TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Process: In preparing benzodithiophene compound, the monohalogenated dithiophene compound having general formula (II) and the internal alkyne having general formula (III) are used in molar ratios ranging from 1:2 to 1:10. The process relates to the preparation of 4,5-dipropylbenzo(2,1-b:3,4-b') dithiophene corresponding to a benzodithiophene compound having general formula (I) where C and D represent a sulfur atom, A, B, E and F represent a group C-R3 where R3 represents a hydrogen atom, and R1 and R2 represent an n-propyl group, the process comprises reacting 3-bromo-2,2'-dithiophene corresponding to a monohalogenated dithiophene compound having general formula (II) where X represents a bromine atom, C and D represent a sulfur atom and A, B, E and F represent a group C-R3 where R3 represents a hydrogen atom, with 4-octyne corresponding to an internal alkyne having general formula (III) where R1 and R2 represent an n-propyl group. The process relates to the preparation of 4,5-dipropylbenzo(1,2-b:4,3-b') dithiophene corresponding to a benzodithiophene compound having general formula (I) where A and F represent a sulfur atom, B, C, D and E represent a group C-R3 where R3 represents a hydrogen atom, and R1 and R2 represent an n-propyl group, the process comprising reacting 3-bromo-2,2'-dithiophene corresponding to a monohalogenated dithiophene compound having general formula (II) where X represents a bromine atom, A and F represent a sulfur atom and B, C, D and E represent a group C-R3 where R3 represents a hydrogen atom, with 4-octyne corresponding to an internal alkyne having general formula (III) where R1 and R2 represent an n-propyl group. The process is carried out in the presence of at least one weak organic base, where weak organic base is selected from: carboxylates of alkaline or alkaline-earth metals such as potassium acetate, sodium acetate, cesium acetate, magnesium acetate, calcium acetate, potassium propionate, sodium propionate, cesium propionate, magnesium propionate, calcium propionate, or mixtures thereof; carbonates of alkaline or alkaline-earth metals such as lithium carbonate, potassium carbonate, sodium carbonate, cesium carbonate, magnesium carbonate, calcium carbonate, or its mixtures; bicarbonates of alkaline or alkaline-earth metals such as lithium bicarbonate, potassium bicarbonate, sodium bicarbonate, cesium bicarbonate, magnesium bicarbonate, calcium bicarbonate, or its mixtures. The monohalogenated dithiophene compound having general formula (II) and the weak organic base are used in molar ratios ranging from 1:2.2 to 1:20. Preferably, the process is carried out in the presence of at least one catalyst containing palladium. The catalyst containing palladium is selected from: compounds of palladium in oxidation state (0) or(II) such as palladium (II) chloride (PdCl2), palladium (II) acetate (Pd(OAc)2), bis(dibenzylidene) palladium (0) (Pd2(dba)3 where dba=C6H5CH=CHCOCH=CHC6H5), bis-acetonitrile-palladium (II) chloride (Pd(CH3CN)2C12), bis (tri-phenylphosphine) palladium (II) chloride (Pd (PPhs)2C12), bis ( triphenylphosphine)-palladium (II) acetate (Pd (PPh3)2(OAc)2), tetrakis-(triphenylphosphine) palladium (0) (Pd(PPh3)4), or its mixtures. The monohalogenated dithiophene compound having general formula (II) and the catalyst containing palladium are used in molar ratios ranging from 100:0.1 to 100:8; or the monohalogenated dithiophene compound having general formula (II) is used in a molar concentration ranging from 0.05 mmole to 2 mmo1es. The process is carried out in the presence of at least one dipolar aprotic organic solvent, where dipolar aprotic organic solvent is selected from N,N-dimethylacetamide (DMAc), dimethylsulfoxide (DMSO), N-methylpyrrolidone (NMP), N,N-dimethylformamide (DMF), or its mixtures. It is carried out in the presence of at least one quaternary ammonium salt such as a tetraalkylammonium bromide. The monohalogenated dithiophene compound having general formula (II) and the quaternary ammonium salt are used in molar ratios ranging from 1:0.5 to 1:5. The process is carried out in the presence of at least one lithium salt such as lithium bromide, lithium chloride. The monohalogenated dithiophene compound having general formula (II) and the lithium salt are used in molar ratios ranging from 1:0.5 to 1:5. The process is carried out at a temperature ranging from 80 degrees C to 170 degrees C. It is carried out for a time ranging from 30 minutes to 72 hours. EXAMPLE - No suitable example given.