as a node, then two kinds of nodes (Br4 synthon and quatenary C atom) are connected by rods consisting of p-phenylene moeities.

In the crystal structure of [Ag C(4-C6H4CN)4 ]BF4 xPhNCh, the structural unit is of the hexamethylenetetramine type (Fig. 20.4.7). The nodes are Ag atoms and C(4-C6H4CN)4 molecules, and the rods are CN- -Ag coordination bonds. The void space is filled by the nitrobenzene guest molecules and BFJ ions. 

Hexamethylenetetramine-like structure unit in the diamondoid network of... 

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