Month: June 2021

Researchers who often do experiments know that organic synthesis is a process of preparing more complex target molecules from simple raw materials through one or more chemical reactions. Generally, it requires fewer steps, and cheap raw materials. 5521-55-1, name is 5-Methylpyrazine-2-carboxylic acid, A new synthetic method of this compound is introduced below., Formula: C6H6N2O2

tert-Butyl (5-methylpyrazin-2-yl)carbamate To a flask fitted with overhead stirrer, condenser, thermometer and nitrogen line was added 5-methylpyrazine-2-carboxylic acid (1.0 eq), tert-butanol (3.5 vols) and di-isopropylethylamine (1.5 eq) under a nitrogen atmosphere. The mixture was heated to 82 C., then diphenylphosphorylazide (1.0 eq) was added over a time period of 5-14 hours, maintaining the temperature of the reaction mixture at approximately 82 C. The reaction mixture was stirred for at least 1.5 hours, and then cooled to approximately 60 C. A solution of 4% w/w sodium hydroxide (1.75 eq) was added over a period of 2 hours. The mixture was cooled to 15 C. over at least 5 hours then held at 15 C. for 3 hours. The batch was then filtered, and the solid slurry washed with water (2 vols). The batch was again slurry washed with water (2 vols). After drying at 55-60 C. overnight, the desired product was obtained as a solid (corrected yield 56-63%). 1H NMR delta (400 MHz CDCl3): 9.18 (s, 1H), 8.17 (bs, 1H), 8.11 (s, 1H), 2.51 (s, 3H), 1.56 (s, 9H)

The synthetic route of 5521-55-1 has been constantly updated, and we look forward to future research findings.

Reference:
Patent; AstraZeneca AB; US2010/210621; (2010); A1;,
Pyrazine – Wikipedia,
Pyrazine | C4H4N2 – PubChem

Reference of 3149-28-8, In the chemical reaction process, reaction time, type of solvent, can easily affect the result of the reaction, thereby determining the yield and properties of the reaction product. An updated downstream synthesis route of 3149-28-8 as follows.

Alternate synthesis of (8) A solution of 5.4 ml of 2,2,6,6-tetramethylpiperidine, in 300 ml of dry THF was cooled to -8C as 19 ml of 1.6 M butyllithium (0.03 mol) in hexane was added dropwise. The reaction was stirred 20 min then cooled to -77C. A solution of 2.5 g of 2-methoxypyrazine (0.023 mol) in 5 ml of THF was added dropwise to the reaction. After 5h, 2.9 g of 3-quinuclidinone (0.023 mol) in 5 ml of THF was added dropwise and the reaction stirred another h. A solution of 8 ml of concentrated HCl and 4 ml of ethanol was added, the cooling was removed, and when the temperature reached -10C, 20 ml of 5 N NaOH was added. The volatile organics were evaporated and the residue extracted 3X with 50 ml of CHCl3 The extracts were washed with brine, dried, and the solvent evaporated to give a clear yellow liquid that solidified on further drying. Recrystallization from ether gave 3.53 g of (8) identical to the material produced in the previous reaction.

According to the analysis of related databases, 3149-28-8, the application of this compound in the production field has become more and more popular.

Reference:
Patent; NOVO NORDISK A/S; EP521067; (1995); B1;,
Pyrazine – Wikipedia,
Pyrazine | C4H4N2 – PubChem

Electric Literature of 6863-73-6,Some common heterocyclic compound, 6863-73-6, name is 3-Chloropyrazin-2-amine, molecular formula is C4H4ClN3, traditional synthetic route has been very mature, but the traditional synthetic route has various shortcomings, such as complicated route, low yield, poor purity, etc, below Introduce a new synthetic route.

EXAMPLE 1 3-Chloro-2-nitropyrazine STR11 Step A: S,S-Dimethyl-N-(3-chloropyrazin-2-yl)sulfilimine (2) To a mechanically stirred solution of 3.9 g (0.05 mol) dimethyl sulfoxide in 30 ml dry methylene chloride at -78 under nitrogen is added 13.1 g (0.046 mol) trifluoromethanesulfonic anhydride dropwise to afford a white precipitate. To this is added a solution of 5.0 g (0.039 mol) 2-amino-3-chloropyrazine (1) in 30 ml methylene chloride/15 ml dimethyl sulfoxide and the resulting solution is stirred at -78 for 2 hours and at -55 for 1 hour. The reaction mixture is then quenched with 50 ml of 5% aqueous sodium bicarbonate solution and stirred at -5 for 5 minutes. The reaction mixture is diluted with 200 ml methylene chloride and the phases are separated. The aqueous phase is extracted with 250 ml methylene chloride and the combined organic phases are washed with 3*75 ml portions of water and dried over anhydrous sodium sulfate. The solvent is removed from the rotary evaporator to give 5.8 g (79%) of 2 as yellow crystals, m.p. 106-108.

These compound has a wide range of applications. It is believed that with the continuous development of the source of the synthetic route 3-Chloropyrazin-2-amine, its application will become more common.

Reference:
Patent; Merck & Co., Inc.; US4709035; (1987); A;,
Pyrazine – Wikipedia,
Pyrazine | C4H4N2 – PubChem

Synthetic Route of 186534-02-1, In the next few decades, the world population will flourish. As the population grows rapidly and people all over the world use more and more resources, all industries must consider their environmental impact. 186534-02-1, name is 3,5,6-Trimethylpyrazine-2-carbaldehyde belongs to pyrazines compound, it is a common compound, a new synthetic route is introduced below.

A cyclopentanone was added sequentially to a 25O mL three-necked flask(1 OmL, 0.115mo 1),Morpholine (1 OmL, 0.114 mol), benzene 100 mL,Reflux reaction to the oil-water separator after the formation of anhydrous,The reaction solution was cooled to room temperature,Add p-methoxybenzaldehyde(13 mL, 0.115 mol), refluxed for 8 h,TLC (petroleum ether – ethyl acetate = 1: 1) detection reaction is basically complete,Slowly add 6mol / L HC1 50mL,Stirring at room temperature lh,Then add 10% NaHC03 solution 115mL,Stirring at room temperature for 30min,The solution was poured into a separatory funnel,The layers were allowed to stand, the organic layer was dried over anhydrous sodium sulfate,concentrate. Dissolved in 40 mL of absolute ethanol,Add 1.5g of Chuanxiong aldehyde (0.0lmo 1),Ice bath conditions slowly add 10% NaOH ethanol solution 5mL,Reaction about lh,TLC (petroleum ether – ethyl acetate = 2: 1) detection reaction is basically complete,The precipitate was filtered off and the precipitate was washed with absolute ethanol,Purification by silica gel column chromatography (dichloromethane: ethyl acetate = 2: 1) gave 2.01 of Z1 yellow crystals,The yield was 6 1.2%.

In the field of chemistry, the synthetic routes of compounds are constantly being developed and updated. I will also mention this compound in other articles, 3,5,6-Trimethylpyrazine-2-carbaldehyde, other downstream synthetic routes, hurry up and to see.

Reference:
Patent; Anhui University of Chinese Medicine; Hefei Medical Engineering Pharmaceutical Co., Ltd.; Hefei Enruite Pharmaceutical Co., Ltd.; Li Jiaming; He Guangwei; Zhang Yang; Huang Weijun; Zhang Yanchun; Liu Weizhong; Zuo Jian; Liu Huicai; Zhu Panhu; Wang Yujun; (14 pag.)CN106518791; (2017); A;,
Pyrazine – Wikipedia,
Pyrazine | C4H4N2 – PubChem

Electric Literature of 68774-77-6, In the next few decades, the world population will flourish. As the population grows rapidly and people all over the world use more and more resources, all industries must consider their environmental impact. 68774-77-6, name is 8-Chloro[1,2,4]triazolo[4,3-a]pyrazine belongs to pyrazines compound, it is a common compound, a new synthetic route is introduced below.

EXAMPLE 1.28. (3 ?,4S)-4-methylbenzyl 4-(([l,2,4]triazolo[4,3-a]pyrazin-8-ylamino)methyl)-3- fluoropiperidine-l-carboxylate (E2-1.2). [0265] A mixture of 8-chloro-[l,2,4]triazolo[4,3-a]pyrazine (120 mg, 0.78 mmol), (3R,4S)-4- methylbenzyl 4-(aminomethyl)-3-fluoropiperidine-l-carboxylate hydrochloride (297 mg, 0.94 mmol) and DIPEA (0.65 mL, 3.9 mmol) in n-BuOH (4 mL) was heated to 120C under N2 atmosphere. After stirring overnight at 120C, the mixture was cooled down to room temperature and concentrated under vacuum. The concentrate was partitioned into EtOAc and water. The organic phase was washed with water, brine, dried over Na2S04 and concentrated. The concentrate was purified by column chromatography over silica gel (eluent: 100% ethyl acetate) to afford the title compound as a brown powder (187 mg, 78%). MS (ESI) calcd for C20H23FN6O2: 398.2; found: 399.3[M+H]. *H NMR (400 MHz, CD3OD) delta 9.09 (s, 1H), 7.69 (d, J = 4.8 Hz, 1H), 7.30 (d, J = 4.8 Hz, 1H), 7.24 (d, J = 8.0 Hz, 2H), 7.16 (d, J = 8.0 Hz, 2H), 5.08 (s, 2H), 4.85-4.71 (m, 1H), 4.50-4.40 (m, 1H), 4.28-4.20 (m, 1H), 3.68-3.63 (m, 1H), 3.60-3.55 (m, 1H), 3.11-3.00 (m, 1H), 2.95-2.80 (m, 1H), 2.33 (s, 3H), 2.30-2.11 (m, 1H), 1.71-1.57 (m, 2H).

In the field of chemistry, the synthetic routes of compounds are constantly being developed and updated. I will also mention this compound in other articles, 8-Chloro[1,2,4]triazolo[4,3-a]pyrazine, other downstream synthetic routes, hurry up and to see.

Reference:
Patent; RUGEN HOLDINGS (CAYMAN) LIMITED; SHAPIRO, Gideon; (239 pag.)WO2016/100349; (2016); A2;,
Pyrazine – Wikipedia,
Pyrazine | C4H4N2 – PubChem

Researchers who often do experiments know that organic synthesis is a process of preparing more complex target molecules from simple raw materials through one or more chemical reactions. Generally, it requires fewer steps, and cheap raw materials. 33332-28-4, name is 2-Amino-6-chloropyrazine, A new synthetic method of this compound is introduced below., Recommanded Product: 33332-28-4

Pre Step A 6-(Methyloxy)-2-pyrazinamine A mixture of 6-chloro-2-pyrazinamine (200 mg, 1.544 mmol) and sodium methoxide (250 mg, 4.63 mmol) in methanol (3.9 ml) was heated to 130° C. via a microwave reactor for 60 min. The crude product mixture was purified by RP-HPLC to give 6-(methyloxy)-2-pyrazinamine (154 mg, 1.231 mmol, 80percent yield). MS (ES+) m/z 125.8 (MH+).

The basis of chemical reaction formula synthesis, the synthesis route is composed of some specific reactions and combined according to certain logical thinking. We look forward to the emergence of more reaction modes in the future.

Reference:
Patent; Glaxosmithkline LLC; Aubart, Kelly M.; Benowitz, Andrew B.; Fang, Yuhong; Hoffman, James; Karpinski, Joseph M.; Knox, Andrew Nicholson; Liao, Xiangmin; Qin, Donghui; Shi, Dongchuan; Spletstoser, Jared T.; US2013/345120; (2013); A1;; ; Patent; GlaxoSmithKline Intellectual Property (No. 2) Limited; Aubart, Kelly M.; Benowitz, Andrew B.; Fang, Yuhong; Hoffman, James; Karpinski, Joseph M.; Knox, Andrew Nicholson; Liao, Xiangmin; Qin, Donghui; Shi, Dongchuan; Spletstoser, Jared T.; US8901119; (2014); B2;,
Pyrazine – Wikipedia,
Pyrazine | C4H4N2 – PubChem

These common heterocyclic compound, 1379338-74-5, name is 5,7-Dichloropyrido[3,4-b]pyrazine, its traditional synthetic route has been very mature, but the traditional synthetic route has various shortcomings, such as complicated route, low yield, poor purity, etc, below Introduce a new synthetic route. Computed Properties of C7H3Cl2N3

Intermediate 37: 1 ,1 -dimethylethyl 3-{r(7-chloropyridor3,4-fllpyrazin-5- yl)amino1methyl)-4,4-difluoro-1 -piperidinecarboxylate (Isomer 2); 5,7-Dichloropyrido[3,4-b]pyrazine (620mg, 3.10mmol) was dissolved in N-methyl-2- pyrrolidinone (NMP) (5mL) and to this was added DIPEA (0.601 ml_, 4.65mmol) and 1 , 1-dimethylethyl 3-(aminomethyl)-4,4-difluoro-1-piperidinecarboxylate (776mg, 3.10mmol). This was heated in a microwave at 130C for 30min. The reaction mixture was partitioned between ethyl acetate and water. The aqueous was re-extracted twice with ethyl acetate and the combined organic layers washed with brine, dried over a hydrophobic frit and concentrated in vacuo to yield a brown oil. It was dissolved in DCM and passed through silica (100g) eluting with a 10-50% ethyl acetate in cyclohexane gradient. Appropriate fractions were combined and concentrated in vacuo to yield the title compound as a yellow solid, 1.0g.Chiral separation was achieved (Sample preparation: Sample dissolved in ethanol (30ml) sonicating and heating with air gun as required. 4-5ml injections were then pumped onto a preparative scale Whelk-0 (S, S) column (2 inch). Details as follows: Column – Whelk-0 (S, S) (50x250mm, l Omicron); Detection – UV DAD – 300nm (bandwidth 180nm, reference 550nm (bandwidth 100nm)); Flow Rate – 70ml/min; Mobile Phase A: Heptane; Mobile Phase B: I PA; Isocratic method (premixed) 5% B; Runtime – 60min; Number of runs – 8) to yield the title compound (second eluting peak from the chiral column) as a yellow solid (441 mg).LCMS (Method B): Rt =1.27min, MH+ =414 The following intermediate was obtained as the first eluting peak from the chiral separation above:; Intermediate 38: 1 ,1 -dimethylethyl 3-{r(7-chloropyridor3,4-fllpyrazin-5- yl)amino1methyl)-4,4-difluoro-1 -pipendinecarboxylate (Isomer 1); LCMS (Method B): Rt =1.27min, MH+ =414The following intermediate was prepared similarly:Intermediate 39: 1 ,1 -dimethylethyl 5-{r(7-chloropyridor3,4-fllpyrazin-5-LCMS (Method B): Rt =1.24min, MH+= 414

The synthetic route of 5,7-Dichloropyrido[3,4-b]pyrazine has been constantly updated, and we look forward to future research findings.

Reference:
Patent; GLAXO GROUP LIMITED; ATKINSON, Francis Louis; ATKINSON, Stephen John; BARKER, Michael David; DOUAULT, Clement; GARTON, Neil Stuart; LIDDLE, John; PATEL, Vipulkumar Kantibhai; PRESTON, Alexander G; SHIPLEY, Tracy Jane; WILSON, David Matthew; WATSON, Robert J; WO2012/123312; (2012); A1;,
Pyrazine – Wikipedia,
Pyrazine | C4H4N2 – PubChem

Reference of 13924-94-2, The chemical industry reduces the impact on the environment during synthesis 13924-94-2, name is Methyl 5-aminopyrazine-2-carboxylate, I believe this compound will play a more active role in future production and life.

To a solution of Int-1 (100 g, 1.063 mmol)) in DME (400 mL) was added Int-2 (155 g, 1.595 mmol) at room temperature. The reaction mixture was heated to 85 C. and stirring was continued overnight. The volatiles were concentrated under reduced pressure, then residue was diluted with water (500 mL) and dichloromethane (500 mL). The pH was adjusted to neutral by using sat. NaHCO3. The organic layer was separated, dried over anhydrous Na2SO4 and concentrated under reduced pressure. The residue was purified through silica gel column chromatography, eluted with ethyl acetate to afford Int-3 (40 g, 28.5%) as syrup. To a solution of Int-3 (40 g, 0.303 mol) in acetonitrile (200 mL) was added N-Iodo succinamide (81 g, 0.3636 mol) at room temperature, and then stirred for 1 hour. The reaction mixture was poured into water and stirred for 30 minutes. The precipitated solids were filtered and solids were triturated in ethyl acetate (1 L), filtered solid, and washed with ethyl acetate. Then filtrate was washed with 10% Na2CO3 solution (250 mL), water, dried over anhydrous Na2SO4 and concentrated under reduced pressure to afford Int-4 (18.1 g, 23%) as a solid. Mass (m/z): 259 [M++1]. 1H NMR (200 MHz, dmso-d6): delta 8.43 (d, J=8 Hz, 1H), 7.69-7.53 (m, 2H), 7.23 (t, J=6.6 Hz, 1H), 2.42 (s, 3H). To a suspended solution of Int-5 (12 g, 46.51 mmol) in IPA: water (80 mL: 30 mL) was added Pd Cl2(dppf).DCM (7.5 g, 9.3 mmol), tertiary butyl amine (4.9 g, 69.76 mmol) and Na2CO3 (7.3 g, 69.76 mmol) at room temperature. The reaction mixture was heated to 100 C. and stirring was continued overnight. The reaction mixture was allowed to room temperature, and then diluted with dichloromethane (250 mL) and water. The organic layer was separated, washed with 10% Na2CO3 solution (75 mL), dried over anhydrous Na2SO4 and concentrated under reduced pressure. The residue was purified through silica gel column chromatography, eluted product with ethyl acetate to afford Int-6 (4.8 g, 42.4%) as a solid. Mass (m/z): 244 [M++1]. 1H NMR (200 MHz, dmso-d6): delta 8.51 (t, J=5 Hz, 2H), 7.71 (s, 1H0, 7.63-7.55 (m, 2H), 7.34 (t, J=7 Hz, 1H), 6.94 (t, J=7 Hz, 1H), 2.43 (s, 3H). To a solution of Int-7 (1 g, 5.797 mmol) in THF (10 mL) was added 4-methoxy benzyl amine (1.98 g, 14.49 mmol) at room temperature and, then stirred overnight. The reaction mixture was filtered, concentrated under reduced pressure. The residue was purified through silica gel column chromatography, eluted product with 50% ethyl acetate/dichloromethane to afford Int-8 (800 mg, 50.6%) as a solid. Mass (m/z): 274 [M++1]. 1H NMR (200 MHz, dmso-d6): delta 8.6 (s, 1H), 8.61-8.42 (brs, 1H), 8.01 (s, 1H), 7.23 (d, J=8.5 Hz, 2H), 6.83 (d, J=8.4 Hz, 2H). To a solution of Int-8 (800 mg, 2.925 mmol) in trifluoro acetic acid (5 mL) was stirred for 1 hour at 60 C. The reaction mixture was allowed to room temperature, and then quenched with solid sodium bicarbonate. The reaction mixture was diluted with ethyl acetate and water. The organic layer was separated, dried over anhydrous Na2SO4 and concentrated under reduced pressure rotavapour to afford Int-9 (350 mg, 78%) as a solid. Mass (m/z): 154 [M++1]. 1H NMR (200 MHz, dmso-d6): delta 8.51 (s, 1H), 8.7.83 (s, 1H), 7.39 (brs, 2H), 3.79 (s, 3H). To a solution of Int-6 (1.58 g, 6.535 mmol) in 1,4-dioxane (25 mL) was added palladium acetate (238 mg, 1.045 mmol), Xantpos (498 mg, 1.045 mmol), Int-9 (1 g, 6.535 mmol) and cesium carbonate (3.21 g, 9.802 mmol) at room temperature. The reaction mixture was heated to 100 C. and stirring was continued for 18 hours. The reaction mixture was concentrated under reduced pressure, then residue was diluted with ethyl acetate. The precipitated solids were filtered, then washed with water (25 mL) and dried under vacuum. The solids were purified through silica gel column chromatography, eluted product with 3% methanol/dichloromethane to afford Int-10 (200 mg, 8.5%) as a solid. Mass (m/z): 361 [M++1]. 1H NMR (200 MHz, dmso-d6): delta 10.8 (brs, 1H), 9.06 (s, 1H), 8.09 (s, 1H), 8.59-8.4 (m, 2H), 8.01 (s, 1H), 7.6 (d, J=7.4 Hz, 1H), 7.7.29-7.2 (m, 2H), 6.98 (t, J=7 Hz, 1H), 3.81 (s, 3H). To a solution of Int-10 (200 mg, 0.555 mmol) in methanol (4 mL) and dichloromethane (10 mL) was added hydroxyl amine solution (aqueous 50%) (4 mL) and reaction mixture was stirred for 20 minutes at 0 C. Then sodium hydroxide solution (3 mL) was added and the reaction mixture was allowed to room temperature, then stirred for 5 hours. The volatiles were concentrated under reduced pressure, then adjusted pH to neutral by using 1N HCl at 0 C. The precipitated solids were filtered, washed with water, dichloromethane and hexanes to afford the title compound (150 mg, 75%) as a solid. Mass (m/z): 362 [M++1]. (1H NMR 200 MHz (dmso-d6): delta 10.96 (brs, 1H), 9.01 (s, 1H), 8.72 (s, 1H), 8.54 (d, J=6.6 Hz, 1H), 8.47 (d, J=5.4 Hz, 1H), 7.99 (s, 1H), 7.6 (d, J=8.8 Hz, 1H), 7.33 (t, J=7.6 Hz, 1H), 7.24 (d, J=3.8 Hz, 1H), 6.99 (t, J=7 Hz, 1H), 6.42 (s,…

In the field of chemistry, the synthetic routes of compounds are constantly being developed and updated. I will also mention this compound in other articles, Methyl 5-aminopyrazine-2-carboxylate, other downstream synthetic routes, hurry up and to see.

Reference:
Patent; Melvin, JR., Lawrence S.; Graupe, Michael; Venkataramani, Chandrasekar; US2010/29638; (2010); A1;,
Pyrazine – Wikipedia,
Pyrazine | C4H4N2 – PubChem

These common heterocyclic compound, 75907-74-3, name is (3,5,6-Trimethylpyrazin-2-yl)methanol, its traditional synthetic route has been very mature, but the traditional synthetic route has various shortcomings, such as complicated route, low yield, poor purity, etc, below Introduce a new synthetic route. Computed Properties of C8H12N2O

The obtained 7.5 g of TMP-OH (49.3 mmol) was dissolved in 50 ml of absolute ethanol to add active manganese dioxide.(6.4g, 73.6mmol) was oxidized and reacted in an oil bath at 84 C for 2 h. After the TLC reaction was completed,The reaction solution was carefully filtered with a five-layer filter paper while hot, and the manganese dioxide powder was removed.After filtration, a clear filtrate was obtained, which was evaporated to dryness under reduced pressure on a rotary evaporator. Wet loading column chromatography:The mobile phase EA:PE (1:5) was separated and purified, and the fraction was monitored by TLC. Collecting the compound 1a-4 fraction,Combine the same fraction and distill it to obtain a crystalline white solid.5.5g (36.7mmol),[M+H]+=151 is 1a-4 (TMP-CHO), yield 75%.

The synthetic route of (3,5,6-Trimethylpyrazin-2-yl)methanol has been constantly updated, and we look forward to future research findings.

Reference:
Patent; Guangzhou Xique Pharmaceutical Co., Ltd.; Wang Yuqiang; Yao Hui; Wu Chuanbin; Tao Liang; Sun Yewei; (27 pag.)CN103804309; (2019); B;,
Pyrazine – Wikipedia,
Pyrazine | C4H4N2 – PubChem

In the next few decades, the world population will flourish. As the population grows rapidly and people all over the world use more and more resources, all industries must consider their environmental impact. 22047-25-2, name is Acetylpyrazine belongs to pyrazines compound, it is a common compound, a new synthetic route is introduced below. SDS of cas: 22047-25-2

General procedure: To a stirred solution of aldehyde (10mmol) (4-(dimethylamino)benzaldehyde, 4-(1-piperidinyl)benzaldehyde, 4-(4-morpholinyl)benzaldehyde or 4-(diphenylamino)benz-aldehyde) in EtOH (75mL), ketone (20mmol) (2-acetylpyridine, 2-acetylthiazole or 2-acetylpyrazine) was added. Then KOH (1.54g, 27.5mmol) and NH3 (aq) (35mL) were added to the reaction mixture. The solution was stirred at room temperature for 24h. The solid was collected by filtration and washed with H2O. Recrystallization from ethanol (1, 4, 7, 10) or toluene (2, 3, 5, 6, 8, 9, 11, 12) afforded a crystalline solid.

The synthetic route of 22047-25-2 has been constantly updated, and we look forward to future research findings.

Reference:
Article; Palion-Gazda, Joanna; Machura, Barbara; Klemens, Tomasz; Szlapa-Kula, Agata; Krompiec, Stanis?aw; Siwy, Mariola; Janeczek, Henryk; Schab-Balcerzak, Ewa; Grzelak, Justyna; Ma?kowski, Sebastian; Dyes and Pigments; vol. 166; (2019); p. 283 – 300;,
Pyrazine – Wikipedia,
Pyrazine | C4H4N2 – PubChem