Answer to Question #63047 in General Chemistry for Anahita

Question

Which is more soluable in water ? Methylcellolose or Ethylcellolose?

Answer 1

Methylcellulose dissolves in cold water unlike of ethylcellolose.
But In comparison with methylcellulose, ethylcellulose becomes water-soluble at lower degree of substitution (it's about 1,2 in comparison with 1,8 in case of good solubility). Large ethyl groups move apart cellulose chain molecules quite more than methyl one causing even greater weakening of crystal packing forces among the chain molecules and allowing molecules of water to hydrate and disperse them.
In Methylcellulose higher DS(degree of substitution)-values result in lower solubility, because the polar hydroxyl groups are masked. The chemical is not soluble in hot water, which has the paradoxical effect that heating a saturated solution of methylcellulose will turn it solid, because methylcellulose will precipitate out. The temperature at which this occurs depends on DS-value, with higher DS-values giving lower precipitation temperatures.