Gronowitz, Salo et al. published their research in Acta Chemica Scandinavica in 1962 | CAS: 29421-99-6

4-Bromo-5-methylthiophene-2-carboxylic acid (cas: 29421-99-6) belongs to organobromine compounds. Many of the organo bromine compounds are relatively nonpolar. Bromine is more electronegative than carbon (2.8 vs 2.5) and hence the carbon in a carbon–bromine bond is electrophilic in nature. One prominent application of synthetic organobromine compounds is the use of polybrominated diphenyl ethers as fire-retardants, and in fact fire-retardant manufacture is currently the major industrial use of the element bromine.Application of 29421-99-6

Optically active bithienyls. II. Synthesis and resolution of2,2′-dicarboxy-4,4′-dibromo-5,5′-dimethyl-3,3′-bithienyl was written by Gronowitz, Salo;Frostling, Harold. And the article was included in Acta Chemica Scandinavica in 1962.Application of 29421-99-6 This article mentions the following:

Atropisomerism has been demonstrated for the first time in the 3,3′-bithienyl series. 4-Bromo-2-thiophenealdehyde (202 g.), 200 ml. 99% N2H4.H2O, and 500 ml. ethylene glycol was heated at 130-140° and H2O and excess hydrazine distilled The solution was cooled, 200 g. KOH added, and the mixture heated to 90° until a vigorous reaction occurred, then heated an addnl. 15 min., steam distilled, and extracted with Et2O to yield 167 g. 4-bromo-2-methylthiophene (I), b11 61-2°, n20D 1.5725. To 160 g. I in 150 ml. anhydrous Et2O was added 1300 ml. 0.9N BuLi at -70°. After 5 min. 134 g. anhydrous CuCl2 was added and the mixture stirred 3 hrs. at -70°. After 3 hrs. at room temperature the product was worked up to give 19 g. 5,5′-dimethyl-3,3′-bithienyl (II), m. 135-6° (ligroine). BuLi (500 ml., 0.9N) was added to 18.5 g. II in 300 ml. dry Et2O and the mixture refluxed for 2 hrs., poured on solid CO2 in Et2O, and hydrolyzed at -10° with H2O. The Et2O phase yielded 12 g. 2,2′-dicarboxy-5,5′-dimethyl-3,3’bithienyl (III), m. 254-7° (decomposition) (HOAc). An excess of Br was poured on 7.0 g. III. The Br was evaporated, and the residue heated with 200 ml. Na2CO3, filtered, and acidified with 2N HCl. The crude acid was recrystallized from HOAc to yield 8.5 g. 2,2′-dicarboxy-4,4′-dibromo-5,5′-dimethyl-3,3′-bithienyl (IV), m. 311-13° (decomposition); di-Me ester m. 15-46° (EtOH). 4-Bromo-5-methyl-2-thiophenecarboxylic acid was prepared by bromination of 5-methyl-2-thiophenecarboxylic acid in HOAc, m. 197-8° (aqueous EtOH). Fractional crystallization of the cinchonine salt of IV from aqueous EtOH resulted in a separation of the optical antipodes (+)-IV, m. 302-5° (decomposition),[α]25D 43° (aqueous EtOH), and (-)-IV, m. 301-4° (decomposition), [α]25D -43° (aqueous EtOH). The rotations of (+)-IV in other solvents were as follows (solvent and [α]25D given): acetone, 43°; Me2SO, 53°, EtOH, 55°; CHCl3, -57.5°; 0.1N NaOH, -1.90°. In the experiment, the researchers used many compounds, for example, 4-Bromo-5-methylthiophene-2-carboxylic acid (cas: 29421-99-6Application of 29421-99-6).

4-Bromo-5-methylthiophene-2-carboxylic acid (cas: 29421-99-6) belongs to organobromine compounds. Many of the organo bromine compounds are relatively nonpolar. Bromine is more electronegative than carbon (2.8 vs 2.5) and hence the carbon in a carbon–bromine bond is electrophilic in nature. One prominent application of synthetic organobromine compounds is the use of polybrominated diphenyl ethers as fire-retardants, and in fact fire-retardant manufacture is currently the major industrial use of the element bromine.Application of 29421-99-6

Referemce:
Bromide – Wikipedia,
bromide – Wiktionary