The temperature-dependent structure of alkylamines and their corresponding alkylammonium-alkylcarbamates.
In spite of the wide use of alkylamine (AA) surfactants, little attention has been paid to their spontaneous reactivity in air. Exposure of AA surfactants to CO(2) results in the formation of alkylammonium-alkylcarbamate (AAAC) molecular pairs. The effect of hydrocarbon chain length on the reactivity of AAs was followed by monitoring mass gain vs time under atmospheric conditions as well as in a saturated CO(2) environment. The rates of conversion to AAAC decreased with hydrocarbon chain length. Indexed powder X-ray diffractograms and the corresponding unit cells are presented for all phases of AAs and AAACs with chain lengths of 14, 16, and 18 carbons. Temperature-resolved powder X-ray diffraction of AAACs indicated anisotropic thermal expansion occurring exclusively along the a direction of the unit cell.
Belman
Nataly
N
Department of Materials Engineering and Ilse Katz Institute of Nanotechnology, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel.
Israelachvili
Jacob N
JN
Li
Youli
Y
Safinya
Cyrus R
CR
Bernstein
Joel
J
Golan
Yuval
Y
D000042:Absorption; D000478:Alkylation; D000588:Amines / Q000737:chemistry*; D002219:Carbamates / Q000737:chemistry*; D002245:Carbon Dioxide / Q000737:chemistry*; D015394:Molecular Structure; D033362:Powder Diffraction; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D013329:Structure-Activity Relationship; D013501:Surface-Active Agents / Q000737:chemistry*; D013696:Temperature; D044366:Transition Temperature; D014961:X-Ray Diffraction
D000588:Amines; D002219:Carbamates; D000644:Quaternary Ammonium Compounds; D013501:Surface-Active Agents; D002245:Carbon Dioxide