Science desk
< July 2	<< Jun \| July \| Aug >>	July 4 >

Welcome to the Wikipedia Science Reference Desk Archives
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.

July 3

Solubility of sugar(s) in sodium /alkali metal halides

What data are available for solubilities of sucrose in solutions of sodium chloride and other alkali metal halides of various concentrations of these salts included saturated ones? (Thanks!) --109.166.139.165 (talk) 15:02, 3 July 2019 (UTC)[reply]

A similar question for glucose and fructose! --109.166.139.165 (talk) 15:05, 3 July 2019 (UTC)[reply]

The general concept of reducing the solubility of an organic molecule through the addition of salt is known as salting out. This is normally described for precipitating large molecules like DNA or protein, though it can be done for much smaller molecules as well. However, I have not seen any literature describing salting-out conditions for simple sugars. Someguy1221 (talk) 01:42, 4 July 2019 (UTC)[reply]

Found a ref:

Young, R. A. (1898). "The Precipitation of Carbohydrates by Neutral Salts". 22 (5): 401–422. doi:10.1113/jphysiol.1898.sp000703. {{cite journal}}: Cite journal requires |journal= (help)

that reports an "extended investigation of the action of neutral salts on carbohydrate solutions". Among its conclusions is that "ordinary crystalline carbohydrates, dextrose, laevulose, cane sugar, maltose, and lactose were all investigated, but as was expected with uniformly negative results as far as precipitation was concerned." It does report that some other types of carbohydrates can be salted out. Interestingly, it also notes that the crystalline carbohydrates form complexes with some salts, and that most of these complexes are crystalline. For example, I was surprised to learn that sucrose·NaCl·H₂O is a known substance since the late 1800s! If the carb complexes with the salt, I'm not surprised that it's not going to lead to precipitation of the carb itself. DMacks (talk) 02:40, 4 July 2019 (UTC)[reply]