首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Bond cleavage during isobutanol thermal decomposition and the breaking of C-C bonds in alcohols at high temperatures
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Bond cleavage during isobutanol thermal decomposition and the breaking of C-C bonds in alcohols at high temperatures

机译:高温下异丁醇热分解过程中的键裂解和醇中C-C键的断裂

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摘要

Isobutanol was thermally decomposed in a single pulse shock tube under conditions where chain processes were suppressed. The main reaction is the breaking of C-C bonds. Literature rate expressions, experimentally determined, are found in some cases to be in disagreement. The rate expressions for the decomposition processes at temperatures of 1090 to 1240 K and pressures of 1.5 and 6 atm are k(isobutanol → isopropyl + hydroxymethyl) + k(isobutanol → methyl + 1-hydroxypropyl-2) = 10~(16.7±0.3) exp(-41097 ± 750) s~(-1), where k(isobutanol → isopropyl + hydroxymethyl) = 10~(16.45 ±0.3) exp(-40910 ± 750/T) s~(-1) and k(isobutanol → methyl + 1-hydroxypropyl-2) = 10 ~(16.38±0.3) exp(-41560 ± 750/T) s~(-1). These values permit comparisons with recent estimates including those from ab initio calculations. A new procedure is presented that uses information on the kinetics of bond breaking reactions of alkanes and the effect of OH substitution to derive rate coefficients for similar reactions of alcohols. This leads to the following rate expression for the smaller alcohols, at temperatures of 1090 to 1240 K and pressures of 1.5 and 6 atm, k(ethanol → methyl + hydroxymethyl) = 10~(16.42±0.3) exp(-43496 ± 750 K/T) s~(-1), k(isopropanol → methyl + 1-hydroxyethyl) = 10~(16.54±0.3) exp(-42495 ± 750 K/T) s~(-1), k(n-propanol → ethyl + hydroxymethyl) = 10~(16.43±0.3) exp(-41696 ± 750 K/T) s~(-1), and k(n-propanol → methyl + 2-hydroxymethyl) = 10 ~(16.53±0.3) exp(-42945 ± 750 K/T) s~(-1). Extension of this approach to other alcohols is straightforward. The resulting correlations along with the data on dehydration of alcohols provide novel information of the kinetic stability of alcohols.
机译:在抑制链状过程的条件下,异丁醇在单脉冲激波管中热分解。主要反应是C-C键的断裂。在某些情况下,发现通过实验确定的文献费率表达方式不一致。在1090至1240 K的温度和1.5和6 atm的压力下分解过程的速率表达式为k(异丁醇→异丙基+羟甲基)+ k(异丁醇→甲基+ 1-羟丙基-2)= 10〜(16.7±0.3) )exp(-41097±750)s〜(-1),其中k(异丁醇→异丙基+羟甲基)= 10〜(16.45±0.3)exp(-40910±750 / T)s〜(-1)和k(异丁醇→甲基+ 1-羟丙基-2)= 10〜(16.38±0.3)exp(-41560±750 / T)s〜(-1)。这些值允许与最近的估计值进行比较,包括从头算的结果。提出了一种新的程序,该程序使用有关烷烃的键断裂反应动力学和OH取代作用的信息来推导类似醇反应的速率系数。对于较小的醇类,在1090至1240 K的温度和1.5和6 atm的压力下,以下速率表示为:k(乙醇→甲基+羟甲基)= 10〜(16.42±0.3)exp(-43496±750 K) / T)s〜(-1),k(异丙醇→甲基+ 1-羟乙基)= 10〜(16.54±0.3)exp(-42495±750 K / T)s〜(-1),k(正丙醇→乙基+羟甲基)= 10〜(16.43±0.3)exp(-41696±750 K / T)s〜(-1),k(正丙醇→甲基+ 2-羟甲基)= 10〜(16.53±0.3) )exp(-42945±750 K / T)s〜(-1)。将此方法扩展到其他醇类很简单。所得的相关性以及有关醇类脱水的数据提供了有关醇类动力学稳定性的新信息。

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