A cyclic imine intermediate in the in vitro metabolic conversion of 1,6-diaminohexane to 6-aminohexanoic acid and caprolactam

Toxicity of hexamethylenediamine

Hexamethylendiamine (HMDA; CAS No. 124-09-4; 6055-52-3 for the dihydrochloride salt) is moderately toxic following acute doses/exposures with oral lethal doses in rats ranging from 750 to 1500 mg/kg. HMDA is extremely irritating to the skin and eyes and is not a sensitizer in guinea pigs. Repeated exposure inhalation studies have defined the upper respiratory tract to be the first target of HMDA. The irritation seen is proportional to the exposure concentration. Systemic damage is limited. Genetic testing is not extensive, but there is no indication of activity. HMDA is neither a developmental nor a reproductive toxin, but in one developmental study, the fetal No-observed-adverse-effect-level (NOAEL) was lower than that of the maternal animal. No carcinogenicity studies have been conducted. Documented human experience is limited, but indications of HMDA's irritative properties are found in the literature. HMDA does not persist or bioaccumulate in the environment. The chemical is not particularly toxic to fish and aquatic invertebrates but is quite toxic to algae. HMDA is rapidly absorbed and metabolized by the rat with little tissue storage.

Isotopically sensitive regioselectivity in the oxidative deamination of a homologous series of diamines catalyzed by diamine oxidase

The equivalence of aminomethylene groups in selected diamine substrates of diamine oxidase was exploited for the determination of intramolecular isotope effects. In the series of substrates, [1,1-2H2]-1,3-diaminopropane, [1,1-2H2]-1,5-diaminopentane, [1,1-2H2]-1,6-diaminohexane, [1,1-2H2]-1,7-diaminoheptane and [alpha,alpha-2H2]-4-(aminomethyl)benzylamine, the preference of the enzyme for reaction at the unlabeled methylene was found to vary from 1.45 to 10.5-fold. The observed partitioning ratios go through a minimum value with 1,5-diaminopentane, the best substrate of diamine oxidase of the compounds tested. The results suggest that fast substrates have less opportunity to reorient into alternate binding conformations while bound to the active site of the enzyme. On the other hand, diamine substrates tested that cannot exist in energetically favorable conformations with internitrogen distances of about 7-8 A showed larger intramolecular isotope effects.

Biological monitoring of isocyanates and related amines. II. Test chamber exposure of humans to 1,6-hexamethylene diisocyanate (HDI)

Five male subjects were exposed to 1,6-hexamethylene diisocyanate (HDI) atmospheres for 7.5 h. The exposures were performed in an 8 m3 stainless steel test chamber, and the HDI atmospheres were generated by a gas-phase permeation method. HDI in air was determined by an HPLC method utilizing the 9-(N-methylaminomethyl)-anthracene reagent, and by a continuous monitoring device (MDA 7100). The average air concentration was ca 25 micrograms/m3, and the inhaled dose of HDI for the different subjects was estimated at ca 100 micrograms. The related amine 1,6-hexamethylene diamine (HDA) was after acid hydrolysis of urine and plasma, determined as a heptafluorobutyric derivative, by glass capillary gas-chromatography and selected ion monitoring (SIM), in a chemical ionization mode using ammonia as reagent gas. The cumulated urinary excretion of HDA during 28 h was 8.0 to 14 micrograms, which corresponds to ca 11 to 21% of the inhaled dose of HDI. The urinary level of HDA, in samples collected immediately after the end of the exposures, was on average 0.02 mmol/mol creatinine (range 0.01-0.03 mmol/mol creatinine). The urinary elimination was rapid, and half-time (t 1/2), for the concentration of HDA in urine, showed an average of 1.2 h (range 1.1-1.4 h). No specific IgE and IgG antibodies to HDI were detected before and after provocation; nor were spirometry or bronchial reactivity changed immediately and 15 h after provocation. Analysis of HDA in hydrolysed urine, as a marker of short-time exposure to HDI, is proposed.