CN105315987B - A kind of method and its preparation that secondary amine is detected using thiobarbituricacidα- derivative as probe molecule - Google Patents

Abstract

The invention discloses a method for detecting secondary amine compounds using thiobarbituric acid derivatives (TBAs) as ultraviolet-visible (UV-vis) spectrophotometric probe molecules and a preparation route thereof. The probe molecules of the present invention are prepared from primary amines through a set of systematic preparation routes. The probe molecules of the present invention have furan rings (or thiophene rings) for recognizing secondary amines, and the solution of individual probe molecules is yellow, and the solution changes from yellow to red with the addition of secondary amines. The molecular probe has high selectivity and sensitivity to secondary amines, the response range to secondary amines is 100‑400 μM, and the limit of detection (LOD) is 12 μM. The probe molecule can be used to prepare detection test paper to realize rapid and low-cost qualitative detection of secondary amines. This method can be widely used in the rapid and sensitive detection of on-line detection of secondary amine compounds in industrial processes, food analysis and environmental monitoring.

Description

A method for detecting secondary amines using thiobarbituric acid derivatives as probe molecules and its preparation

technical field

The invention relates to the technical field of chemical analysis and detection, in particular to the application of a probe molecule based on a furan ring opening mechanism in detecting secondary amine compounds and its preparation route.

Background technique

Secondary amine is a kind of organic amine, also known as secondary amine, the general formula is R ₂ NH, and primary amine (RNH ₂ ), tertiary amine (R ₃ N), quaternary ammonium salt (R ₄ N ⁺ X ^- ) Together they constitute the four major classes of organic amines. Secondary amines are the active groups of many natural products and bioactive molecules, and also the key active functional groups of many drugs such as tetracaine hydrochloride and adrenaline. Many foods contain secondary amines, such as pickled vegetables, sauerkraut, salted fish, bean paste, fried smoked fish, bacon, etc. Long-term consumption of foods containing high levels of secondary amines can lead to cancer. Therefore, the detection of secondary amine compounds has a wide range of applications in the fields of on-line monitoring of industrial production, food safety and environmental protection.

Traditional methods for distinguishing primary, secondary and tertiary amines include Hinsberg reaction, chemical titration (hydrometallurgy, 1997(2):67-69) and so on. Most of the reagents used in these methods are toxic and highly irritating to the human body. For example, the benzenesulfonyl chloride used in the Hingsburg reaction can irritate the eyes, skin, and mucous membranes and cause inflammation; the chemical titration method is cumbersome to operate, the reagent preparation is complicated, and the sensitivity is not high. Therefore, it is urgent to develop a simple and environmentally friendly detection method for secondary amines. The colorimetric method has the advantages of simplicity, rapidity, cheap and easy-to-obtain instruments, and low detection cost. For example, Suslick et al. can distinguish different levels of amines with the colorimetric group method (Angew Chem Int Ed, 2005, 44: 4528-4532), but cannot for quantitative analysis. In addition, the reaction of p-benzoquinone with secondary amines can be used to quantitatively detect secondary amines by UV-visible spectrophotometry, but this method needs to be measured at 70°C (Hydrometallurgy, 1997 (2): 67-69).

The invention provides a kind of thiobarbituric acid derivatives (thiobarbituric acid derivatives, TBAs) which is used for quantitative detection of secondary amine compounds by ultraviolet spectrophotometry at room temperature, and can also be made into test paper for qualitative analysis of secondary amines. Part of the probe molecule TBAs involved in the present invention can be used as electrophotographic photosensitive material (U.S.Patent 4,395,473.1983-7-26), photoconductive agent (U.S.Patent 4,389,477.1983-6-21), PIN1 regulation component (US.Patent Application 10/379,410.2003- 3-3.) and compounds that inhibit ubiquitin ligase activity (U.S. Patent 7,659,277.2010-2-9). Thiobarbituric acid derivatives used in the detection of secondary amines have not been reported. The invention provides a synthesis route of TBAs that can be used for secondary amine detection, a method for quantitatively detecting secondary amines based on ultraviolet-visible light spectrophotometry and a preparation method based on TBAs test paper.

Contents of the invention

One of the objectives of the present invention is to provide a series of probe molecules TBAs with good selectivity and high sensitivity for detecting secondary amines by ultraviolet-visible light spectrophotometry.

The second object of the present invention is to establish a method for detecting secondary amine compounds based on the ultraviolet-visible spectrophotometry of the probe molecule. The method has the characteristics of good selectivity, high sensitivity, simple operation, low equipment and operation cost, etc.

The third object of the present invention is to provide the probe molecules to prepare a test paper for rapid qualitative detection of volatile secondary amine compounds.

The fourth object of the present invention is to provide a synthesis route of a molecular probe for detecting secondary amine compounds with mild reaction conditions and low cost.

The probe molecule for detecting secondary amine compounds used in the present invention uses barbituric acid constructed by disubstituent thiourea derivatives, and after Knoevenagel reaction, furan aldehyde is linked to barbituric acid to obtain a target probe Molecular TBAs in which the furan ring recognizes secondary amines.

The technical scheme adopted in the present invention to solve the problem is a molecular probe for detecting secondary amine compounds by ultraviolet-visible light spectrophotometry, which has the following general structural formula:

Where: R ₁ and R ₂ are -PhCH ₃ , -PhCH ₂ CH ₃ , -phBr, -PhCl, -PhF, -PhOCH ₃ , -PhNH ₂ , -Ph, C _n H _2n+1 (n=1- 7) (wherein the substituents on the benzene ring are one of o-, p-, m-); X is O or S.

When R ₁ and R ₂ in formula 1 are both -Ph, the synthetic route of the representative compound of the present invention is shown in the following figure:

(1) Mix aniline, triethylamine and polar organic solvents in a flask, stir in an ice bath for 10-60 minutes, then add carbon disulfide dropwise to the mixture within 10-60 minutes, after the addition is completed, mix the mixture Stir at room temperature for 1-10h, remove the solvent by rotary evaporation, wash with dichloromethane several times, and dry to obtain dithioformate (b).

(2) Dissolve dithioformate b in a polar organic solvent, stir in an ice bath for 10-60 minutes, then slowly add p-toluenesulfonyl chloride, stir for 10-60 minutes, then stir at room temperature for 0.5 -5h, after the reaction is complete, remove the solvent by rotary evaporation, wash with water several times, filter and dry. Phenyl isothiocyanate (c) is obtained.

(3) Dissolve phenylisothiocyanate c in an organic solvent, add aniline under ice-bath condition, and stir for 30-90min. After the reaction is complete, filter, wash the filter cake several times with dichloromethane, and dry to obtain N,N-diphenylthiourea (d).

(4) Add N,N-diphenylthiourea d and an organic solvent into a round bottom flask, then add a certain amount of malonyl chloride, heat and reflux for 0.5-3h, after the reaction is complete, remove the solvent by rotary evaporation, and then use the concentration Quench the reaction with 0.1-3M hydrochloric acid. Pass through the column, dry and rotary evaporate. The barbituric acid derivative (e) is obtained.

(5) Add barbituric acid derivative e and polar organic solvent into the flask, stir evenly, add furan aldehyde and pyridine, stir at room temperature for 2-10h, filter, and separate by column chromatography to obtain the target product thiobarbita Toric Acid Derivatives (f).

The polar organic solvents described in steps (1), (2) and (5) in the above method are methanol, ethanol, tetrahydrofuran (THF), dimethylsulfoxide (DMSO) and the like.

The organic solvent described in steps (3) and (4) in the above method is dichloromethane, chloroform, ethyl acetate and the like.

The specific implementation of the probe molecules provided by the invention for detecting secondary amine compounds is as follows:

Secondary amine distinction

Probe molecules are formulated into a detection solution with a certain concentration, and the solvent is methanol or ethanol containing 1-20% (volume ratio) DMSO. Then prepare methanol solutions of different amines (such as ethylamine, cyclohexylamine, aniline, diethylamine, piperidine, benzylmethylamine, triethylamine, pyridine, etc.), take 1mL of the detection solution and add the corresponding equimolar amount In the amine solution, shake it well, and use it to distinguish the secondary amines by colorimetric method.

Quantitative detection of secondary amines

A methanol solution containing 1-20% (volume ratio) DMSO is used as a solvent, and a certain concentration of a probe molecule solution is prepared. Then prepare a certain concentration of secondary amine compounds (such as diethylamine, piperidine, benzylmethylamine, etc.) Evenly, stand in the dark for 0.5-1.0h, and collect data with a UV-visible spectrophotometer.

Qualitative testing of test strips

Make the probe molecules into a chloroform (or dichloromethane, etc.) solution with a concentration of 0.01%-1%, then cut the filter paper into uniform rectangular strips, then apply the chloroform solution evenly on the cut paper strips, and air dry stand-by. The test paper is then used for rapid qualitative detection of secondary amines.

The implementation of this molecular probe detection method is illustrated in more detail in the Examples of this specification. The invention can utilize the ultraviolet-visible spectrophotometry to rapidly and quantitatively detect the secondary amine compounds. As shown in formula 4 and formula 5 in the figure below, when the secondary amine compound is added, the furan ring is opened due to the interaction between the secondary amine compound and the furan ring, and the secondary amine is connected, and the solution changes from a yellow solution to a red solution.

Beneficial effects of the present invention:

The preparation method of the probe molecule of the present invention is simple to operate, the raw materials are easy to obtain, and the reaction conditions are mild.

The chemical property of the probe molecule of the invention is stable, and has good selectivity for secondary amine compounds.

The probe molecule of the present invention can distinguish secondary amine compounds through a colorimetric method in an organic solvent system. And the secondary amine compound can be quantitatively detected by ultraviolet-visible light absorptiometry (the maximum absorption wavelength is 546nm), the detection concentration range is 100-400 μM, and the detection limit is 12 μM.

Description of drawings

[Fig. 1] The probe molecules prepared in Example 1 are combined with ethylamine (a), cyclohexylamine (b), aniline (c), diethylamine (d), piperidine (e), benzyl methyl Color chart of the effects of amine (f), triethylamine (g), pyridine (h) and blank (i).

[ Fig. 2 ] is the ultraviolet-visible light absorption spectrum at 450nm-650nm of the molecular probe prepared in Example 1 in methanol system and different concentrations of benzylmethylamine.

[ Fig. 3 ] is a graph showing the linear relationship between the absorbance of the probe molecule prepared in Example 1 and the concentration of benzylmethylamine at 546 nm.

[ Fig. 4 ] is the ultraviolet-visible light absorption spectrum at 450nm-650nm of the probe molecule prepared in Example 1 and different concentrations of piperidine.

[ Fig. 5 ] is a graph showing the linear relationship between the absorbance at 546 nm and the piperidine concentration of the probe molecule prepared in Example 1.

[ Fig. 6 ] is the proton nuclear magnetic resonance spectrum of the probe molecule prepared in Example 1.

[Fig. 7] is the probe molecule that embodiment 3 makes respectively with ethylamine (a), cyclohexylamine (b), aniline (c), diethylamine (d), piperidine (e), benzyl methyl Color chart of the effects of amine (f), triethylamine (g), pyridine (h) and blank (i).

[ Fig. 8 ] is the ultraviolet-visible light absorption spectrum at 475nm-645nm of the probe molecule prepared in Example 3 and different concentrations of diethylamine.

[ Fig. 9 ] is a graph showing the linear relationship between the absorbance at 546 nm and the concentration of diethylamine of the probe molecule prepared in Example 3.

[ Fig. 10 ] is the proton nuclear magnetic resonance spectrum of the probe molecule prepared in Example 3.

[Fig. 11] It is the experimental diagram of the interaction between the test paper made of molecules obtained in Example 3 and different volatile amine gases, from left to right blank (a), ethylamine (b), diethylamine (c), three Ethylamine (d), piperidine (c), pyridine (f).

detailed description

The following examples are intended to further illustrate the content of the present invention. Rather than limiting the protection scope of the present invention.

Embodiment 1: Preparation of probe molecule 1,3-diphenyl 5 (2-furyl methylene) thiobarbituric acid (DPFTBA)

Aniline (11mmol), triethylamine (36.2mmol) and tetrahydrofuran 10mL were placed in a flask, stirred in an ice bath for 10min, and then carbon disulfide (11mmol) was added dropwise to the mixture within 30min; The solution was stirred and reacted at room temperature for 10 h; then cooled in an ice bath, TsCl (12.1 mmol) was slowly added, and stirred for 1 h to obtain 0.965 g of phenyl isothiocyanate. Dissolve 0.965g of phenyl isothiocyanate in dichloromethane, add 0.665g of aniline under ice-cooling condition, and stir for 45min. After the reaction is complete, filter; wash the filter cake several times with dichloromethane, and dry to obtain 1.497 g of N,N-diphenylthiourea. Mix 1.497g of N,N-diphenylthiourea and dichloromethane in a round bottom flask, then add 7mmol of malonyl chloride, heat to reflux for 1h, after the reaction is complete, remove the solvent by rotary evaporation, and then add 1mL of 1.0M hydrochloric acid to quench the reaction. Wash, dry, and separate by column chromatography to obtain barbituric acid derivatives. Mix barbituric acid derivatives and ethanol in a flask, stir well, add excess furan aldehyde and 0.5mL pyridine, stir at room temperature for 2-3h, filter, and separate by column chromatography to obtain the target product

1,3-Diphenyl 5(2-furylmethylene)thiobarbituric acid (1,3-diphenyl-5-(2-furan-methylene)thiobarbituric acid) (structure shown in formula 4) 0.346g.

¹ HNMR (400MHz, CDCl ₃ ): δppm=8.74(d, J=3.9Hz, 1H), 8.58(s, 1H), 7.93(d, J=1.2Hz, 1H), 7.62-7.44(m, 6H) , 7.32 (ddd, J = 13.7, 7.9, 3.3 Hz, 4H), 6.78-6.70 (m, 1H). (See Figure 6 for NMR image)

Embodiment 2: Preparation of probe molecule 1,3-diethyl-5-(2-furyl methylene) thiobarbituric acid (DEFTBA)

Using steps similar to Example 1, 1,3-diethyl-2-thiobarbituric acid was obtained, which was mixed with ethanol and stirred evenly, and excess furan aldehyde and 0.5 mL pyridine were added, and stirred at room temperature for 2-3 h, Filtration, column chromatography separation, obtain target product 1,3-diethyl-5-(2-furyl methylene) thiobarbituric acid (1,3-diethyl-5-(2-furan-methylene )thiobarbituric acid) (structure shown in formula 6) 0.56g.

¹ HNMR (400MHz, CDCl ₃ ): δppm=8.73(d, J=3.9Hz, 1H), 8.46(s, 1H), 7.91(d, J=1.2Hz, 1H), 6.78(ddd, J=3.8, 1.5, 0.7Hz, 1H), 4.59 (qd, J = 7.0, 4.6Hz, 4H), 1.33 (q, J = 6.9Hz, 6H). (See Figure 10 for NMR image)

Embodiment 3: the application of the probe that detects secondary amines

The molecular probe (abbreviation) in Example 1 was dissolved in a mixed solvent of methanol containing 2% DMSO to prepare a probe solution with a concentration of 0.1 mg/mL. Add it into different solutions to be tested, shake it well at room temperature, let it stand in the dark for 0.5-1.0 h, and collect data with an ultraviolet-visible spectrophotometer.

Figure 1 shows the selectivity of its secondary amine compounds in the colorimetric physical map.

Figures 2 to 5 show the spectral properties of the probe molecules, the relationship between the concentration of the secondary amine and the absorbance, etc.

Embodiment 4: the application of the probe that detects secondary amines

The probe molecule (abbreviated) synthesized in Example 2 was dissolved in a mixed solvent of methanol containing 2% DMSO to prepare a 0.25 mg/mL probe solution for use. Then add to the detection solution containing amines.

Figure 1 shows the selectivity of its secondary amine compounds in the colorimetric physical map.

Figures 2 to 5 show the spectral properties of the probe molecules, the relationship between the concentration of the secondary amine (diethylamine) and the absorbance, etc.

The probe molecule was made into a 1 mg/mL chloroform solution, and the solution was spread on a strip of filter paper, and then air-dried for qualitative detection of secondary amines.

Figure 11 demonstrates the selectivity of probe molecules to volatile secondary amines.

Claims (4)

1. A method for detecting secondary amines is characterized in that, utilizing thiobarbituric acid derivatives as probe molecules, secondary amines are qualitatively and/or quantitatively detected, and its probe molecular structure is as shown in formula 1: Wherein R ₁ and R ₂ are any one of -PhCH ₃ , -PhCH2CH ₃ , -PhBr, -PhCl, -PhF, -PhOCH ₃ , -PhNH ₂ , -Ph, C _n H _2n+1 , respectively, wherein benzene The substituents on the ring are one of o-, p-, m-; R ₁ and R ₂ can be different substituents, and n=1-7; X is O or S. 2. The method for detecting secondary amines according to claim 1, characterized in that, when using the colorimetric method, the molecular probe is dissolved in a mixed solution of methanol or ethanol and dimethyl sulfoxide to test the secondary amines. 3. the method for detecting secondary amine according to claim 1, is characterized in that, utilizes formula 1 structural probe molecule to be applied to ultraviolet-visible light spectrophotometry secondary amine compound is carried out quantitative detection, and described spectrophotometry is to secondary amine compound. The detection concentration range of amine compounds is 100-400 μM, and the detection limit is 12 μM. 4. The method for detecting secondary amines according to claim 1, characterized in that, it is prepared into a test paper and applied to the rapid qualitative detection of volatile secondary amine compounds.