Final answer:
OsO4 addition to a cis alkene produces a cis diol, with both OH groups on the same side, while addition to a trans alkene produces a trans diol, with OH groups on opposite sides, due to cis/trans stereoisomerism.
Step-by-step explanation:
The products formed by OsO4 addition to a cis alkene vs a trans alkene are diols, which are molecules with two hydroxyl groups (-OH). OsO4, or osmium tetroxide, is a reagent used in organic chemistry to carry out dihydroxylation, adding OH groups to each carbon of a carbon-carbon double bond. When added to a cis alkene, OsO4 creates a cis diol, where the hydroxyl groups end up on the same side of the molecule. Conversely, when reacted with a trans alkene, a trans diol is formed, with the hydroxyl groups on opposite sides of the molecule. The stereochemistry of the alkene determines the stereochemistry of the product diol, preserving the original geometric relationship between substituents on the carbon atoms involved in the double bond.
The difference in the products is due to the inherent cis/trans stereoisomerism that occurs in alkenes and influences the physical and chemical properties of the resultant compounds. In biological systems, most naturally occurring double bonds in compounds such as fatty acids are in the cis configuration, which has significant consequences for biological function and nutrition.