Steinkopf, Wilhelm; Kohler, Werner published the artcile< Thiophene series. XXXVIII. Chlorine derivatives of thiophene and the limited usefulness of mixed melting points with the isomeric thiophene derivatives>, Application In Synthesis of 31166-29-7, the main research area is .
The fraction of 2-chlorothiophene (I) b. 130-6° yields a chloromercuri derivative (II), m. 223-4°; distillation with 10% HCl gives 86% of pure I, b. 127-8.3° (corrected), m. -70° to -69°, nD19 1.55058. II and I in KI give 67% of 5-chloro-2-iodothiophene, b14 95-6°, m. -25° to -24° (corrected). Refluxing I with yellow HgO in AcOH for 4 h. gives the 3,4,5-tri(acetoxymercuri) complex, transformed by NaCl into the corresponding Cl derivative and this in turn by I in KI into 80% of 2-chloro-3,4,5-triiodothiophene m. 126°; this also results by the action of I upon I in the presence of Hg(OAc)2. I and Br give 80-5% of the 3,4,5-tri-Br derivative, m. 91°. With ClSO3H at -10°, 8 g. I yields 2.4 g. of the 5-sulfonyl chloride, m. 28°. I is separated from III by means of the II derivative, since III does not react with HgCl2. 2,5-Dichlorothiophene (III), b. 161-2°, m. -43.4° (corrected), nD19 1.56077, is purified through the 3,4-bis(chloromercuri) derivative (IV), m. 314-15° (prepared with HgO in AcOH, followed by NaCl). IV and I-KI give the 3,4-di-I derivative (V), m. 83°, and, as an Et2O-insoluble fraction, 2,5,2′,5′-tetrachloro-3,3′-diiodo-4,4′-mercurydithienyl, m. 238°. III and Br give 80% of the 3,4-di-Br derivative, m. 65°. I and AcCl in petr. ether with AlCl3 give 16% of 2,5-dichloro-3-acetothienone, m. 39°. VI, transformed into the Grignard reagent with EtMgBr and reacted with CO2, gives a very small yield of 2,5-dichlorothiophene-3,4-dicarboxylic acid, sublimes about 200°; melting with m-C6H4(OH)2 and ZnCl2 gives a strong green fluorescence. The trichlorothiophene fraction, b. 203-7°, with HgO in AcOH, yields 80% of 2,3,5,2′,3′,5′ -hexachloro-4,4′-mercurydithienyl (VII), m. 242-3°, which has a pale violet color in UV light. VII and HgCl2 in Me2CO yield 89% of 2,3,5-trichloro-4-chloromercurithiophene, m. 211-12°; heating with HCl gives 77% of 2,3,5-trichlorothiophene (VIII), b. 207.7-9.2° (corrected), m. -3.5°, nD19.3 1.58515. The 4-bromomercuric derivative of VIII m. 207° (quant. yield from VII) and has a pale blue-violet color in UV light. VIII gives 90% of the 4-Br derivative, m. 50.5-1.5°, and a quant. yield of the 4-I derivative, m. 51°; both are soluble in 33% oleum with a deep bluish green color. Crude VIII and AcCl with AlCl3 in petr. ether yield 6.5% of 2,3,5 trichloro-4-acetothiophene, m. 80°. VIII and HNO3 in concentrated H2SO4 give the 4-NO2 derivative, m. 70°. Chlorination of 2,5-dibromo-3-iodo-4-thiophenic acid in AcOH yields 2,3,5-trichloro-4-thiophenic acid, m. 176-7°. The 4-sulfonyl chloride of VIII m. 57-8°. The action of EtMgBr upon tetrachlorothiophene gives 2,3,4-trichlorothiophene (IX), b. 209.2-10.2° (corrected), m. -0.5°, nD19.1 1.58588, purified through the 5-chloromercuri derivative (X), m. 211° (18% yield). With HgO in AcOH IX yields 50-5% 2,3,4,2′,3′,4′-hexachloro-5-mercurydithienyl, m. 242-3°, color in UV light bright violet; this also results from X and NaI in Me2CO; with HgBr2 there results a nearly quant. yield of the 5-bromomercuri derivative of IX, m. 207°. X, I and KI give a quant. yield of the 5-I derivative of IX, m. 50-1°, easily colored red by light; the 5-Br derivative, m. 50.5°, results from X and Br-H2O-KBr or from IX and Br2. IX and AcCl with AlCl3 give 59% of 2,3,4-trichloro-5-acetothienone, m. 80°, shows a bright yellow color in UV light. The 5-NO2 derivative of IX, pale yellow, m. 70°. The 5-sulfonyl chloride m. 55-6° (59% yield). 2,3-Dibromo-5-thiophenic acid and Cl2 in AcOH give 2,3-dichloro-5-thiophenic acid, m. 196-7°, sublimes at 120°; boiling with Hg(OAc)2 in AcOH for 3 h. gives 2,3-dichloro-4,5-bis(acetoxymercuri)thiophene (XI), which, transformed into the chloromercuri derivative (XIA), and distilled with HCl, gives 2,3-dichlorothiophene (XII), b. 173-4°, m. -26.2° (corrected), nD21 1.56650; 5-chloromercuri derivative, m. 269-70°; 5-I derivative, m. 27°; 5-Br derivative (XIII), b. 212-14°, m. 6°. 2,3-Dichloro-5-acetothienone, m. 68° (47% yield). XIII and HgO in AcOH, refluxed 5 h., the product treated with NaCl and then with NaI, give 2,3,2′,3′-tetrachloro-5,5′-dibromo-4,4′-mercurydithienyl, m. 238-9°. XII and HNO3 in Ac2O give 37% of the 5-NO2 derivative, pale yellow, m. 55-6°. The 5-sulfonyl chloride (XIV), pale yellow, m. 55-6° (81%). XI or XIA with KI-I gives the 4,5-di-I derivative of XII, m. 72°; XII and Br2 gives 88% of the 4,5-di-Br derivative, m. 67.5°. Heating XIV with a slight excess of 15% NaOH and reduction of the filtrate with 2.5% Na-Hg give 8.4% of 3-chlorothiophene (XV), b. 136-7° (corrected), m. -62°, nD22 1.55322; 2-chloromercuri derivative, m. 137-8°; 2,5-bis(chloromercuri) derivative, decomposes 275°. 3,3′-Dichloro-2,2′-mercurydithienyl, m. 174-5°. XII and EtMgBr, followed by CO2, give 2.8% of 3-chloro-2-thiophenic acid, m. 175-6°. Heating XV with Hg(OAc)2 in AcOH for a short time, then gradually adding I, gives 85% of 3-chloro-2,4,5-triiodothiophene, m. 121°; 2,4,5-triBr derivative, m. 91° (90% yield). The mother liquor from the preparation of XV appears to contain 4-chlorothiophene-2-sulfonic acid, for with PCl5 there results 10% of 2,4-dichlorothiophene, b. 174-5°, m. -34°, nD21.7 1.56866; 3,5-di-Br derivative, m. 72° (85%). Treating 2,5-thioxene with Cl in CCl4 and the residual oil reacted with Br2 give 60% of 3,4 – dichloro – 2,5 – bis(dibromomethyl)thiophene (XVI), m. 112°; in boiling CCl4 Cl2 gives the bis(dichloromethyl) analog, m. 80°. XVI and CaCO3 in H2O, heated 8 h., give 95% of 3,4-dichlorothiophene-2,5-dialdehyde, pale yellow, m. 194°; alk. H2O2 gives a small amount of 3,4-dichlorothiophene-2-aldehyde, with 0.5 mol. H2O, m. 72°, the principal product being the 2,5-dicarboxylic acid (XVII), m. 314-15° (decomposition). XVII, transformed into the 2,5-bis(acetoxymercuri) and then into the chloromercuri derivative and distilled with dilute HCl, yields 65% of 3,4-dichlorothiophene, b. 184.5-5.5°, m. 1°, nD19.6 1.58206; 2 -chloromercuri derivative, m. 206-7°; 2,5-bis(chloromercuri) derivative, m. 347-9°; 2,5-di-I derivative, m. 106°; 2,5-di-Br derivative, m. 75°. AcCl gives 88% of 3,4-dichloro-2-acetothienone, m. 56°. 3,4-Dichloro-2,5-bis(dibromomethyl)thiophene and Na2CO3 give a poor yield of 3,4-dichloro-2-hydroxymethylthiophene-5-carboxylic acid, m. 220-1°. 2,4,5-Tribromo-3-thiotolene and Cl2 in CCl4 give 3,4-dichloro-2,5-bis(dichloromethyl)thiophene, which yields with EtOH-KOH 2,4,5-trichloro-3-thiotolene, b23 115-16°, m. -18° (corrected), nD21.5 1.56617. 2,4,5-Triiodo-3-thiotolene and Cl2 in CHCl3 (with cooling), followed by EtOH-KOH, give 3-methyl-2,2,3,4,4,5,5-heptachlorotetrahydrothiophene, m. 217-18.5°. Exhaustive chlorination of thiophene or 2-thiophenic acid in AcOH gives 2,3,3,4,5(or 2,2,3,4,5)pentachloro-2,3-dihydrothiophene, b13 122-6°. 2,5-Thioxene and Br2 in CS2 give 85% of 3,4-dibromo-2,5-bis(dibromomethyl)thiophene, m. 132°; Cl2 gives a quant. yield of the dichloromethyl analog, m. 103°; CaCO3 in H2O gives 3,4-dibromothiophene-2,5-dialdehyde, pale yellow, m. 227°; aqueous KMnO4 gives 45% of the 2,5-dicarboxylic acid, m. 317-18°; long treatment with Cl2 in AcOH gives 49% of the acid. 2,3-Dibromo-5-thiophenic acid gives with Hg(OAc)2 in AcOH, followed by formation of the chloromercuri salt and distillation with dilute HCl, 2,3-dibromothiophene, b. 218.6-19.6°, m. -17.5°, nD22.8 1.63039. 2-Thiotolene and Br2-H2O give the tetra-Br derivative, m. 115-17°. The mixed m. ps. of isomeric thiophene derivatives are discussed and illustrated by several examples, showing that this method cannot be used to distinguish the higher halogenated derivatives Certain thiophene and selenophene derivatives have approx. the same m. ps. and mixed m. ps. The possibility of using luminescent anal. for distinguishing between these derivatives is also discussed.
Justus Liebigs Annalen der Chemie published new progress about Melting point. 31166-29-7 belongs to class chlorides-buliding-blocks, and the molecular formula is C5H2Cl2O2S, Application In Synthesis of 31166-29-7.
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