RU2711566C2 - Method of producing cyclopropane fullerene derivatives - Google Patents

Abstract

FIELD: chemistry.SUBSTANCE: invention relates to a method of producing cyclopropane fullerene derivatives. Invention can be used in production of semiconductor fullerene-containing materials. Method of producing phenyl-C61-butanoic acid methyl ester ([60]PCBM) or phenyl-C71-butanoic acid methyl ester ([70]PCBM) involves fullerene (C60, C70) interaction with benzoyl-butyric acid methyl ester tosylhydrazone in presence of base in medium of organic solvent at high temperature and while stirring, where the process is carried out in the presence of potassium carbonate, pyridine and 1,2-dichlorobenzene, with equimolar ratio of tosylhydrazone and fullerene, followed by cooling the mixture, filtering, boiling with reflux condenser, concentration on a rotary evaporator and purification by column chromatography.EFFECT: objective of the invention is to simplify the process, reduce consumption of expensive reagents, accelerate the process while increasing the yield of the end product.1 cl, 8 dwg, 4 ex

Description

The invention relates to a method for producing cyclopropane derivatives of fullerenes. Cyclopropane derivatives of fullerenes and, in particular, fullerene-containing materials [60] RSVM and [70] RSVM, shown in Figure 1, are actively used as n-type semiconductor materials in organic solar cells. The light conversion efficiencies of the best photovoltaic devices based on composites of fullerene derivatives [60] RSVM, [70] RSVM and conjugated polymers reach 10-11% [K.N. Park, Y. An, S. Jung, H. Park and C. Yang, Energy Environ. Sci., 2016, 9, 3464-3471; Z. Wang, X. Xu, Z. Li, K. Feng, K. Li, Y. Li and Q. Peng, Advanced Electronic Materials, 2016, 2, 1600061].

An analogue of the proposed method for producing cyclopropane derivatives of fullerenes is the previously described method for the synthesis of fullerene-containing material [60] RSVM [R. Kumar, S. Naqvi, N. Gupta, S. Chand, RSC Advances, 2014, 4, 15675]. In the work, Kumar et al proposed to use triethylamine and methylene chloride to generate the intermediate diazocompound, which eliminated the inert atmosphere (Figure 2).

Subsequent addition of a solution of fullerene C ₆₀ in 1,2-dichlorobenzene to a solution of the diazocompound in methylene chloride with triethylamine and stirring at a temperature of 75 ° C for 18 hours led to the formation of a fulleroid, which then is boiled in 1,2-dichlorobenzene isomerized to the target product . The product yield after purification using column chromatography is 38-40%. The formation of by-products, the relatively low yield of the target product and the reaction time (at least 20 hours) are the main disadvantages of this method of obtaining fullerene-containing materials. The prototype of the invention is a classic method known from the literature for the production of cyclopropane derivative of fullerene [60] RSVM and [70] RSVM (Humelen-Woodl reaction), shown in figure 3 [J.S. Hummelen, B.W. Knight, F. LePeq, F. Wudl, J. Yao, CL Wilkins, The Journal of Organic Chemistry, 1995, 60, 532].

The specified method for producing fullerene-containing materials is possible in two versions:

1) The previous diazocompound is generated in situ in the reaction medium, and the open isomeric form [60] of PCBM is isolated. Purify by column chromatography and then undergo isomerization by boiling in 1,2-dichlorobenzene. The yield of the target product reaches 33-35%. The use of an inert atmosphere, the formation of by-products, the low yield of the target product, and the reaction time (at least 23 hours) are the main disadvantages of this embodiment of the classical Humelen-Woodl reaction.

2) The preceding diazocompound is obtained and isolated separately. Note that in this case, the yield of the target diazocompound is extremely low and amounts to only 10%. Then, the obtained product is reacted with C ₆₀ fullerene and a fulleroid is obtained, which, after purification by column chromatography, is subjected to thermal isomerization in 1,2-dichlorobenzene medium to obtain the target methanofullerene [60] PCBM in 48–50% yield. Despite the increase in the yield of the target cyclopropane derivative of fullerene, this performance of the classical Humelen-Woodl reaction seems unpromising due to the very small yield of the initial diazocompound. The disadvantages of the method of obtaining should also include the use of an inert atmosphere, the formation of by-products and the reaction time (at least 23-25 hours).

Thus, the use of the classical Humellen-Woodl reaction has a number of features. One is that the starting fullerene usually does not fully react and remains in a certain amount in the reaction mixture. In this case, it can be reduced (separated from the reaction products, for example, using column chromatography) and run again in the reaction, which will increase the final yield of fullerene derivatives. Another feature is that incorrectly selected reaction conditions (temperature, reaction time, component ratios) can shift the balance of the formed compounds towards polyadducts - fullerene compounds with two or more attached addenda. Further use of these polyadducts is not of interest. Therefore, it is very important to obtain a monoduct during the reaction with a maximum yield and low content of side impurities. We also note the sensitivity of the classical Hummelen-Woodl reaction to the conditions of its carrying out: inert atmosphere and dehydrated solvents. So, Kumar and others showed that the Hummelen-Woodl reaction under ambient conditions, even within 48 hours, leads to the formation of only 2% of the target product [R. Kumar, S. Naqvi, N. Gupta, S. Chand, RSC Advances, 2014, 4, 15675].

The objective of the invention is to simplify the process, reduce the consumption of expensive reagents, speed up the process while increasing the yield of the target product.

The tasks are solved using the developed method for producing cyclopropane derivatives of fullerenes, which provides relatively high yields of target products while simplifying the technical side of the process:

1) The reaction proceeds in one stage without using an inert atmosphere

2) The consumption of the initial reagent (tosyl hydrazone) is 2 times reduced

3) Significantly reduced reaction time.

As the base used potassium carbonate instead of sodium methylate (figure 4), the choice of which was due to its weak basicity, resistance to environmental influences (water vapor), low toxicity and lower cost relative to the cost of sodium methylate. The optimal ratio of unmodified fullerene and tosyl hydrazone (1 to 1) was selected in order to increase the yield of the target component, which allowed to reduce the consumption of tosyl hydrazone by 2 times compared with the prototype and increase the yield by 10-15%.

Thus, the proposed method for the synthesis of cyclopropane derivatives of fullerenes differs from the prototype:

1) the ability to conduct in aerobic conditions

2) using potassium carbonate as the base

3) reduced by 2 times the consumption of the initial tosylhydrazone

4) significantly reduced reaction time

5) increased by 10-15% yield of the target product

The results obtained allow us to speak with a high degree of confidence about the possibility of introducing the developed methods for the semi-industrial synthesis of fullerene derivatives.

The claimed methodology is illustrated, but not limited to the following examples.

Example 1

In a 3-necked flask equipped with a reflux condenser and a thermometer, 1 equiv. fullerene, 1 eq. tosyl hydrazone, 1.6 eq. potassium carbonate, pyridine and 1,2-dichlorobenzene. The reaction mixture was stirred for 1 hour at a temperature of 90 ° C. after cooling, the mixture was filtered through a layer of silica gel and refluxed for 3 hours. The resulting solution of the fullerene derivative was concentrated on a rotary evaporator and purified by column chromatography (the stationary phase was silica gel, the eluent was a mixture of petroleum ether and toluene). The yield of the target product is 45%. The purity of the obtained fullerene derivative was confirmed by HPLC (99.5%), the molecular composition by electrospray mass spectrometry (figures 5, 6). In figure 5 there is only one intense peak corresponding to the target product. The amount of impurities (assuming close extinction coefficients) does not exceed 0.5%.

The figure 6 presents the electrospray mass spectrum of the fullerene derivative [60] of PCVM, on which one intense signal can be observed with a molecular ion mass of m / z = 910 [M] ^- , corresponding to the molecular mass of [60] PCVM.

The spectral data correspond to the literature data [J.S. Hummelen, B.W. Knight, F. LePeq, F. Wudl, J. Yao, C. L. Wilkins, The Journal of Organic Chemistry, 1995, 60, 532].

Example 2

In a 3-necked flask equipped with a reflux condenser and a thermometer, 1 equiv. fullerene C ₆₀ , 2 equiv. tosyl hydrazone, 1.6 eq. potassium carbonate, pyridine and 1,2-dichlorobenzene. The reaction mixture was stirred for 1 hour at a temperature of 90 ° C. after cooling, the mixture was filtered through a layer of silica gel and refluxed for 3 hours. The resulting solution of the fullerene derivative was concentrated on a rotary evaporator and purified using column chromatography (the stationary phase was silica gel, the eluent was a mixture of petroleum ether and toluene). The yield of the target product is 13%. The yield of by-products of polyadducts was 83%.

Example 3

In a 3-proud flask equipped with a reflux condenser and a thermometer, 1 equiv. fullerene C ₆₀ , 1.5 eq. tosyl hydrazone, 1.6 eq. potassium carbonate, pyridine and 1,2-dichlorobenzene. The reaction mixture was stirred for 1 hour at a temperature of 90 ° C. after cooling, the mixture was filtered through a layer of silica gel and refluxed for 3 hours. The resulting solution of the fullerene derivative was concentrated on a rotary evaporator and purified using column chromatography (the stationary phase was silica gel, the eluent was a mixture of petroleum ether and toluene). The yield of the target product is 29%. The yield of by-products of polyadducts was 62%.

Example 4

In a 3-necked flask equipped with a reflux condenser and a thermometer, 1 equiv. fullerene C ₇₀ , 2 equiv. tosyl hydrazone, 1.6 eq. potassium carbonate, pyridine and 1,2-dichlorobenzene. The reaction mixture was stirred for 1 hour at a temperature of 120 ° C. after cooling, the mixture was filtered through a layer of silica gel and refluxed for 3 hours. The resulting solution of the fullerene derivative was concentrated on a rotary evaporator and purified using column chromatography (the stationary phase was silica gel, the eluent was a mixture of petroleum ether and toluene). The yield of the target product is 13%). The yield of by-products of polyadducts was 83%. The purity of the obtained fullerene derivative was confirmed by HPLC, the molecular composition using electrospray mass spectrometry (figures 7, 8).

In figure 7 there is one intense signal corresponding to the fullerene derivative [70] PCBM. The amount of impurities (assuming close extinction coefficients) does not exceed 0.9%. The electrospray mass spectrum of the fullerene derivative [60] of PCVM shows one intense signal at m / z = 1030, which refers to the molecular ion of the compound [M] ^- (figure 8). The spectral data correspond to published data [Wienk, M.M. et al. Angew. Chem. Int. Ed., 2003, 42, 3371].

Claims (1)

A method of producing a phenyl-C61-butanoic acid methyl ester ([60] RSVM) or a phenyl-C71-butanoic acid methyl ester ([70] RSVM), comprising reacting fullerene (C60, C70) with tosylhydrazone of benzoylbutyric acid methyl ester in the presence of a base in organic solvent at elevated temperature and with stirring, where the process is carried out in the presence of potassium carbonate, pyridine and 1,2-dichlorobenzene, with an equimolar ratio of tosyl hydrazone and fullerene, followed by cooling the mixture, filtering, boiling with about Ratnam condenser, concentrated on a rotary evaporator and purification by column chromatography.

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