Products are the species formed from chemical reactions.During a chemical reaction reactants are transformed into products after passing through a high energy transition state. This process results in the consumption of the reactants. It can be a spontaneous reaction or mediated by catalysts which lower the energy of the transition state, and by solvents which provide the chemical environment necessary for the reaction to take place. When represented in chemical equations products are by convention drawn on the right-hand side, even in the case of reversible reactions. The properties of products such as their energies help determine several characteristics of a chemical reaction such as whether the reaction is exergonic or endergonic. Additionally the properties of a product can make it easier to extract and purify following a chemical reaction, especially if the product has a different state of matter than the reactants. Reactants are molecular materials used to create chemical reactions. The atoms aren't created or destroyed. The materials are reactive and reactants are rearranging during a chemical reaction. Here is an example of reactants: CH4 + O2. A non-example is CO2 + H2O or "energy".
Much of chemistry research is focused on the synthesis and characterization of beneficial products, as well as the detection and removal of undesirable products. Synthetic chemists can be subdivided into research chemists who design new chemicals and pioneer new methods for synthesizing chemicals, as well as process chemists who scale up chemical production and make it safer, more environmentally sustainable, and more efficient.Other fields include natural product chemists who isolate products created by living organisms and then characterize and study these products.
The products of a chemical reaction influence several aspects of the reaction. If the products are lower in energy than the reactants, then the reaction will give off excess energy making it an exergonic reaction. Such reactions are thermodynamically favorable and tend to happen on their own. If the kinetics of the reaction are high enough, however, then the reaction may occur too slowly to be observed, or not even occur at all. This is the case with the conversion of diamond to lower energy graphite at atmospheric pressure, in such a reaction diamond is considered metastable and will not be observed converting into graphite.
If the products are higher in chemical energy than the reactants then the reaction will require energy to be performed and is therefore an endergonic reaction. Additionally if the product is less stable than a reactant, then Leffler's assumption holds that the transition state will more closely resemble the product than the reactant.Sometimes the product will differ significantly enough from the reactant that it is easily purified following the reaction such as when a product is insoluble and precipitates out of solution while the reactants remained dissolved.
Ever since the mid nineteenth century chemists have been increasingly preoccupied with synthesizing chemical products.Disciplines focused on isolation and characterization of products, such as natural products chemists, remain important to the field, and the combination of their contributions alongside synthetic chemists has resulted in much of the framework through which chemistry is understood today.
Much of synthetic chemistry is concerned with the synthesis of new chemicals as occurs in the design and creation of new drugs, as well as the discovery of new synthetic techniques. Beginning in the early 2000s (decade) though process chemistry began emerging as a distinct field of synthetic chemistry focused on scaling up chemical synthesis to industrial levels, as well as finding ways to make these processes more efficient, safer, and environmentally responsible.
In biochemistry, enzymes act as biological catalysts to convert substrate to product.For example, the products of the enzyme lactase are galactose and glucose, which are produced from the substrate lactose.
Some enzymes display a form of promiscuity where they convert a single substrate into multiple different products. It occurs when the reaction occurs via a high energy transition state that can be resolved into a variety of different chemical products.
Some enzymes are inhibited by the product of their reaction binds to the enzyme and reduces its activity.This can be important in the regulation of metabolism as a form of negative feedback controlling metabolic pathways. Product inhibition is also an important topic in biotechnology, as overcoming this effect can increase the yield of a product.
Catalysis is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst. Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recycles quickly, very small amounts of catalyst often suffice; mixing, surface area, and temperature are important factors in reaction rate. Catalysts generally react with one or more reactants to form intermediates that subsequently give the final reaction product, in the process regenerating the catalyst.
A chemical reaction is a process that leads to the chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the positions of electrons in the forming and breaking of chemical bonds between atoms, with no change to the nuclei, and can often be described by a chemical equation. Nuclear chemistry is a sub-discipline of chemistry that involves the chemical reactions of unstable and radioactive elements where both electronic and nuclear changes can occur.
Muonium is an exotic atom made up of an antimuon and an electron, which was discovered in 1960 by Vernon W. Hughes and is given the chemical symbol Mu. During the muon's 2.2 µs lifetime, muonium can undergo chemical reactions. Due to the mass difference between the antimuon and the electron, muonium is more similar to atomic hydrogen than positronium. Its Bohr radius and ionization energy are within 0.5% of hydrogen, deuterium, and tritium, and thus it can usefully be considered as an exotic light isotope of hydrogen.
A coordinate covalent bond, also known as a dative bond, dipolar bond, or coordinate bond is a kind of two-center, two-electron covalent bond in which the two electrons derive from the same atom. The bonding of metal ions to ligands involves this kind of interaction. This type of interaction is central to Lewis theory.
A reagent is a substance or compound added to a system to cause a chemical reaction, or added to test if a reaction occurs. The terms reactant and reagent are often used interchangeably—however, a reactant is more specifically a substance consumed in the course of a chemical reaction. Solvents, though involved in the reaction mechanism, are usually not called reactants. Similarly, catalysts are not consumed by the reaction, so they are not reactants. In biochemistry, especially in connection with enzyme-catalyzed reactions, the reactants are commonly called substrates.
The Grignard reaction is an organometallic chemical reaction in which alkyl, allyl, vinyl, or aryl-magnesium halides is added to a carbonyl group in an aldehyde or ketone. This reaction is important for the formation of carbon–carbon bonds. The reaction of an organic halide with magnesium is not a Grignard reaction, but provides a Grignard reagent.
An exothermic reaction is a "reaction for which the overall standard enthalpy change ΔH⚬ is negative." Exothermic reactions usually release heat and entail the replacement of weak bonds with stronger ones. The term is often confused with exergonic reaction, which IUPAC defines as "... a reaction for which the overall standard Gibbs energy change ΔG⚬ is negative." A strongly exothermic reaction will usually also be exergonic because ΔH⚬ makes a major contribution to ΔG⚬. Most of the spectacular chemical reactions that are demonstrated in classrooms are exothermic and exergonic. The opposite is an endothermic reaction, which usually takes up heat and is driven by an entropy increase in the system.
In chemistry an activated complex is defined by the International Union of Pure and Applied Chemistry (IUPAC) as "that assembly of atoms which corresponds to an arbitrary infinitesimally small region at or near the col of a potential energy surface". In other words, it refers to a collection of intermediate structures in a chemical reaction that persist while bonds are breaking and new bonds are forming. It therefore represents not one defined state, but rather a range of transient configurations that a collection of atoms passes through in between clearly defined products and reactants.
An exergonic process is one which there is a positive flow of energy from the system to the surroundings. This is in contrast with an endergonic process. Constant pressure, constant temperature reactions are exergonic if and only if the Gibbs free energy change is negative (∆G < 0). "Exergonic" means "releasing energy in the form of work". In thermodynamics, work is defined as the energy moving from the system to the surroundings during a given process.
A cycloaddition is a chemical reaction, in which "two or more unsaturated molecules combine with the formation of a cyclic adduct in which there is a net reduction of the bond multiplicity." The resulting reaction is a cyclization reaction. Many but not all cycloadditions are concerted and thus pericyclic. Nonconcerted cycloadditions are not pericyclic. As a class of addition reaction, cycloadditions permit carbon–carbon bond formation without the use of a nucleophile or electrophile.
In chemistry, homogeneous catalysis is catalysis in a solution by a soluble catalyst. Homogeneous catalysis refers to reactions where the catalyst is in the same phase as the reactants, principally in solution. In contrast, heterogeneous catalysis describes processes where the catalysts and substrate are in distinct phases, typically solid-gas, respectively. The term is used almost exclusively to describe solutions and implies catalysis by organometallic compounds. Homogeneous catalysis is established technology that continues to evolve. An illustrative major application is the production of acetic acid. Enzymes are examples of homogeneous catalysts.
In chemistry, yield, also referred to as reaction yield, is a measure of the quantity of moles of a product formed in relation to the reactant consumed, obtained in a chemical reaction, usually expressed as a percentage. Yield is one of the primary factors that scientists must consider in organic and inorganic chemical synthesis processes. In chemical reaction engineering, "yield", "conversion" and "selectivity" are terms used to describe ratios of how much of a reactant was consumed (conversion), how much desired product was formed (yield) in relation to the undesired product (selectivity), represented as X, Y, and S.
In chemistry, homolysis or homolytic fission is chemical bond dissociation of a molecular bond by a process where each of the fragments retains one of the originally bonded electrons. During homolytic fission of a neutral molecule with an even number of electrons, two free radicals will be generated. That is, the two electrons involved in the original bond are distributed between the two fragment species. The energy involved in this process is called bond dissociation energy (BDE). Bond cleavage is also possible by a process called heterolysis.
A potential energy surface (PES) describes the energy of a system, especially a collection of atoms, in terms of certain parameters, normally the positions of the atoms. The surface might define the energy as a function of one or more coordinates; if there is only one coordinate, the surface is called a potential energy curve or energy profile. An example is the Morse/Long-range potential.
Oxidative coupling in chemistry is a coupling reaction of two molecular entities through an oxidative process. Usually oxidative couplings are catalysed by a transition metal complex like in classical cross-coupling reactions, although the underlying mechanism is different due to the oxidation process that requires an external oxidant. Many such couplings utilize dioxygen as the stoichiometric oxidant but proceed by electron transfer.
Gas phase ion chemistry is a field of science encompassed within both chemistry and physics. It is the science that studies ions and molecules in the gas phase, most often enabled by some form of mass spectrometry. By far the most important applications for this science is in studying the thermodynamics and kinetics of reactions. For example, one application is in studying the thermodynamics of the solvation of ions. Ions with small solvation spheres of 1, 2, 3... solvent molecules can be studied in the gas phase and then extrapolated to bulk solution.
A dispersion is a system in which distributed particles of one material are dispersed in a continuous phase of another material. The two phases may be in the same or different states of matter.
The photostationary state of a reversible photochemical reaction is the equilibrium chemical composition under a specific kind of electromagnetic irradiation. It is a property of particular importance in photochromic compounds, often used as a measure of their practical efficiency and usually quoted as a ratio or percentage. The position of the photostationary state is primarily a function of the irradiation parameters, the absorbance spectra of the chemical species, and the quantum yields of the reactions. The photostationary state can be very different from the composition of a mixture at thermodynamic equilibrium. As a consequence, photochemistry can be used to produce compositions that are "contra-thermodynamic." For instance, although cis-stilbene is "uphill" from trans-stilbene in a thermodynamic sense, irradiation of trans-stilbene results in a mixture that is predominantly the cis isomer. As an extreme example, irradiation of benzene at 237 to 254 nm results in formation of benzvalene, an isomer of benzene that is 71 kcal/mol higher in energy than benzene itself.
In chemistry, chemical stability is the thermodynamic stability of a chemical system.
Phase separation is the creation of two distinct phases from a single homogeneous mixture. The most common type of phase separation is between two immiscible liquids such as oil and water. Colloids are formed by phase separation, though not all phase separation forms colloids - for example oil and water can form separated layers under gravity rather than remaining as microscopic droplets in suspension.