Carbohydrates carbon dioxide, reaction with

Carbohydrates, allyloxycarbonates, 123 carbonates of, 151 chloroformyl esters of, 102 conformational analysis of, 12 reaction of, with carbon dioxide, 129 with carbon disulfide, 135 with carbonic acid, 129 with phosgene in acetone, 105 thermochemical properties of, 21 thiocarbonates of, 157 Carbonic acid, esters, 91,92,151 bis(methyl 3,4-0-isopropylidene-/3-D-arabinopyranoside), 2,2 -, 96 bis(1,2,3,4 - tetra - O - acetyl -/J - D - glucose), 6,6 -, 104 cyclic, 103... 

Electron-transfer reactions occur all around us. Objects made of iron become coated with mst when they are exposed to moist air. Animals obtain energy from the reaction of carbohydrates with oxygen to form carbon dioxide and water. Turning on a flashlight generates a current of electricity from a chemical reaction in the batteries. In an aluminum refinery, huge quantities of electricity drive the conversion of aluminum oxide into aluminum metal. These different chemical processes share one common feature Each is an oxidation-reduction reaction, commonly called a redox reaction, in which electrons are transferred from one chemical species to another. 

Photosynthesis is the reverse of reaction (30.1) the formation of carbohydrates and oxygen from water and carbon dioxide with solar energy. Photosynthesis occurs in the chloroplasts contained in the cells of green plants. The chloroplasts hold two types of photosynthetic systems, which are called PSl and PS 11. These systems... 

The analytical phase generally involves the use of very dilute solutions and a relatively high ratio of oxidant to substrate. Solutions of a concentration of 0.01 M to 0.001 M (in periodate ion) should be employed in an excess of two to three hundred percent (of oxidant) over the expected consumption, in order to elicit a valid value for the selective oxidation. This value can best be determined by timed measurements of the oxidant consumption, followed by the construction of a rate curve as previously described. If extensive overoxidation occurs, measures should be taken to minimize it, in order that the break in the curve may be recognized, and, thence, the true consumption of oxidant. After the reaction has, as far as possible, been brought under control, the analytical determination of certain simple reaction-products (such as total acid, formaldehyde, carbon dioxide, and ammonia) often aids in revealing what the reacting structures actually were. When possible, these values should be determined at timed intervals and be plotted as a rate curve. A very useful tool in this type of investigation, particularly when applied to carbohydrates, has been the polarimeter. With such preliminary information at hand, a structure can often be proposed, or the best conditions for a synthetic operation can be outlined. 

A method for the determination of formaldehyde in the presence of acetaldehyde was developed by Nicolet and Shinn.88,100 103 After the excess periodate had been destroyed, these workers swept the acetaldehyde (from the neutral reaction mixture) into a sodium bisulfite solution by means of a stream of carbon dioxide. The acetaldehyde was measured by conventional, bisulfite methods, and the residual formaldehyde was precipitated with Dimedon. This procedure was applied to protein hydroly-zates and to terminal deoxy structures of carbohydrates.88,280 ... 

Atrazine enters plants primarily by way of the roots and secondarily by way of the foliage, passively translocated in the xylem with the transpiration stream, and accumulates in the apical meristems and leaves (Hull 1967 Forney 1980 Reed 1982 Wolf and Jackson 1982). The main phytotoxic effect is the inhibition of photosynthesis by blocking the electron transport during Hill reaction of photosystem II. This blockage leads to inhibitory effects on the synthesis of carbohydrate, a reduction in the carbon pool, and a buildup of carbon dioxide within the leaf, which subsequently causes closure of the stomates, thus inhibiting transpiration (Stevenson et al. 1982 Jachetta et al. 1986 Shabana 1987). 

Lighting a match means initiating a simple combustion reaction. Carbohydrates in the wood combine chemically with oxygen in the air to form water and carbon dioxide. The amount of heat liberated is so great that it catches hre (causing the water to form as steam rather than liquid water). 

But why do they bum wood, say, when cold The principal reactions occurring when natural materials bum involve chemical oxidation, with carbohydrates combining with elemental oxygen to yield water and carbon dioxide. Nitrogen... 

Dark reactions the short-term chemical energy is used to convert carbon dioxide into carbohydrate. We will not be concerned with these dark reactions. 

The light independent reactions take place in the stroma with the help of ATP and NADPH. In a process called the Calvin-Benson cycle, or carbon fixation, carbon dioxide from the atmosphere is captured and converted into carbohydrates [135]. The reaction is catalyzed by the enzyme RuBisCO (ribulose-1,5-biphosphate... 

The reaction of potassium chlorate with a carbohydrate (e.g., lactose) will produce carbon monoxide (CO), carbon dioxide (CO2 I or a mixture depending on the oxidizerifuel ratio. The balanced equations are given as equations 8.2 and 8. 3. (Lactose occurs as a hydrate - one water molecule crystallizes with each lactose molecule.)... 

Neutralization of a potassium hydroxide adduct of amylose with gaseous carbon dioxide leads to a potassium hydrogen carbonate adduct. This type of reaction, which is rapid in a moist atmosphere, could possibly be used in the preparation of bicarbonate adducts of other carbohydrates. 

Claisen reactions involving acetyl-CoA are made even more favourable by first converting acetyl-CoA into malonyl-CoA by a carboxylation reaction with CO2 using ATP and the coenzyme biotin (Figure 2.9). ATP and CO2 (as bicarbonate, HC03-) form the mixed anhydride, which car-boxy lates the coenzyme in a biotin-enzyme complex. Fixation of carbon dioxide by biotin-enzyme complexes is not unique to acetyl-CoA, and another important example occurs in the generation of oxaloacetate from pyruvate in the synthesis of glucose from non-carbohydrate sources... 

The dark reactions (carbon-fixation reactions) use the ATP and NADPH produced by the light reactions to fix carbon dioxide as carbohydrate sucrose and starch. The reactions form a cycle (the Calvin cycle) in which the enzyme ribulose bisphosphate carboxylase (rubisco), located in the stroma, condenses a C02 molecule with ribulose 1,5-bisphosphate to produce two molecules of 3-phosphoglycerate. Other reactions then regenerate the ribulose... 

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