The reaction of an aromatic heterocycle with a proton is called a protonation. One of articles about this theory is 《Purines, pyrimidines, and glyoxalines. VII. New syntheses of 2-thiouracils and 2-thiothymines》. Authors are Shaw, G.; Warrener, R. N..The article about the compound:Ethyl 3-Ethoxy-2-Propenoatecas:1001-26-9,SMILESS:O=C(OCC)/C=C/OCC).Synthetic Route of C7H12O3. Through the article, more information about this compound (cas:1001-26-9) is conveyed.
cf. C.A. 51, 17939f. β-Ethoxy-acryloyl (I) and β-methoxy-α-methylacryloyl isothiocyanate (II) were prepared by reaction of the corresponding acid chlorides (III) (IV) with KSCN. I and II with NH3 or primary amines gave linear acylthioureas which when treated with dilute aqueous alkali afforded 1-substituted 2-thiouracils and 2-thiothymines. Reaction of the acyl isothiocyanates with PhNHNH2 (V) similarly gave acylthiosemicarbazides which with alkali afforded thiotriazoles. BrCH2CO2Et (334 g.), 400 mg. CH(OEt)3, and 1 kg. Zn shavings gave 104 g. Et β-ethoxyacrylate (VI), b. 189-91°. VI (48 g.) stirred 2 hrs. on an H2O bath with 180 ml. 2N NaOH, cooled, and acidified gave 35 g. β-ethoxyacrylic acid (VII), m. 109°. Na salt of VII (15 g.) refluxed 4 hrs. in 200 ml. Et2O containing 10 ml. SOCl2, kept overnight, and filtered through asbestos gave 11.5 g. III, b35104°. III (9.33 g.) in 50 ml. dry MeCN shaken 3 hrs. with 6.8 g. KSCN gave 6.2 g. I, b1.5 90°. I (1.35 g.) reacted vigorously with 3 ml. 3.34N MeOH-NH3 to give 0.74 g. N-(β-ethoxyacryloyl)thiourea (VIII), prisms, m. 165° (alc.). VIII (0.5 g.) heated 45 min. with 5 ml. 2N NaOH, cooled, acidified, and the solids triturated with a little alc. gave 0.05 g. 2-thiouracil, needles, m. 304° (decomposition). I (0.84 g.) in 15 ml. Et2O treated with 0.5 ml. 33% MeOH-MeNH2 gave 0.45 g. N-(β-ethoxyacryloyl)-N’-methylthiourea (IX), needles, m. 124° (alc.). IX (0.35 g.) warmed with 4 ml. 2N NaOH gave 0.23 g. 1-methyl-2-thiouracil, m. 228° (alc.). Similarly, 1.15 g. I and 0.7 g. PhNH2 mixed in Et2O gave 1.25 g. N-(β-ethoxyacryloyl)-N’-phenylthiourea (X), plates, m. 152°. X (0.85 g.) similarly heated 15 min. with alkali gave 0.68 g. 1-phenyl-2-thiouracil, laths, m. 236° (alc.). I (0.87 g.), 0.6 g. V, and 5 ml. alc. gave 0.87 g. N1-(β-ethoxyacryloyl)-N3-phenylthiosemicarbazide (XI), plates, m. 161° (alc.). XI (0.4 g.) heated 5 min. with 5 ml. 2N NaOH and the cooled solution acidified gave 0.37 g. 5-β-ethoxyvinyl-2,3-dihydro-1-phenyl-3-thio-1,2,4-triazole, prisms, m. 161°. The following method was found suitable for the preparation of β-methoxy-α-methylacrylic acid (XII). Me α,β-dibromo-α-methylpropionate (467 g.) in 500 ml. MeOH refluxed with 82.6 g. Na in 1 l. MeOH, next morning the mixture filtered, the filtrate and washings evaporated to half volume, NaBr again removed, most of the solvent removed, the residue treated with 250 ml. H2O, the precipitated oil extracted with Et2O, and the residue from the Et2O evaporation heated with 1.5 g. fused NaHSO4 at 170° until the evolution of alc. was complete, and the residue distilled gave 159 g. Me β-methoxy-α-methylacrylate (XIII), b10 66-7°, n23D 1.455. XIII (39 g.) heated with alkali 3 hrs. gave 35.5 g. XII, plates, m. 106° (ligroine). XII Na salt was prepared by neutralizing a suspension of XII in H2O with 2N NaOH, evaporating to dryness, and drying the salt at 100°/0.5 mm. for 4.5 hrs. before using. This salt (25.72 g.) suspended in 100 ml. Et2O treated with 16 ml. SOCl2 in 100 ml. Et2O and finally refluxed 3 hrs. gave 20 g. IV, b35 102°. IV with a little H2O gave XII. IV (8.6 g.) in 50 ml. MeCN treated with 6.2 g. KSCN gave 7.2 g. II, b2 102°, plates, melting a little above room temperature II (0.86 g.) in 5 ml. MeOH treated with 0.6 ml. 25% alc. MeNH2 gave 0.55 g. N-(β-methoxy-α-methylacryloyl)-N’-methylthiourea (XIV), needles, m. 140° (alc.). XIV (0.28 g.) warmed with 2N NaOH gave 0.19 g. 1-methyl-2-thiothymine, needles, m. 226-7° (alc.). Similarly, 0.5 g. II with 0.5 g. PhNH2 in alc. gave 0.6 g. N-(β-methoxy-α-methylacryloyl)-N’-phenylthiourea (XV), m. 110-12° (alc.). XV (0.2 g.) treated with alkali and acidified gave 0.15 g. 1-phenyl-2-thiothymine, needles, m. 202-3°. II (1.12 g.) shaken with 0.54 g. glycine in alkali until a clear solution resulted and then 10-15 min., cooled, acidified, and kept overnight at 0° gave 0.7 g. 1-carboxymethyl-2-thiothymine, needles, m. 246-7° (decomposition) (H2O). V (0.5 g.) in 5 ml. alc. added to 0.68 g. II gave 0.75 g. N1-(β-methoxy-α-methylacryloyl)-N3-phenylthiosemicarbazide (XVI), plates, m. 180-1° (decomposition). XVI (0.31 g.) warmed with 2N NaOH gave 0.28 g. 2,3-didihydro-5-(β-methoxy-α-methylvinyl)-1-phenyl-3-thio-1,2,4-triazole, m. 195-6° (alc.). II (0.935 g.) similarly added to 1.5 ml. MeOH-NH3 gave 0.85 g. N-(β-methoxy-α-methylacryloyl)thiourea (XVII), prisms, m. 163°. XVII was recovered unchanged from its solution in 2N NaOH; longer heating gave H2S and no evidence of pyrimidine formation.
《Purines, pyrimidines, and glyoxalines. VII. New syntheses of 2-thiouracils and 2-thiothymines》 provides a strategy for the preparation of materials with excellent comprehensive properties, which is conducive to broaden the application field of this compound(Ethyl 3-Ethoxy-2-Propenoate)Synthetic Route of C7H12O3.
Reference:
Bromide – Wikipedia,
bromide – Wiktionary