| Hexamethylenetetramine | |
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1,3,5,7-Tetraazatricyclo[3.3.1.13,7]decane |
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Other names
Hexamine; Methenamine; Urotropine; 1,3,5,7- tetraazaadamantane, Formin, Aminoform |
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| Identifiers | |
| CAS number | 100-97-0 |
| PubChem | 4101 |
| ChemSpider | 3959 |
| UNII | J50OIX95QV |
| EC number | 202-905-8 |
| KEGG | D00393 |
| MeSH | Methenamine |
| ChEBI | CHEBI:6824 |
| ChEMBL | CHEMBL1201270 |
| Jmol-3D images | Image 1 |
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| Properties | |
| Molecular formula | C6H12N4 |
| Molar mass | 140.186 g/mol |
| Density | 1.33 g/cm³ (at 20 °C) |
| Boiling point |
280 °C (sublimes) |
| Solubility in water | 85.3 g/100 mL |
| Hazards | |
| Main hazards | Highly flammable, harmful |
| Autoignition temperature |
410 °C (770 °F) |
| (verify) (what is: /?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
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| Infobox references | |
Hexamethylenetetramine is a heterocyclic organic compound with the formula (CH2)6N4. This white crystalline compound is highly soluble in water and polar organic solvents. It has a cage-like structure similar to adamantane. It is useful in the synthesis of other chemical compounds, e.g. plastics, pharmaceuticals, rubber additives. It sublimes in a vacuum at 280 °C.
The compound was discovered by Aleksandr Butlerov in 1859.[1][2][3]
Contents |
Hexamethylenetetramine is prepared by the reaction of formaldehyde and ammonia.[4] The reaction can be conducted in gas-phase and in solution.
The molecule has a symmetric tetrahedral cage-like structure, similar to adamantane, whose four "corners" are nitrogen atoms and "edges" are methylene groups. Although the molecular shape defines a cage, no void space is available at the interior for binding other atoms or molecules, unlike crown ethers or larger cryptand structures.
The molecule behaves like an amine base, undergoing protonation and N-alkylation.
The main use of hexamethylenetetramine is in the production of powdery or liquid preparations of phenolic resins and phenolic resin moulding compounds, where it is added as a hardening component. These products are used as binders, e.g. in brake and clutch linings, abrasive products, non-woven textiles, formed parts produced by moulding processes, and fireproof materials.[4]
As the mandelic acid salt (generic methenamine mandelate tablets, USP [1]) it is used for the treatment of urinary tract infection: hexamethyltetramine ("methenamine") decomposes at an acid pH to formaldehyde and ammonia, and the formaldehyde is bactericidal; the mandelic acid adds to this effect. Urinary acidity is typically ensured by co-administering vitamin C (ascorbic acid) or ammonium chloride. Its use had temporarily been reduced in the late 1990s, due to adverse effects (notably chemically-induced hemorrhagic cystitis in overdose[2]), but its use has now been reapproved because of the prevalence of antibiotic resistance to more commonly used drugs. This drug is particularly suitable for long-term prophylactic treatment of urinary tract infection, because bacteria do not develop resistance to formaldehyde: however, it should not be used in the presence of renal insufficiency.
Methenamine silver stains are used for staining in histology, including the following types:
Together with 1,3,5-trioxane, hexamethylenetetramine is a component of hexamine fuel tablets used by campers, hobbyists, the military and relief organizations for heating camping food or military rations. It burns smokelessly, has a high energy density (30.0 MJ/kg), does not liquify while burning, and leaves no ashes.
Standardized 0.149 g tablets of methenamine (hexamine) are used by fire-protection laboratories as a clean and reproducible fire source to test the flammability of carpets and rugs.[5]
The explosives RDX, HMX, and HMTD can be derived from hexamethylenetetramine.
Hexamethylene tetramine or Hexamine is also used as a food additive as a preservative (INS number 239). It is approved for usage for this purpose in the EU,[6] where it is listed under E number E239, however it is not approved in the USA or Australia and New Zealand.[7]
Hexamethylenetetramine is a versatile reagent in organic synthesis. It is used in the Duff reaction (formylation of arenes),[8] the Sommelet reaction (converting benzyl halides to aldehydes),[9] and in the Delepine reaction (synthesis of amines from alkyl halides).[10]
Since 1990 the number of European producers has been declining. The French SNPE factory closed in 1990; in 1993, the production of hexamethylenetetramine in Leuna, Germany ceased; in 1996, the Italian facility of Agrolinz closed down; in 2001, the UK producer Borden closed; in 2006, production at Chemko, Slovak Republic, was closed. Remaining producers include INEOS in Germany, Caldic in the Netherlands, and Hexion in Italy. In the US, Eli Lilly and Company stopped producing methenamine tablets in 2002.[5]
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