The phrase "almost insoluble" is correct and usable in written English.
It can be used to describe a problem or situation that is very difficult to solve, but not entirely impossible.
Example: "The mathematical equation presented in the lecture was almost insoluble, leaving many students frustrated."
Alternatives: "nearly unsolvable" or "practically impossible".
It is almost insoluble in water.
Boxing has an almost insoluble dilemma.
On the opposite, synthetic analogs with a large hydrophobic part may be almost insoluble in water.
It is a colourless, waxy solid that is almost insoluble in water.
I mean, you do have these incredibly profound equity issues that are on the table and by some accounts [are] almost insoluble.
Such consolidation avoided the almost insoluble perils of farflung elements trying to maintain togetherness and probably helped make this the honestly prepared and relatively clean presentation it was.
Cadmium pigments are almost completely insoluble, so you won't get cadmium poisoning from drinking coffee out of a glazed mug.
Given that the doxorubicin dimer is almost water insoluble and that its azomethine bond may readily be cleaved to restore the doxorubicin monomer, the later stage of sustained drug release may involve regenerated doxorubicin in addition to the doxorubicin dimer itself[30].
Two alleles (V910D and L939P) were found to be almost completely insoluble when expressed in bacteria (data not shown), in contrast to wild-type OPA1-S1.
Since MTX was an aromatic compound that was almost water insoluble, its hydrophobic nature and aromatic structure benefited its tight incorporation with the hydrophobic segment of the polymeric micelles and π- π stacking with the phenyl of PAA in the micelle core.
Aqueous emulsion homo- and copolymerization of lauryl methacrylate (LMA), a highly hydrophobic, almost water-insoluble monomer, is quite challenging.
