Kinetics of molecular encapsulation of 1-methylcyclopropene into alpha-cyclodextrin.
1-methylcyclopropene (1-MCP), an ethylene inhibiting regulator, is commercially available in the form of an inclusion complex with alpha-cyclodextrin (alpha-CD). In this study, molecular encapsulation of gaseous 1-MCP into aqueous alpha-CD was investigated in a closed, agitated vessel with a flat gas-liquid interface. Molecular encapsulation of gaseous 1-MCP by alpha-CD is a simultaneous two-step reaction which involves the aqueous dissolution of gaseous 1-MCP and the encapsulation of the dissolved molecules by alpha-CD. The kinetics and mechanism of molecular encapsulation were analyzed based on the depletion rate of 1-MCP in the headspace of the vessel. The encapsulation rates could be explained quantitatively by the gas absorption theory with a pseudo-first-order reaction between 1-MCP and alpha-CD. The negative value of the calculated apparent activation energy of encapsulation (-24.4 kJ/mol) implied the significant effect of exothermic aqueous dissolution of 1-MCP. An encapsulation temperature of 15 degrees C was optimal; at this temperature, the highest 1-MCP yield and best inclusion ratio of inclusion complex were obtained. Changes in the X-ray diffraction pattern suggested that the crystal lattice structure of alpha-CD was altered upon inclusion of 1-MCP.
Department of Biotechnology, Tottori University, Japan.
Tze Loon
TL
Neoh
Kousuke
K
Yamauchi
Hidefumi
H
Yoshii
Takeshi
T
Furuta
D016573:Agrochemicals / Q000737:chemistry; D002214:Capsules; D003521:Cyclopropanes / Q000737:chemistry*; D005740:Gases; D007700:Kinetics; D012996:Solutions; D013816:Thermodynamics; D014961:X-Ray Diffraction; D047391:alpha-Cyclodextrins / Q000737:chemistry*
D016573:Agrochemicals; D002214:Capsules; D003521:Cyclopropanes; D005740:Gases; D012996:Solutions; D047391:alpha-Cyclodextrins; C412563:1-methylcyclopropene; C032613:alpha-cyclodextrin