{"knowledge_schema": {"broad_category": "Chemistry \u2192 Organic Chemistry \u2192 Synthesis", "refinement": "This problem focuses on the synthesis of alkenes using the Wittig reaction, which involves the reaction of an aldehyde or ketone with a phosphonium ylide.", "specific_scope": "The task is to identify the correct starting materials needed to synthesize a specific alkene, 2,5-dimethyl-3-hexene, through the Wittig reaction.", "goal": "Select the appropriate aldehyde or ketone and phosphonium salt that will yield the desired alkene product."}, "summary": "This problem involves organic chemistry, specifically the synthesis of alkenes using the Wittig reaction. The goal is to identify the correct starting materials needed to synthesize 2,5-dimethyl-3-hexene. The correct answer is 2,5-dimethylhexanal and methyltriphenylphosphonium bromide, as this combination will yield the desired alkene through the reaction mechanism of the Wittig process."}