Calculation Method for Reaction Heat of Alkali Metals and Alcohol Solvents Based on Quantum Chemistry and Molecular Dynamics

Abstract

The present invention discloses a method for calculating the reaction heat of alkali metals and alcohol solvents based on quantum chemistry and molecular dynamics. By designing a reasonable reaction thermodynamics path and combining quantum chemistry calculations and molecular dynamics simulation methods, a method for calculating the reaction heat of alkali metals and alcohol solvents is proposed. The advantages of the present invention are as follows: Only based on a small amount of process data, it can quickly and accurately calculate the reaction heat of alkali metals and alcohol solvents. Compared with traditional calorimetry experiments, it has obvious advantages in terms of safety, speed and low cost, and provides a feasible technical approach for accurately obtaining the reaction heat data of alkali metals and alcohol solvents.

Description

Technical Field

[0001] The present invention relates to the field of reaction heat calculation in chemical production, and particularly to a method for calculating the reaction heat of alkali metals and alcohol solvents based on quantum chemistry and molecular dynamics. Background Art

[0002] Reaction heat data plays an important role in both chemical engineering design and chemical production. In chemical engineering design, the accuracy of reaction heat data has important guiding significance for heat balance calculation, heat energy utilization, and process calculation. In chemical production, because the substances involved in chemical processes are numerous, the processes are complex, and the conditions are harsh, accidents are more likely to occur compared with other industries. And runaway reaction heat release is an important factor leading to chemical accidents. Therefore, analyzing and evaluating typical exothermic reactions to obtain true and reliable reaction heat data is of great significance for guiding industrial practice and promoting the safety of chemical processes. The present invention takes the production process of alcohol metal compounds, that is, the reaction of alkali metals and alcohols, as the research object. This reaction has a fast reaction rate and a large heat release, and there will be a high heat accumulation in the production equipment in a short time. If these heats cannot be removed in time, it may damage the production equipment, and more seriously, it may cause a fire or explosion. Subsequently, accurately obtaining the reaction heat data of alkali metals and alcohols is crucial for guiding and ensuring the safe production of alcohol metal compounds.

[0003] In the laboratory, reaction heat data is generally obtained by measuring the change in heat in the reactor, and then determining the reaction heat. This requires considering as accurately as possible the heat flow through the reactor wall, the heat exchanged during the addition of reactants or solvents, and the heat accumulated due to temperature rise or fall. The measurement conditions are relatively harsh. However, the reaction of alkali metals and alcohols is violent, rapidly releasing a large amount of hydrogen and heat, resulting in a large error in the reaction heat measured by experimental methods, and often accompanied by certain safety hazards.

[0004] The method of computational simulation provides a possible technical approach to accurately obtain the reaction heat data of alkali metals and alcohols. Common calculation methods for reaction heat include group contribution method, bond energy calculation method, quantum chemistry calculation, molecular dynamics simulation method, etc. The basic principle of these methods is to calculate the energy difference between the products and the reactants to obtain the reaction heat. The group contribution method and the bond energy calculation method estimate the energies of the reactant and product molecules based on the types and quantities of groups in the compound and the types and quantities of chemical bonds, respectively. However, for alkali metal substances, due to the characteristics of electron delocalization, it is difficult to calculate the energy by dividing groups or chemical bonds. Quantum chemistry calculates the energy of molecules in a more accurate way, that is, by solving the Schrödinger equation describing the motion of electrons, fully considering the interactions between electrons and electrons, and between electrons and atomic nuclei. The calculation of metals usually has higher accuracy compared to the group contribution method and the bond energy calculation method. Among them, Density Functional Theory (DFT) is one of the most commonly used quantum chemistry methods, which is widely used in the calculation of organic reaction heat, and the reliability of its calculation results has been confirmed by corresponding experiments. At the same time, for the many-body system composed of atomic nuclei and electrons, the Molecular Dynamics (MD) simulation method calculates and simulates the motion process of atomic nuclei to obtain the structure and properties of the system. Numerous studies have proved that it plays an increasingly important role in the simulation of the thermodynamic properties of clusters, etc. Summary of the Invention

[0005] The present invention provides a method for calculating the reaction heat of alkali metals and alcohol solvents based on quantum chemistry and molecular dynamics. Aiming at the large errors in the measurement of the reaction heat of alkali metals and alcohols by existing reaction heat measurement means and the deficiency of certain potential safety hazards, by constructing a reasonable thermodynamic path and combining quantum chemistry and molecular dynamics simulation methods, the reaction heat of alkali metals and alcohol solvents is accurately calculated, which specifically includes the following steps:

[0006] Step 1. Enthalpy change of removing atoms from solid alkali metals Use programs such as Avogadro or Materials Studio to construct the crystal structure of solid alkali metals, and use LAMMPS, Materials Studio, CP2K, etc. for molecular dynamics simulation to obtain the average enthalpy value of atoms in solid alkali metals And the enthalpy value of alkali metal atoms in vacuum Difference

[0007]

[0008] Step 2. Enthalpy change of alkali metal atoms entering alcohol solvents Using quantum chemistry calculation software such as Gaussian or ORCA, the enthalpy values of alkali metal atoms in vacuum are calculated using density functional theory combined with an implicit solvent model and the enthalpy values of alkali metal atoms in an alcohol solvent environment of the difference

[0009]

[0010] Step 3: Enthalpy change ΔH3 of the reaction between alkali metal atoms and alcohol solvents: First, a liquid-phase alcohol system is constructed, and molecular dynamics simulations are carried out using classical molecular force fields or ab initio molecular dynamics methods. Sampling of the kinetic trajectories is performed to obtain alcohol cluster structures with different numbers of molecules. Subsequently, further optimization is carried out through density functional theory to determine the alcohol cluster structure with the lowest average energy, and its enthalpy value is calculated, thereby obtaining the average enthalpy value H of alcohol molecules 醇类 ; Then, the molecular structures of alcohol metal compounds and hydrogen are constructed, and using density functional theory, the enthalpy value H of alcohol metal compounds is calculated in an alcohol solvent environment 醇类金属化合物 , and the enthalpy value H of hydrogen is calculated in a solvent-free environment 氢气 , and finally the above enthalpy values and those in Step 2 are respectively substituted into Equation (3) to obtain ΔH3:

[0011]

[0012] Step 4: Enthalpy change ΔH4 of the complex formation of alcohol metal compound·alcohol cluster: First, a molecular dynamics simulation program is used to simulate the alcohol solution system of alcohol metal compounds, and the radial distribution functions and coordination numbers between alkali metal atoms, between alkali metals and oxygen atoms of alcohols are analyzed to determine the interaction range and coordination characteristics between alcohol metal compounds and alcohol molecules, and different alcohol metal compound·alcohol cluster structures are obtained accordingly; Subsequently, further optimization is carried out through density functional theory to determine the alcohol metal compound·alcohol cluster structure with the lowest energy, and the enthalpy value H of this cluster is calculated 醇类金属化合物·醇团簇 , and finally the average enthalpy value H of alcohol molecules in Step 3 醇类 and the enthalpy value H of alcohol metal compounds 醇类金属化合物 are substituted into Equation (4) together to obtain ΔH4:

[0013] ΔH4 = (H 醇类金属化合物·醇团簇 - mH 醇类金属化合物 - nH 醇类 ) / m (4)

[0014] In the formula, m represents the number of alcohol metal compound molecules in the alcohol metal compound·alcohol cluster, generally taking 1, and n represents the number of alcohol molecules in the cluster;

[0015] Step 5. Calculate the reaction heat ΔH of the solid alkali metal and the alcohol solvent, that is, substitute the enthalpy changes obtained from the above steps into Equation (5) for calculation respectively:

[0016]

[0017] Step 6. The reaction heat ΔH obtained according to the above steps can be used for the simulation calculation of the production process of products such as sodium alkoxide or potassium alkoxide, or as a parameter for actual production control and reactor design.

[0018] Optionally, in Step 1 above, calculate the average enthalpy value of the atoms in the alkali metal and including the following steps: use programs such as Avogadro or Materials Studio to construct the crystal structure of the solid alkali metal, optimize the crystal structure by methods such as first-principles molecular dynamics and classical molecular dynamics, and adopt periodic boundary simulation conditions and isothermal-isobaric ensemble, and calculate the average enthalpy value of the atoms in the alkali metal by performing simulations at the set reaction temperature and pressure Then calculate the enthalpy value of a single sodium atom in a vacuum environment according to Equation (6)

[0019]

[0020] where E is the energy of a single atom calculated using the molecular force field, k B is the Boltzmann constant, R is the molar gas constant, and T refers to the initial reaction temperature of the alkali metal;

[0021] Optionally, in the above steps, H 氢气 、H 醇类 、H 醇类金属化合物 、H 醇类金属化合物·醇团簇 The calculation of includes the following steps:

[0022] (a) Use quantum chemistry calculation software such as Gaussian or ORCA to optimize the conformations of each molecule using density functional theory, then perform vibrational analysis to obtain the thermodynamic correction quantity δH at the reaction temperature, and correct δH using the frequency factor; among them, the calculations of other atoms or molecules except the hydrogen molecule need to be performed under a suitable implicit solvent model;

[0023] (b) Use quantum chemistry calculation software such as Gaussian or ORCA to perform self-consistent calculations under a higher-level density functional theory method to obtain a more accurate electronic energy E ele ;

[0024] (c) Finally, calculate the enthalpy value H according to Equation (7):

[0025] H = E ele + δH (7)

[0026] Optionally, in the above step three, the most stable alcoholate (lithium)·alcohol cluster structure is determined by molecular dynamics simulation method and density functional theory, including the following steps:

[0027] (a) A cubic box is constructed using periodic boundary conditions. In the box, an alcohol solution model of the metal alcohol compound is built with a molecular ratio of metal alcohol compound: alcohol = 1:50. Subsequently, relaxation is carried out under the isothermal and isobaric ensemble (NPT), and then the system is equilibrated. Specifically, when using first-principles molecular dynamics, the relaxation time is not less than 50 ps and the equilibration time is not less than 200 ps; when using classical molecular dynamics, the relaxation time is not less than 2 ns and the equilibration time is not less than 10 ns;

[0028] (b) For the obtained system structure, first, taking the alkali metal atom as the cluster core, the interaction range of the alkali metal atoms in the cluster is obtained according to the radial distribution function (RDF) between the alkali metals, and based on this, the number m of metal alcohol compound molecules in the cluster is determined. Then, according to the radial distribution function between the alkali metal and the oxygen atom (alcohol), the number n of alcohol molecules in the cluster is determined, so as to collect the conformations of the metal alcohol compound·alcohol clusters that meet the conditions from the kinetic trajectory;

[0029] (c) The different sampled metal alcohol compound·alcohol cluster systems are optimized using a higher-precision functional to obtain the most stable, i.e., the lowest-energy, metal alcohol compound·alcohol cluster structure;

[0030] Optionally, in the above steps, the alkali metal is potassium or sodium, and the alcohol is methanol or ethanol;

[0031] Optionally, in the above step six, according to the reaction heat ΔH obtained in step five, it can be used in chemical process simulation software to simulate the actual production process in the initial development stage; or, combined with the production control system, by collecting control data, the material flow rate, reaction temperature and pressure, etc. are obtained, and after real-time calculation, a reaction heat curve is obtained. The reactor temperature is controlled by the reaction heat, thereby improving the product quality and even avoiding the occurrence of dangerous accidents; the reaction heat data can also be used as the design parameters of the reactor to meet the corresponding production needs.

[0032] Compared with the prior art, the present invention has the following advantages:

[0033] In view of the large errors in the existing reaction heat measurement methods for measuring the reaction heat of alkali metals and alcohols and the existing potential safety hazards, the present invention combines quantum chemical calculations and molecular dynamics simulations to accurately calculate the reaction heat of alkali metals (solid) and alcohols (liquid). The method established in the present invention only requires a small amount of process data and can quickly and accurately calculate the reaction heat of alkali metals and alcohol solvents. Compared with traditional calorimetry experiments, it has obvious advantages in safety, speed, and low cost. It can not only provide reliable data support for the safe production of alcohol metal compounds but also establish a paradigm for calculating the reaction heat of alkali metals and alcohols. In addition, the reaction heat calculation method established in the present invention can be used for online calculation of reaction heat. By collecting control data, obtaining material flow rates, reaction temperatures, pressures, etc., and obtaining a reaction heat curve after real-time calculation, it provides reliable support for the heat control of reaction heat. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 : Schematic diagram of the specific technical approach of the present invention;

[0035] Figure 2 : Schematic diagram of the most stable structure of ethanol clusters in the embodiment of the present invention;

[0036] Figure 3 : Schematic diagram of the radial distribution function and coordination number between sodium atoms and oxygen atoms of ethanol in the embodiment of the present invention;

[0037] Figure 4 : Schematic diagram of the most stable structure of sodium ethoxide·ethanol clusters in the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0038] The following further elaborates in detail the specific implementation manners of the present invention. However, the present invention is not limited to these implementation manners. Any improvement or substitution based on the basic spirit of this embodiment still falls within the scope protected by the claims of the present invention.

[0039] A method for calculating the reaction heat of alkali metals and alcohol solvents based on quantum chemistry and molecular dynamics takes the reaction of metallic sodium and ethanol solvent at a temperature of 65 °C as an example to calculate its reaction heat data, including the following steps:

[0040] Step 1. Calculate the enthalpy change when a single sodium atom escapes from solid sodium and enters a vacuum environment

[0041] First, use Avogadro software to construct the crystal structure of solid metallic sodium, and use LAMMPS as the molecular dynamics simulation program. The molecular force field uses the embedded atom method (EAM). Perform 5 ns of molecular dynamics simulation under the isothermal and isobaric ensemble (NPT) at a temperature of 65 °C to calculate the average enthalpy value of sodium atoms in the solid Next, calculate the enthalpy value of a single sodium atom in a vacuum environment according to Equation (1).

[0042]

[0043] Where E is the energy of a single sodium atom calculated using the molecular force field, and k B is the Boltzmann constant, R is the molar gas constant, and T is the initial reaction temperature of solid sodium metal, 65 °C;

[0044] Finally, the difference between the two can be obtained according to Equation (2). is 94.26 kJ / mol;

[0045]

[0046] Step 2: Calculate the enthalpy change when a single sodium atom enters an alcohol environment from a vacuum environment.

[0047] For a single atom, there is no need to optimize the structure and perform frequency analysis. Therefore, directly use the M06-2X functional method in the Minnesota functional series to perform self-consistent calculations under the triple-zeta polarization basis set, and calculate the electronic energy E of the sodium atom in the vacuum environment and ethanol solvent environment (implicit solvent model) respectively. ele . The thermodynamic correction quantity δH of the sodium atom can be calculated through Equation (3);

[0048]

[0049] Where k B is the Boltzmann constant, R is the molar gas constant, and T is the reaction temperature of 65 °C;

[0050] Next, calculate the enthalpy values of sodium in the vacuum environment and ethanol solvent environment according to Equation (4). and

[0051] H = E ele + δH (4)

[0052] Finally, the difference between the two can be obtained according to Equation (5). is 2.36 kJ / mol;

[0053]

[0054] Step 3: Calculate the enthalpy change ΔH3 when the sodium atom in ethanol solvent reacts with ethanol molecules to generate hydrogen and sodium ethoxide:

[0055] First, use the molecular dynamics simulation program to construct a cubic box with periodic boundary conditions, randomly distribute 100 ethanol molecules in the cubic box, select the COMPASS force field, and then perform relaxation for 2 ns under the isothermal and isobaric ensemble (NPT) with an equilibrium time of 10 ns;

[0056] Subsequently, by collecting different ethanol clusters, namely ethanol molecule n-mers (n = 2, 3, 4, 5, 6), and further using quantum chemistry calculation software, with the B3LYP functional method, under the 6-31G(d) basis set, combined with the implicit solvent model for optimization, and then using the M06-2X functional method for self-consistent calculation under the triple-zeta polarization basis set, the most stable conformations of different n-mers are obtained respectively, so as to obtain the average energy E of ethanol molecules 钠(平均) , select the lowest E among them 钠(平均) which corresponds to the ethanol cyclic hexamer structure (as Figure 2 shown);

[0057] Then, use the molecular simulation software to construct the molecular structures of hydrogen and sodium ethoxide, as well as the ethanol cyclic hexamer structure obtained through the above steps. Use the quantum chemistry calculation software, with the B3LYP functional method and the 6-31G(d) basis set, combined with the implicit solvent model, to further optimize the conformations of each molecule, and perform vibrational analysis at the reaction temperature of 65 °C. Then use the frequency factor to correct it to obtain its thermodynamic correction quantity δH. Among them, the hydrogen molecule is calculated in a solvent-free environment; subsequently, use the M06-2X functional method for self-consistent calculation under the triple-zeta polarization basis set to obtain a more accurate electronic energy E ele ; Next, calculate the enthalpy values H 乙醇钠 、H 氢气 、H 乙醇团簇(六聚体) of sodium ethoxide molecule, hydrogen, and ethanol cluster according to the above formula (4);

[0058] Finally, calculate the average enthalpy value H 乙醇团簇(六聚体) of ethanol molecules according to the obtained H 乙醇 , and then substitute the above enthalpy values into formula (6) respectively:

[0059]

[0060] to obtain ΔH3 as -102.22 kJ / mol;

[0061] Step 4: Calculate the enthalpy change ΔH4 for the complexation of sodium ethoxide and ethanol molecules to form sodium ethoxide·ethanol cluster:

[0062] First, using a molecular dynamics simulation program, a cubic box was constructed with periodic boundary conditions. Ten sodium ethoxide molecules and 500 ethanol molecules were randomly distributed in the cubic box. The COMPASS force field was selected, and then relaxation was carried out for 2 ns under the isothermal and isobaric ensemble (NPT), with an equilibrium time of 10 ns;

[0063] Through simulation, it was found that the interaction distance between sodium metals was relatively far. Therefore, the number m of sodium ethoxide in the sodium ethoxide·ethanol cluster was taken as 1. According to the radial distribution function (RDF) and coordination number between sodium atoms and oxygen atoms (ethanol), the number n of ethanol in the sodium ethoxide·ethanol cluster was approximately 8 (as Figure 3 shown). A certain number of sodium ethoxide·ethanol clusters, such as 50, were selected from the simulation trajectory. The eight ethanol molecules closest to the center of the sodium atom were retained, and the density functional method was further used to optimize the structures of these sodium ethoxide·ethanol clusters;

[0064] For structure optimization, a quantum chemistry calculation software was used. The B3LYP functional method and the 6-31G(d) basis set were used, combined with an implicit solvent model, to optimize different sodium ethoxide·ethanol cluster systems. Then, the M06-2X functional method was used for self-consistent calculation under the triple-ζ polarization basis set to obtain the most stable cluster structure with the lowest energy (as Figure 4 shown);

[0065] Finally, based on the obtained structure, the enthalpy value H of the sodium ethoxide·ethanol cluster was calculated using density functional theory 乙醇钠·乙醇团簇 , thereby obtaining the enthalpy change ΔH4:

[0066] ΔH4 = (H 乙醇钠·乙醇团簇 - mH 乙醇钠 - nH 乙醇 ) / m (7)

[0067] where m = 1, n = 8;

[0068] Through calculation, ΔH4 was obtained as -186.92 kJ / mol;

[0069] Step Five: Calculate the reaction heat ΔH of solid sodium metal with ethanol solvent, that is, according to the enthalpy changes obtained in Step One, Step Two, Step Three, and Step Four, substitute them into Equation (8) to calculate ΔH:

[0070]

[0071] The total enthalpy change ΔH of the reaction of solid sodium metal with ethanol solvent was obtained as -192.51 kJ / mol, and this reaction was an exothermic reaction.

Claims

1. A method for calculating the reaction heat of alkali metals and alcohol solvents based on quantum chemistry and molecular dynamics, characterized in that, It includes the following steps: Step 1: Construct the solid alkali metal crystal structure and use molecular dynamics simulation to calculate the average enthalpy value of atoms in the solid alkali metal and the enthalpy value of alkali metal atoms in vacuum difference Step 2: Calculate the enthalpy value of alkali metal atoms in vacuum using density functional theory combined with an implicit solvent model and the enthalpy value of alkali metal atoms in an alcohol solvent environment difference Step 3: First, construct a liquid-phase alcohol system, and perform molecular dynamics simulations using a molecular dynamics simulation program to sample the kinetic trajectories to obtain alcohol cluster structures with different numbers of molecules; Subsequently, it is further optimized by density functional theory to determine the alcohol cluster structure with the lowest average energy, and then the average enthalpy value H of the alcohol molecules is obtained. 醇类 Then, the molecular structures of the alcohol metal compounds and hydrogen are constructed, and the density functional theory is used to calculate the enthalpy value H of the alcohol metal compounds in an alcohol solvent environment. 醇类金属化合物 The enthalpy value H of hydrogen is calculated in a solvent-free environment. 氢气 Finally, the above enthalpy values and those in Step 2 are respectively substituted into Equation (3) to obtain ΔH3: Step 4: First, use the molecular dynamics simulation program to simulate the alcohol solution system of the metal alcohol compound, analyze the radial distribution function and coordination number between alkali metal atoms, between the alkali metal and the oxygen atom of the alcohol to determine the interaction range and coordination characteristics of the metal alcohol compound and the alcohol molecule, and sample the kinetic trajectory accordingly to obtain different metal alcohol compound·alcohol clusters; subsequently, further optimize through density functional theory to determine the structure of the metal alcohol compound·alcohol cluster with the lowest energy, and calculate the enthalpy value H of this cluster 醇类金属化合物·醇团簇 , and finally substitute the average enthalpy value H 醇类 of the alcohol molecule in Step 3 and the enthalpy value H 醇类金属化合物 of the metal alcohol compound into Equation (4) to obtain ΔH4: ΔH4 = (H 醇类金属化合物· alcohol cluster - mH 醇类金属化合物 - nH 醇类 ) / m (4) In the formula, m represents the number of alcohol metal compound molecules in the alcohol metal compound·alcohol cluster, and n represents the number of alcohol molecules in the cluster; Step 5: Calculate the reaction heat ΔH of the solid alkali metal and the alcohol solvent, that is, substitute the enthalpy changes obtained from the above steps into Equation (5) for calculation respectively: Step 6: The reaction heat ΔH obtained from the above steps is used for the simulation calculation of the production process of sodium alkoxide or potassium alkoxide products, or as a parameter for actual production control and reactor design.

2. The heat of reaction calculation method for alkali metals and alcohol solvents based on quantum chemistry and molecular dynamics according to claim 1, wherein In Step 1, use the Avogadro or Materials Studio molecular modeling program to construct the solid alkali metal crystal structure; In Step 1, Step 3, and Step 4, the molecular dynamics simulations use LAMMPS, Materials Studio, or CP2K software.

3. The heat of reaction calculation method for alkali metals and alcohol solvents based on quantum chemistry and molecular dynamics according to claim 1, characterized in that In Step 1, calculate the average enthalpy value of atoms in solid alkali metals and the enthalpy value of alkali metal atoms in vacuum Specifically, it includes: optimizing the crystal structure, adopting periodic boundary simulation conditions and an isothermal-isobaric ensemble, and calculating the average enthalpy value of atoms in alkali metals by performing simulations at the set reaction temperature and pressure Then, calculate the enthalpy value of a single sodium atom in a vacuum environment according to Equation (6) where E is the energy of a single atom calculated using a molecular force field, k B is the Boltzmann constant, R is the molar gas constant, and T refers to the initial temperature of the alkali metal.

4. The heat of reaction calculation method for alkali metals and alcohol solvents based on quantum chemistry and molecular dynamics according to claim 1, characterized in that, H 氢气 、H 醇类 、H 醇类金属化合物 、H 醇类金属化合物·醇团簇 The calculation of (a) Use Gaussian or ORCA quantum chemistry calculation software to optimize the conformations of each molecule using density functional theory, then perform vibrational analysis to obtain the thermodynamic correction quantity at the reaction temperature, and correct the thermodynamic correction quantity using the frequency factor; (b) Perform self-consistent calculations using Gaussian or ORCA quantum chemistry calculation software under the density functional theory method to obtain a more accurate electronic energy E ele ; (c) Finally, calculate the enthalpy value H according to Equation (7): H = E ele + δH(7) Among them, δH is the thermodynamic correction quantity corrected in Step (a).

5. The heat of reaction calculation method for alkali metals and alcohol solvents based on quantum chemistry and molecular dynamics according to claim 4, characterized in that In Step (a), the calculations of other atoms or molecules except hydrogen molecules need to be carried out under an implicit solvent model.

6. The heat of reaction calculation method for alkali metals and alcohol solvents based on quantum chemistry and molecular dynamics according to claim 1, characterized in that The alkali metal is potassium or sodium, and the alcohol is methanol or ethanol.

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