A hydrophile is a molecule or other molecular unit that is attracted to water molecules and becomes dissolved by water. In contrast, hydrophobes are not attracted to water and may seem to be repelled by it. Hygroscopics are attracted to water, but are not dissolved by water.
Molecules
A hydrophilic molecule or part of a molecule is one whose interactions with water and other polar substances are more thermodynamically favorable than their interactions with oils or other hydrophobic solvents . [2] [3] They are generally charge-polarized and capable of hydrogen bonding . This makes these molecules soluble not only in water but also in other polar solvents .
Hydrophilic molecules (and portions of molecules) can be contrasted with hydrophobic molecules (and portions of molecules). In some cases, the same molecule has both hydrophilic and hydrophobic properties. An example of these amphiphilic molecules are lipids that comprise the cell membrane . Another example is soap , which has a hydrophilic head and a hydrophobic tail, which allows it to dissolve in both water and oil.
Hydrophilic and hydrophobic molecules are also known as polar molecules and non- polar molecules respectively. Some hydrophilic substances do not dissolve. Such a mixture is called a colloid .
An approximate rule of thumb for the hydrophilicity of organic compounds is that the solubility of a molecule in water is greater than 1 % by mass if there is at least one neutral hydrophile group per 5 carbons, or at least one electrically charged hydrophile. There are 7 carbons per group. [4]
Hydrophilic substances (ex: salts) can attract water from the air. Sugar is also hydrophilic, and like salt is sometimes used to remove water from foods. Sugar sprinkled on cut fruit will “draw out water” through the hydrophilia, making the fruit soft and moist, as in a typical strawberry compote recipe.
Chemicals
Liquid hydrophilic chemicals complexed with solid chemicals can be used to optimize the solubility of hydrophobic chemicals.
Liquid chemicals
Examples of hydrophilic liquids include ammonia, alcohols, some amides such as urea, and some carboxylic acids such as acetic acid.
Alcohol
The hydroxyl groups (-OH) found in alcohols are polar and therefore hydrophilic (water liking), but their carbon chain part is non-polar which makes them hydrophobic. The molecule rapidly becomes overall more nonpolar and therefore less soluble in polar water as the carbon chain becomes longer. [5] Methanol has the shortest carbon chain of all alcohols (one carbon atom), followed by ethanol (two carbon atoms), and 1-propanol as well as its isomer 2-propanol , all miscible with water. There are. Tert-butyl alcohol , with four carbon atoms, with waterIt’s the only one of its isomers to be wrong .
Solid chemicals
Cyclodextrin
Cyclodextrin is used to make pharmaceutical solutions by holding hydrophobic molecules as a guest host. Because the inclusion compounds of cyclodextrins with hydrophobic molecules are able to penetrate body tissues, they can be used to release biologically active compounds under specific conditions. [6] For example, the Joseph Pitha study showed that when testosterone was complexed with hydroxy-propyl-beta-cyclodextrin (HPBCD), 95% absorption of testosterone via the sublingual route was achieved in 20 min. but HPBCD was not absorbed, whereas generally less than 40% of hydrophobic testosterone is normally absorbed via the sublingual route.
Membrane filtration
Hydrophilic membrane filtration is used in many industries for filtering various liquids. These hydrophilic filters are used in medical, industrial and biochemical fields to filter bacteria, viruses, proteins, particulates, drugs and other contaminants. Common hydrophilic molecules include colloids, cotton, and cellulose (which contains cotton).
Unlike other membranes, hydrophilic membranes do not require pre-wetting: they can filter liquids in their dry state. Although most are used in low-heat filtration processes, many newer hydrophilic membrane fabrics are used to filter hot liquids and liquids.
