Greenhouse gas monitoringGreenhouse gas monitoring is the direct measurement of greenhouse gas emissions and levels. There are several different methods of measuring carbon dioxide concentrations in the atmosphere, including infrared analyzing and manometry. Methane and nitrous oxide are measured by other instruments. Greenhouse gases are measured from space such as by the Orbiting Carbon Observatory and networks of ground stations such as the Integrated Carbon Observation System.
Nitrous-oxide reductaseIn enzymology, a nitrous oxide reductase also known as nitrogen:acceptor oxidoreductase (N2O-forming) is an enzyme that catalyzes the final step in bacterial denitrification, the reduction of nitrous oxide to dinitrogen. N2O + 2 reduced cytochome c N2 + H2O + 2 cytochrome c It plays a critical role in preventing release of a potent greenhouse gas into the atmosphere. N2O is an inorganic metabolite of the prokaryotic cell during denitrification.
Destruction de la couche d'ozoneLa destruction (ou dégradation) de la couche d'ozone est un amincissement voire une disparition de cette couche qui résulte d'un déséquilibre entre la production et la destruction de l’ozone dans la stratosphère. L'épaisseur de la couche d'ozone est mesurée en unité Dobson (DU), 1 DU correspondant à molécules d'ozone par mètre carré. Elle varie autour du globe en fonction de la latitude et des saisons. La couche est mince au niveau de l’équateur (environ 270 DU) et plus épaisse au niveau des pôles (environ 300 DU), elle est plus mince en automne et plus épaisse au printemps.
Greenhouse gas inventoryGreenhouse gas inventories are emission inventories of greenhouse gas emissions that are developed for a variety of reasons. Scientists use inventories of natural and anthropogenic (human-caused) emissions as tools when developing atmospheric models. Policy makers use inventories to develop strategies and policies for emissions reductions and to track the progress of those policies. Regulatory agencies and corporations also rely on inventories to establish compliance records with allowable emission rates.
Rendement chimiqueLe rendement chimique rend compte de l'efficacité de la réaction chimique étudiée. Le rendement désigne le rapport entre la quantité de produit obtenue et la quantité maximale qui serait obtenue si la réaction était totale. Le rendement théorique est la quantité du produit prévue par un calcul stœchiométrique fondée sur les nombres de moles de tout réactif en présence. Ce calcul suppose qu'une seule réaction a lieu et que le réactif limitant réagit complètement.
Composé organiqueLes composés organiques sont les composés dont un des éléments chimiques constitutifs est le carbone, à quelques exceptions près. Ces composés peuvent être d’origine naturelle ou produits par synthèse. Il est utile, au préalable, de distinguer les composés organiques des composés inorganiques. Un composé est une espèce chimique constituée d’au moins deux éléments chimiques différents. L'étymologie du terme « organique » est historique.
Persistent carbeneA persistent carbene (also known as stable carbene) is a type of carbene demonstrating particular stability. The best-known examples and by far largest subgroup are the N-heterocyclic carbenes (NHC) (sometimes called Arduengo carbenes), for example diaminocarbenes with the general formula (R2N)2C:, where the four R moieties are typically alkyl and aryl groups. The groups can be linked to give heterocyclic carbenes, such as those derived from imidazole, imidazoline, thiazole or triazole.
Chemical thermodynamicsChemical thermodynamics is the study of the interrelation of heat and work with chemical reactions or with physical changes of state within the confines of the laws of thermodynamics. Chemical thermodynamics involves not only laboratory measurements of various thermodynamic properties, but also the application of mathematical methods to the study of chemical questions and the spontaneity of processes. The structure of chemical thermodynamics is based on the first two laws of thermodynamics.
Transition metal carbene complexA transition metal carbene complex is an organometallic compound featuring a divalent organic ligand. The divalent organic ligand coordinated to the metal center is called a carbene. Carbene complexes for almost all transition metals have been reported. Many methods for synthesizing them and reactions utilizing them have been reported. The term carbene ligand is a formalism since many are not derived from carbenes and almost none exhibit the reactivity characteristic of carbenes.
Fischer–Speier esterificationFischer esterification or Fischer–Speier esterification is a special type of esterification by refluxing a carboxylic acid and an alcohol in the presence of an acid catalyst. The reaction was first described by Emil Fischer and Arthur Speier in 1895. Most carboxylic acids are suitable for the reaction, but the alcohol should generally be primary or secondary. Tertiary alcohols are prone to elimination. Contrary to common misconception found in organic chemistry textbooks, phenols can also be esterified to give good to near quantitative yield of products.
