Ando catalytic synthesis of 2
(Institute of Applied Chemistry, Maoming, Maoming 525000)
Abstract: Ando catalyst, 2 – nitro Thiophene Ethylene. The optimum conditions are: catalyst loading per 30gAl2O3 load 15gKF, catalyst and 2 – thiophene mass ratio of 4.80:1 formaldehyde, nitro-methane and 2 – thiophene mass ratio of 1.09:1 formaldehyde, using methanol as a catalyst in the solvent , reaction temperature between 0 ~ 5 . Reaction time 1.4h, yield 95.91 percent.
Keywords: Ando catalyst; 2 – thiophenecarboxaldehyde; nitro methane; 2 – nitro-thiophene ethylene
Key words: TQ251.2 Document code: A Article ID :0367-
6358 (2007) 02-092-03 2 – nitro-thiophene ethylene synthesis of 2 – thiophene ethylamine Intermediate . And 2 – thiophene ethylamine is lipid-lowering drugs, platelet aggregation inhibitors, cardiovascular drugs diastolic, 5 – lipoxygenase inhibitors and a variety of antibiotics and other important biological activity of drugs Intermediate , Mainly used for synthesis of important cardiovascular disease drugs ticlopidine hydrochloride [1,2]. [3] reported that 2 – thiophene formaldehyde and nitromethane in the mass fraction of 36% sodium hydroxide solution under the action of the condensation reaction to get a yield of 82.3% of 2 – nitro-thiophene ethylene. Reaction carried out in alkaline solution, prone to Cannizzaro reaction, and liquid alkali catalyst reaction time is long, complicated post-treatment processes, environmental pollution and corrosion laboratory equipment shortcomings.
Ando catalyst that KF/Al2O3 reagents, in 1979 by the Yamawaki and Ando discover that it is the load in the Al2O3 KF as a base catalyst for organic reactions, can greatly improve the catalytic activity. Not only stronger than the original alkaline KF, and can simplify the experimental operation, a more moderate reaction conditions. The elimination of environmental hazards without delay, to develop green chemical industry today, KF/Al2O3 as the same time, both basic and nucleophilic nature of the new solid base catalyst, to study the various types of organic reactions is very significant [4, 5]. To KF/Al2O3 for the catalytic synthesis of 2 – nitro-thiophene ethylene domestic rarely reported. Have done some research on this, the catalyst for Ando reported synthesis of 2 – nitro-thiophene ethylene results. Synthetic routes:
1 experiment 1.1 Reagents and equipment
Alumina (chromatography with 100 ~ 200 projects); potassium fluoride, nitro methane, methanol, concentrated hydrochloric acid, ethanol, cyclohexane and acetonitrile were commercially available analytical pure reagents; thiophene formaldehyde made (content 90%). XT-4 binocular microscope melting point apparatus (Beijing Tyco Instrument Co., Ltd.); Nicolet550 infrared spectrometer Analyzer (American Nicolet Corporation); PE-240C elemental analyzer type (U.S. PE firm).
1.2 Ando Catalyst In eggplant-shaped flask
will be KF? 2H2O dissolved in a certain amount of distilled water, then add 30g of neutral Al2O3, with a Rotary Evaporator at 60 water bath to remove visible moisture on (no drop steamed) , then at 80 water bath, under a certain vacuum rotary 1.5h, shall be a white powdery solid Ando catalyst KF/Al2O3 [6].
1.3 Preparation of thiophene formaldehyde [3]
The N, N-dimethylformamide (DMF) and thiophene to three bottles while mixing, ice salt bath cooling, the slow accession POCl3, and keep stirring, the reaction liquid temperature control In the 15 ~ 20 ; dropwise After stirring at 20 for 1h, then heated to 80 ~ 95 stir back 4h, cool to room temperature after heating stopped. Under stirring and ice in the salt bath by adding ice water, adjusted with sodium hydroxide solution, after cooling pH 5 to 6, and then anhydrous ether extracted 3 times, the ether layers combined. After washing, drying by adding anhydrous sodium sulfate, filtered sodium, atmospheric pressure steam to the ether, vacuum distillation (82 / 0.099MPa), have 2 – thiophene formaldehyde, the yield was 89.9%
1.4 2 – Preparation of nitro-thiophene ethylene
Flask in 3 with 2 – thiophene formaldehyde, nitromethane and methanol. By mechanical stirring, ice salt bath cooling, slowly add the dissolved in methanol KF/Al2O3 catalyst After dropping to 0 ~ 5 at stirring 1.4h, and then adding a certain amount of 50% (by mass) of methanol, in the off rapidly with stirring into ice water in concentrated hydrochloric acid, precipitated a large number of yellow precipitation, filtration, washing, drained, may yellow solid. Crude product recrystallized with anhydrous ethanol, Activated Carbon Marking that is too yellow needle-like crystals.
2 Results and discussion 2.1 Catalyst loading on the yield of the product in accordance with the operation of 2 – thiophene formaldehyde 7.0g, nitro methane 7.63g, catalyst amount was 6.71g, the catalyst for the ethanol solvent, temperature to 0 ~ 5 conditions to 30gAl2O3 load KF, KF study of loading on the yield of product, results in Table 1.
Above table can be seen: from 2 – thiophene aldehyde 2 – nitro-thiophene ethylene, the catalyst loading on the yield impact, when the load reaches a certain value , but will increase the load KF 2 – nitro-thiophene ethylene production decreased. The reason is to increase the concentration of base load capacity will increase, which will help carry out the condensation reaction; but excessive concentrations can occur 2 – thiophene Cannizzaro reaction of formaldehyde. The experiment to determine the adsorption 15gKF per 30gAl2O3 catalyst suitable for the Ando catalyst loading.
2.2 catalyst solvent on the yield of the product
KF-catalyzed reaction of carrier-free multi-use DMF as solvent, in order to enhance the activity of KF. Ando catalytic activity much higher than the carrier-free KF, but the solvent is still essential. In the case of other conditions remain unchanged, by changing the catalyst solvent to investigate its effect on the yield. In the 2 – thiophenecarboxaldehyde 70g, nitromethane 7.63g, the same load of catalyst 9.86g, reaction temperature 0 ~ 5 , the catalyst to change the impact of solvent on the yield in Table 2.
Can be seen from Table 2, cyclohexane as solvent, 2 – nitro-thiophene highest rate of ethylene production, followed by methanol. Experiment with ethanol and methanol as solvent and its products lighter in color, melting point are in the range of 78 ~ 81 , while the yield of cyclohexane although slightly higher than methanol, but with its response to solvent that there will be oily liquid, allowing for deeper color, melting point 66 ~ 72 , purity is not high. Accordingly, the condensation reaction of methanol catalyst to determine the best solvent.
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