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首页> 外文期刊>The Journal of Chemical Physics >Infrared spectroscopy of methanol-hexane liquid mixtures. II.The strength of hydrogen bonding
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Infrared spectroscopy of methanol-hexane liquid mixtures. II.The strength of hydrogen bonding

机译：甲醇-己烷液体混合物的红外光谱。二，氢键强度

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The study by Fourier transform infrared attenuated total reflectance spectroscopy at 27 ℃ ofmethanol (MeOH) and hexane mixtures is presented. In the 0-0.25 and 0.75-1.00 molar fractions,the mixtures form homogeneous solutions, whereas from 0.25 to 0.75, the mixtures areinhomogeneous forming two phases. These mixtures have the near 3300 cm~(-1)OH stretch band onlyslightly displaced throughout the whole concentration range indicating very little variation in theH-bonding condition. This result is very different from that of MeOH in CCl_4where the OH stretchbands are scattered in a wide frequency range. Factor analysis applied to the MeOH/hexane spectragave seven principal factors (one hexane and six methanol factors) and retrieved their principalspectra and abundances. In the inhomogeneous region, the two phase volumes changed inverselywith concentration, but their factor compositions are invariable at 1:3 and 3:1 molar ratios. Five ofthe six principal methanol factors have the O–H and the C-O stretch bands situated near,respectively, 3310 and 1025 cm~(-1)with little displacement in the whole concentration range. Thesixth factor observed at 3654 cm~(-1)(full width at half height < 40 cm~(-1))was assigned to freemethanol OH by Max and Chapados [J. Chem. Phys. 128, 224512 (2008)]. This speciesconcentration is very low but constant at around 0.01M in the methanol range of 0.5-2.5M. Themain OH stretch bands (3300 cm~(-1))were simulated with six Gaussian components that wereassigned to different hydrogen-bonding situations. These form reverse micelles at low methanolconcentrations and micelles at high concentrations that persist in pure methanol. A very differentstate of affairs exists in MeOH in CCl_4where free OH groups are formed in almost all mixturesexcept in pure MeOH. Since hexane is a better model of a lipidic milieu than CCl_4, the results forMeOH/hexane give a better representation of the fate of alcoholic OH groups in such a milieu.
机译：提出了通过傅里叶变换红外衰减全反射光谱在27℃下甲醇（MeOH）和己烷混合物的研究。在0-0.25和0.75-1.00的摩尔分数下，混合物形成均相溶液，而在0.25-0.75之间，混合物不均匀，形成两相。这些混合物在整个浓度范围内只有3300 cm〜（-1）OH的伸缩带，只有很小的位移，表明H键的条件变化很小。此结果与CCl_4中的MeOH拉伸带分散在较宽的频率范围内的MeOH的结果非常不同。对MeOH /己烷光谱进行的因子分析得出七个主要因子（一个己烷和六个甲醇因子），并检索了它们的主要光谱和丰度。在不均匀区域，两相体积随浓度成反比，但它们的因子组成在摩尔比为1：3和3：1时不变。六个主要甲醇因子中的五个具有O–H和C-O伸缩带，分别位于3310和1025 cm〜（-1）附近，在整个浓度范围内几乎没有位移。 Max和Chapados将在3654 cm〜（-1）处观察到的第六个因子（半高全宽<40 cm〜（-1））分配给游离甲醇OH [J.化学物理128，224512（2008）]。该物质浓度非常低，但是在0.5-2.5M的甲醇范围内恒定在0.01M左右。用6个高斯分量模拟了主要的OH伸展带（3300 cm〜（-1）），这些高斯分量被分配给不同的氢键结合情况。它们在低甲醇浓度下会形成反胶束，而在高浓度下仍会存在纯甲醇中的高胶束。在CCl_4中的MeOH中存在非常不同的状态，其中除纯MeOH外，几乎所有混合物中都形成游离OH基。由于己烷是一种比CCl_4更好的脂质环境模型，因此MeOH /己烷的结果可以更好地表示这种环境中的醇羟基基团的命运。

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