CO2 clustering of 1-decanol and methanol in supercritical fluids by C-13 nuclear spin-lattice relaxation
CO2 clustering of 1-decanol and methanol in supercritical fluids by C-13 nuclear spin-lattice relaxation
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DOI：
10.1021/jp9640484
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发表时间：
1997-04-10
影响因子：
3.3
通讯作者：
Grant, DM
中科院分区：
文献类型：
--
作者：
Bai, S;Taylor, CMV;Grant, DM
蓝宝石高压NMR池，能够独立地控制样品的压力，温度和浓度，用于测量C-13自旋晶格弛豫时间的碳1，5，和9的1-癸醇在致密的二氧化碳中在80和200大气压之间的压力。这些NMR实验，进行了沿着四个等温线之间的288和348 K，提供松弛数据为1-癸醇在液体和超临界流体CO2。讨论了1-癸醇中碳原子1、5和9以及该混合物中二氧化碳中碳原子核的自旋-晶格弛豫机制。弛豫数据进行了分析，使用修改后的斯托克斯-爱因斯坦-德拜方程，连同AK模型，假定形成的CO2团簇与1-癸醇分子在CO2-癸醇混合物在超临界和近临界液体密度。这种CO2团簇形成与甲醇分子也检测到在早期的弛豫测量在CO2-甲醇混合物在可比的密度。可能的溶剂集群梯度沿着的脂肪链在1-癸醇在稠密的CO2也提出了建议。
A sapphire high-pressure NMR cell, capable of independently controlling sample pressure, temperature, and concentration, is used to measure C-13 spin-lattice relaxation times for carbons 1, 5, and 9 of l-decanol in dense carbon dioxide at pressure between 80 and 200 atm. These NMR experiments, carried out along four isotherms between 288 and 348 K, provide relaxation data for l-decanol in liquid and supercritical fluid CO2. The nuclear spin-lattice relaxation mechanisms for carbons 1, 5, and 9 of l-decanol as well as for the carbon nucleus in carbon dioxide of this mixture are discussed. The relaxation data are analyzed using a modified Stokes-Einstein-Debye equation, together with an AK model, that postulates the formation of CO2 clusters with the l-decanol molecule in CO2-decanol mixture at supercritical and near-critical liquid densities. Such CO2 cluster formation with methanol molecules was also detected in earlier relaxation measurements in CO2-methanol mixtures at the comparable densities. Possible solvent clustering gradients along the aliphatic chain in l-decanol in dense CO2 are also suggested.