Glucose Molecular Formula and Facts

The molecular formula for glucose is C6H12O6 or H-(CO)-(CHOH)5-H. Its empirical or simplest formula is CH2O, which indicates there are two hydrogen atoms for each carbon and oxygen atom in the molecule. Glucose is the sugar that is produced by plants during photosynthesis and that circulates in the blood of people and other animals as an energy source. Glucose is also known as dextrose, blood sugar, corn sugar, grape sugar,  or by its IUPAC systematic name  (2R,3S,4R,5R)-2,3,4,5,6-Pentahydroxyhexanal. Key Takeaways: Glucose Formula and Facts Glucose is the most abundant monosaccharide in the world and the key energy molecule for Earths organisms. It is the sugar produced by plants during photosynthesis.Like other sugars, glucose forms ismomers, which are chemically identical, but have different conformations. Only D-glucose occurs naturally. L-glucose may be produced synthetically.The molecular formula of glucose is C6H12O6. Its simplest or empirical formula is CH2O. Key Glucose Facts The name glucose comes from the French and Greek words for sweet, in reference to must, which is the sweet first press of grapes when they are used to make wine. The -ose ending in glucose indicates the molecule is a carbohydrate.Because glucose has 6 carbon atoms, it is classified as a hexose. Specifically, it is an example of an aldohexose. It is a type of monosaccharide or simple sugar. It may be found in either linear form or cyclic form (most common). In linear form, it has a 6-carbon backbone, with no branches. The C-1 carbon is the one bearing the aldehyde group, while the other five carbon each bear a hydroxyl group.The hydrogen and -OH groups are able to rotate around the carbon atoms in glucose, leading to isomerization. The D-isomer, D-glucose, is found in nature and is used for cellular respiration in plants and animals. The L-isomer, L-glucose, is not common in nature, although it may be prepared in a lab.Pure glucose is a white or crystalline powder with a molar mass of 180.16 grams per mole and density of 1.54 grams per cubic centimeter. The melting point of the solid depends on whether it is in the alpha or beta conformation.  The melting point of  ÃŽ ±-D-glucose is  146  Ã‚ °C (295  Ã‚ °F; 419  K). The melting point of  ÃŽ ²-D-glucose is  150  Ã‚ °C (302  °F; 423 K).Why do organisms use glucose for respiration and fermentation rather than another carbohydrate? The reason is probably that glucose is less likely to react with the amine groups of proteins. The reaction between carbohydrates and proteins, called glycation, is a natural part of aging and consequence of some diseases (e.g., diabetes) that impairs the functioning of proteins. In contrast, glucose may be enzymatically added to proteins and lipids via the process of glycosylation, which forms active glycolipids and glycoproteins.In the human body, glucose supplies about 3.75 kilocalories of energy per gram. It is metabolized into carbon dioxide and water, producing e nergy in chemical form as ATP. While its needed for many functions, glucose is particularly important because it supplies nearly all the energy for the human brain.Glucose has the most stable cyclic form of all the aldohexoses because nearly all of its hydroxy group (-OH) are in the equatorial position. The exception is the hydroxy group on the anomeric carbon.Glucose is soluble in water, where it forms a colorless solution. It also dissolves in acetic acid, but only slightly in alcohol.The glucose molecule was first isolated in 1747 by the German chemist Andreas Marggraf, who obtained it from raisins. Emil Fischer investigated the structure and properties of the molecule, earning the 1902 Nobel Prize in Chemistry for his work. In the Fischer projection, glucose is drawn in a specific configuration. The hydroxyls on C-2, C-4, and C-5 is on the right side of the backbone, while the C-3 hydroxyl is on the left side of the carbon backbone. Sources Robyt, John F. (2012). Essentials of Carbohydrate Chemistry. Springer Science Business Media. ISBN:978-1-461-21622-3.Rosanoff, M. A. (1906). On Fischers Classification of Stereo-Isomers. Journal of the American Chemical Society. 28: 114–121. doi:10.1021/ja01967a014Schenck, Fred W. (2006). Glucose and Glucose-Containing Syrups. Ullmanns Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a12_457.pub2