We were able to indentify the organic cage compound Hexamethylenetetramine (HMT; C₆H₁₂N₄) in the mixture of organic compounds resulting from our simulations of the ultraviolet irradiation of interstellar/cometary ice analogs. The identification was made using gas chromatography-mass spectrometry (GC-MS), infrared (IR) spectroscopy, and nuclear magnetic resonance (NMR). For example, the comparison of the infrared spectrum of our organic residues to that of an HMT standard show that all of the peaks of HMT are seen in the spectrum of the organic material made in our dense cloud simulation (click on the figure to obtain a larger image). This suggests that HMT, or molecules like it should be present on comets. The latest discovery mission (STARDUST) will go to collect comet material and return it to earth in ~2007, which will allow us to test this possibility.

The presence of HMT in our residues may have implications for the origin of life. For example, HMT may have been a source of formaldehyde and ammonia on the early Earth and when hydrolyzed in acidic solutions, it decomposes into a number of new compounds, including amino acids. To view a mechanism whereby HMT may be formed during ice irradiation, click here.

For more detailed information on our laboratory work on our work concerning HMT, see:

Bernstein, M. P., Sandford, S. A., Allamandola, L. J., & Chang, S. (1994). Infrared Spectrum of Matrix-Isolated Hexamethylenetetramine in Ar and H₂O at Cryogenic Temperatures. J. Phys. Chem. 98, 12206-12210.

Bernstein, M. P., Sandford, S. A., Allamandola, L. J., Chang, S., & Scharberg, M. A. (1995). Organic Compounds Produced by Photolysis of Realistic Interstellar and Cometary Ice Analogs Containing Methanol. Astrophys. J. 454, 327-344.