- RU-58841 is a lipophilic small molecule: poorly soluble in water, soluble in ethanol and in ethanol/propylene glycol co-solvents.
- Supplier-published ethanol solubility ranges from 33 mg/mL (Cayman Chemical) to 74 mg/mL (Selleck Chemicals), so a 50 mg/mL solution sits inside the disputed range and needs deliberate dissolving.
- Near-saturated solutions can crystallise in the cold. It re-dissolves with gentle warming and is not degradation.
- The molecule is photosensitive: amber glass, cool and dark.
- Neither RU-58841 nor any material on this page is approved for human use. This is a laboratory reference only.
- Use a non-aqueous vehicle. Ethanol with propylene glycol is the common choice; water alone will not hold it.
- Weigh accurately, add solvent in stages, and give it time. Rushed dissolving is the main reason solutions end up weaker than labelled.
- Store in amber glass, cool and dark, and warm gently if crystals appear.
What does RU58841 powder dissolve in?
RU-58841 is a nonsteroidal small molecule with high lipophilicity, so it behaves like many organic reference compounds: it dissolves in organic solvents and barely at all in water. In the published animal work and in laboratory practice the usual vehicle is ethanol, frequently blended with propylene glycol, which lowers volatility and helps keep the compound in solution. Our own reference solution is made in a 70/30 ethanol to propylene glycol vehicle. For background on the molecule itself see What Is RU58841?
How much will dissolve, and why does it matter?
Published ethanol solubility varies between sources: Cayman Chemical lists 33 mg/mL and Selleck Chemicals lists 74 mg/mL. A 50 mg/mL (5%) preparation falls between the two, so there is little or no headroom. Two practical consequences follow. First, anything made above the ceiling will not fully dissolve, and the undissolved fraction is lost from the measured concentration. Second, the exact limit moves with temperature and with the water content of the solvent, so a single number should be treated as approximate. Both points explain why cheaply made solutions are often weaker than their label.
Dissolving technique for laboratory preparation
- Weigh by mass on a calibrated balance. Volume-based shortcuts introduce the largest errors at this concentration.
- Add the solvent in stages rather than all at once, and let each addition fully wet the powder.
- Use gentle, not aggressive, warming. Mild warmth speeds dissolving. Strong heat risks solvent loss and degradation.
- Check clarity against a light. A clear solution with no visible particles is the target. Cloudiness or settling means it has not dissolved.
- Use dry, high-purity solvents. Water in the ethanol reduces solubility.
Why do solutions crystallise?
Near saturation, a drop in temperature lowers solubility and the excess comes out as crystals. This is a reversible physical change. Warming gently re-dissolves it. It is not a sign that the compound has degraded, though repeated cold cycles are worth avoiding for a stock solution.
Light and storage
The molecule is photosensitive. Stock solutions belong in amber, UV-attenuating glass with a tight closure, kept cool and dark. More detail in How to store RU58841.
Checking what you actually have
Dissolving correctly only matters if the starting material is what it claims to be. A named laboratory, a checkable report ID and a batch number that matches the label are what to look for. Our checklist is in choosing a supplier.
Research use only
RU-58841 is not an approved medicine anywhere. This page describes laboratory handling of a reference material. It is not guidance for human or animal use, and it makes no claim about any effect.