A method for preparing deuterated iodomethane
By preparing deuterated iodomethane under iron powder catalysis, the problems of high reactant toxicity and low yield in the existing technology have been solved, and a method for preparing iodomethane with high yield and easy catalyst recovery has been realized.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ZHEJIANG UNIV OF TECH
- Filing Date
- 2023-08-16
- Publication Date
- 2026-05-05
AI Technical Summary
Existing methods for preparing iodomethane suffer from problems such as highly toxic reactants, low yield, difficulty in recovering acid catalysts, and inconvenient operation.
Deuterated methanol and elemental iodine were reacted under iron powder catalysis using an aprotic solvent and an inert atmosphere to prepare deuterated iodomethane via heterogeneous catalysis. After the reaction, elemental iodine was removed using copper powder and the catalyst was recovered.
A high-yield preparation of iodomethane was achieved, the catalyst was easy to separate and recover, the operation was simple, and the reagents were economical.
Abstract
Description
Technical Field
[0001] This invention relates to a method for preparing halogenated fine chemicals, specifically a method for preparing deuterated iodomethane. Background Technology
[0002] Deuterated iodomethane is a monoiodinated derivative of methane, with the molecular formula CH3I or MeI. It is a colorless, transparent liquid at room temperature, with a boiling point of 40.3℃ and a density of 2.28 g / cm³. 3 It is soluble in water and miscible with common organic solvents; it decomposes easily in light, and copper powder is often added to remove the elemental iodine produced by the decomposition of deuterated iodomethane.
[0003] In organic synthesis, iodomethane is commonly used as a methylating agent, frequently for the methylation of alcohols, phenols, ketones, esters, carboxylic acids, amino compounds, cyano compounds, nitro compounds, alkanes, sulfones, sulfoxides, imines, and hydrazones. Iodomethane is also an initiator of Grignard reactions, used to initiate Grignard reactions of inert haloalkanes.
[0004] Common methods for preparing iodomethane using existing technologies, such as using methanol and elemental iodine as raw materials and red phosphorus catalysis, are more suitable for secondary or tertiary alcohols as substrates, thus limiting the reaction with other alcohols as substrates.
[0005] Iodomethane is prepared by using methanol and potassium iodide as reactants under Lewis acid catalysis. This method has readily available reagents and is simple to operate. Hydroiodic acid is generated by the reaction of iodide and Lewis acid. However, the yield is low, with a maximum of only 40%.
[0006] This method involves preparing iodomethane from dimethyl sulfate and potassium iodide in the presence of calcium carbonate. Since dimethyl sulfate and iodomethane have significantly different boiling points, pure iodomethane can be obtained by simple distillation of the product followed by washing with saturated Na₂S₂O₃ and Na₂CO₃ solutions. While this method offers high yield and easy product separation, the reactant dimethyl sulfate is highly toxic, and the process is carried out under pressure, posing a potential hazard to operators. Summary of the Invention
[0007] To address the aforementioned technical problems in the existing technology, the present invention aims to provide a method for preparing iodomethane using a heterogeneous catalyst. This method overcomes the shortcomings of existing technologies, such as high reactant toxicity, low reaction yield, and difficulty in recovering acid catalysts. Instead, it provides a method that offers economical and convenient reagent sources, easy operation, high yield, and easy catalyst separation and recovery.
[0008] The technical concept of this invention is as follows: using deuterated methanol and elemental iodine as raw materials, a reaction is carried out under the catalysis of iron powder, and the product is collected from the reaction solution.
[0009] The technical solution adopted in this invention is as follows:
[0010] A method for preparing deuterated iodomethane includes the following steps:
[0011] 1) Add an aprotic solvent to the reactor, add iodine and iron powder catalyst in sequence under stirring at room temperature, replace the gas in the reactor with an inert gas atmosphere, stir and heat until condensation and reflux occur, add deuterated methanol, and react in the dark until the reaction is completed.
[0012] 2) Cool the reaction solution to room temperature, add deionized water for extraction and separation, filter the organic phase to recover the iron powder catalyst, add copper powder and stir to remove elemental iodine, add anhydrous calcium chloride to dry, filter, and collect the filtrate by vacuum distillation to obtain the target product deuterated iodomethane.
[0013] Further, the aprotic solvent in step 1) is selected from one of dimethyl sulfoxide, carbon tetrachloride, p-xylene, 1,3,5-trimethylbenzene, dioxane, and 2-methylimidazolinone; the volume of the aprotic solvent used is 5-20 times the volume of deuterated methanol.
[0014] Furthermore, the aprotic solvent is selected from carbon tetrachloride, and the volume of the aprotic solvent is 5-10 times that of deuterated methanol.
[0015] Furthermore, in step 1), the inert gas is nitrogen or argon.
[0016] Further, in step 1), the molar ratio of deuterated methanol to elemental iodine is 1:1-3.5, and the molar ratio of iron powder to elemental iodine is 0.5-2.5:1.
[0017] Furthermore, the molar ratio of deuterated methanol to elemental iodine is 1:2-2.5, and the molar ratio of iron powder to elemental iodine is 1.5-2:1.
[0018] Furthermore, in step 1), the reaction temperature is 70-120℃ and the reaction time is 5-120min.
[0019] Furthermore, the reaction temperature is 90-92℃, and the reaction time is 10-20 min.
[0020] Furthermore, the temperature of the vacuum distillation in step 2) is 35-60℃, and the distillation time is 10-20 min.
[0021] The beneficial effects of this invention are as follows: This invention provides a method for preparing deuterated iodomethane by catalysis with a heterogeneous catalyst, which can overcome the technical problems in the prior art such as high toxicity of reactants, low reaction yield, and difficulty in recovering acid catalysts. The reagents of this invention are economical and convenient to obtain, the operation is convenient, the reaction yield is high, and the catalyst is easy to separate and recover. Detailed Implementation
[0022] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto.
[0023] Example 1
[0024] Add 200 ml of carbon tetrachloride solvent to a 500 ml distillation flask equipped with a thermometer, a spherical condenser, and an electromagnetic stirrer. While stirring at room temperature, add 375.45 g of elemental iodine and 150 g of iron powder catalyst sequentially. Attach a PTFE tee to a blast-proof balloon and fill the reaction system with nitrogen gas, replacing the air in the system with nitrogen. Stir and heat to 70-72°C. Once the reaction solution shows signs of reflux, slowly add 30 ml of deuterated methanol using a sampler. Place the reaction apparatus in a dark, dry environment and react at this temperature for 30 minutes. Allow the reaction solution to stand and cool to... At room temperature, the upper layer of the reaction solution was placed in a separatory funnel, 200 ml of deionized water was added, the separatory funnel was inverted, and the mixture was shaken and the gas was released. The mixture was allowed to stand and separate into layers. The water in the organic layer was released. The above operation was repeated 3 times. The organic phase was removed and filtered to remove iron powder (which was collected and reused). An appropriate amount of copper powder was added to remove iodine. Anhydrous calcium chloride was added and dried. The collected filtrate was subjected to vacuum distillation at 45 °C. The distillate was collected in the first 15 minutes. The distillation operation was repeated three times. The conversion rate of deuterated methanol was 99.9% and the selectivity of deuterated iodomethane was 35.4% when measured by gas chromatography.
[0025] Example 2
[0026] Example 2 differs from Example 1 only in that the reaction temperature is adjusted to 100-102°C. The reaction results are: conversion rate of 99.9% and target product selectivity of 50.6%.
[0027] Example 3
[0028] The only difference between Example 3 and Example 1 is that the reaction temperature was adjusted to 110-112℃. The reaction results were: a conversion rate of 99.9% and a target product selectivity of 47.1%.
[0029] Example 4
[0030] Example 4 differs from Example 1 only in that the reaction temperature is adjusted to 90-92°C. The reaction results are: conversion rate of 99.9% and target product selectivity of 75.4%.
[0031] Example 5
[0032] Example 5 differs from Example 1 only in that the reaction temperature is adjusted to 90-92℃ and the reaction time is adjusted to 5 min. The reaction results are: conversion rate of 96.1% and target product selectivity of 75.1%.
[0033] Example 6
[0034] The only difference between Example 6 and Example 1 is that the reaction temperature was adjusted to 90-92℃ and the reaction time was adjusted to 20 min. The reaction results were: conversion rate of 98.6% and target product selectivity of 76%.
[0035] Example 7
[0036] The only difference between Example 7 and Example 1 is that "the amount of iodine used is 187.72g, and the reaction temperature is adjusted to 90-92℃". The reaction results are: conversion rate of 99.9% and target product selectivity of 49.3%.
[0037] Example 8
[0038] The only difference between Example 8 and Example 1 is that the reaction temperature was adjusted to 90-92℃ and the reaction time was adjusted to 60 min. The reaction results were: conversion rate of 99.9% and target product selectivity of 67.1%.
[0039] Example 9
[0040] The only difference between Example 9 and Example 1 is that the reaction temperature was adjusted to 90-92°C and the reaction time was adjusted to 90 min. The reaction results were: conversion rate of 99.9% and target product selectivity of 51.2%.
[0041] Example 10
[0042] The only difference between Example 10 and Example 1 is that the reaction temperature was adjusted to 90-92°C and the reaction time was adjusted to 120 min. The reaction results were: conversion rate of 99.9% and target product selectivity of 48.6%.
[0043] Example 11
[0044] The only difference between Example 11 and Example 1 is that the reaction temperature was adjusted to 90-92°C. The reaction results were: a conversion rate of 99.9% and a target product selectivity of 75%.
[0045] Example 12
[0046] The only difference between Example 12 and Example 1 is that "the amount of iron powder catalyst used is 75g, the reaction temperature is adjusted to 90-92℃, and the reaction time is 10min". The reaction results are: conversion rate of 99.9% and target product selectivity of 69.1%.
[0047] Example 13
[0048] Example 13 differs from Example 1 only in that "the carbon tetrachloride solvent is replaced with an equal volume of dioxane solvent, the reaction temperature is adjusted to 90-92°C, and the reaction time is 10 min". The reaction results are: conversion rate of 87.1% and target product selectivity of 13.1%.
[0049] Example 14
[0050] Example 14 differs from Example 1 only in that "carbon tetrachloride solvent was replaced with an equal volume of p-xylene solvent, the reaction temperature was adjusted to 90-92℃, and the reaction time was 10 min". The reaction results were: conversion rate of 67% and target product selectivity of 8.9%.
[0051] Example 15
[0052] Example 15 differs from Example 1 only in that "carbon tetrachloride solvent was replaced with an equal volume of 1,3,5-trimethylbenzene solvent, the reaction temperature was adjusted to 90-92°C, and the reaction time was 10 min". The reaction results were: conversion rate of 74.1% and target product selectivity of 13.6%.
[0053] Example 16
[0054] Example 16 differs from Example 1 only in that "the carbon tetrachloride solvent was replaced with an equal volume of 2-methylimidazolinone solvent, the reaction temperature was adjusted to 90-92°C, and the reaction time was 10 min". The reaction results were: conversion rate of 98.6% and target product selectivity of 32.5%.
[0055] Example 17
[0056] The only difference between Example 17 and Example 1 is that the reaction temperature was adjusted to 90-92°C and the reaction time was 10 min. The reaction results were: conversion rate of 98.9% and target product selectivity of 81%.
[0057] The contents described in this specification are merely an enumeration of the implementation forms of the inventive concept, and the scope of protection of this invention should not be regarded as limited to the specific forms described in the embodiments.
Claims
1. A method for preparing deuterated iodomethane, characterized in that, The preparation method includes the following steps: 1) Add an aprotic solvent to the reactor, add iodine and iron powder catalyst in sequence under stirring at room temperature, replace the gas in the reactor with an inert gas atmosphere, stir and heat until condensation and reflux occur, add deuterated methanol, and react in the dark until the reaction is completed. 2) Cool the reaction solution to room temperature, add deionized water for extraction and separation, filter the organic phase to recover the iron powder catalyst, add copper powder and stir to remove iodine, add anhydrous calcium chloride to dry, filter, and collect the filtrate by vacuum distillation to obtain the target product deuterated iodomethane. The aprotic solvent is selected from carbon tetrachloride; In step 1), the molar ratio of deuterated methanol to elemental iodine is 1:2-2.5, and the molar ratio of iron powder to elemental iodine is 1.5-2:
1. The reaction temperature is 90-92℃, and the reaction time is 10-20 min.
2. The method for preparing deuterated iodomethane as described in claim 1, characterized in that, The volume of the aprotic solvent used in step 1) is 5-20 times the volume of deuterated methanol.
3. The method for preparing deuterated iodomethane as described in claim 2, characterized in that, The volume of aprotic solvent used is 5-10 times that of deuterated methanol.
4. The method for preparing deuterated iodomethane as described in claim 1, characterized in that, In step 1), the inert gas is nitrogen or argon.
5. The method for preparing deuterated iodomethane as described in claim 1, characterized in that, The vacuum distillation in step 2) is carried out at a temperature of 35-60℃ for 10-20 minutes.