How does the presence of the methyl group affect the properties of organic molecules?

The presence of a methyl group in organic molecules plays a significant role in influencing their properties, and it can indeed alter solubility and reactivity. Methyl groups, being hydrophobic (water-repelling), can affect the solubility of a molecule in polar solvents like water. Molecules with more methyl groups tend to be less soluble in water because the hydrophobic nature of the methyl group does not interact favorably with polar molecules, leading to decreased solubility.

Furthermore, methyl groups can influence reactivity through steric effects and electronic effects. For instance, the introduction of a methyl group can hinder or promote the approach of reactants during a reaction due to its size, thus affecting reaction rates. Additionally, methyl groups can impact the stability of intermediates in chemical reactions, which subsequently alters the reaction pathways.

Overall, the introduction of a methyl group can significantly modify both the physical and chemical properties of organic compounds, making it correct to say that it can alter solubility and reactivity.