Reaction inhibitor

An inhibitor (Latin inhibere, stop ',' pause ') is an inhibitor, ie a substance which one or more reactions - chemical, biological or physical nature - influenced so that they slowed, inhibited or prevented. In particular the term is used in the enzyme kinetics of the enzyme -inhibiting substances, but also in the field of chemistry and technology.

Inhibitors in biochemistry, pharmacology and toxicology

In biochemistry, inhibit or delay inhibitors Enzyme reactions. Depending on the nature of the inhibitor, a distinction in the inhibition of enzymatic reactions shapes.

In essence, these inhibitions are reversible, meaning they can be undone. Irreversible inhibition can be found in the area of poisoning, for example, in cases of poisoning by cyanide.

The reversible inhibition are further divided into:

• Competitive inhibition: Here is competing the inhibitor with the substrate. This can be applied in medicine.
• Allosteric inhibition: This inhibitor alters the molecular structure of the enzyme, so that the substrate can no longer bind.

A special form of competitive inhibition is the product inhibition. In this form of inhibition, the product uses a self-regulating in the enzymatic process. An example is the cholesterol biosynthesis.

Inhibitors in medicine

Inhibitors (inhibitors ) are a serious complication of hemophilia ( hemophilia ). They prevent the efficacy of factor VIII, a protein that is essential for blood clotting. The elimination of the inhibitors is possible by a long-term high dose of factor VIII.

Inhibitors in chemistry

Chemical inhibitors ( passivators, inhibitors, retarders, anti- catalysts negative catalysts) are used for example, to prevent oxidative changes in foods (→ antioxidants ), or the speed of polymerization control. In macromolecular chemistry inhibitors, such as Allen, also used to stop the polymerization and to make statements about the relative concentration of active sites ( places where the polymerization progresses dynamically ). In the processing of gypsum or concrete retarder may be added to prevent the too rapid setting of these building materials. A plaster, in which the retarder is included, is marketed under the trade name ® Moltifill. In catalytic processes inhibitors act as catalyst poisons, such as lead in automotive catalysts.

In the petrochemical industry to the crude oil or natural gas, various inhibitors are added to prevent settling during transport through pipelines to the walls of gas hydrates, which run through the increased pressure drop to a lower flow rate and can clog valves.

Inhibitors in electrochemistry

In electrochemistry inhibitors are used, inter alia, to protect surfaces against corrosion. Here, for example, organic molecules on the surface attach to and block by adsorption reactions with the environment. The corrosion inhibitors, the VCI - means ( Volatile Corrosion Inhibitor ) are widely used as temporary protection. In closed systems, such as cooling systems, the corrosion inhibitors can be added to medium.

Inhibitors in the art

In the HVAC and the water vapor technique inhibitors are added to the water cycle. Thus adverse reactions (for example, corrosion ) is prevented. One of the additives is hydrazine, which binds the present in the water or wet steam oxygen with liberation of nitrogen dioxide. With the addition of hydrazine caused strong alkaline solutions with a pH value of 12 to 13, which provide the necessary safety equipment for alkaline solutions necessary.

Currently, hydrazine is used as a conditioning agent for feed water treatment in power plants. However, the use of high-pressure systems or on systems in the hypercritical region is limited. For operating pressures up to 125 bar substitutes are already being used successfully.

In the food industry, hydrazine may be used only if the permitted limits are not exceeded.

A many lubricants added additive is a so-called corrosion inhibitor whose job it is metallic surfaces such as in motors to protect against corrosion.

Inhibitors in firefighting

In firefighting inhibitors very often used for fire classes B and C in the form of dry powder (heterogeneous inhibition) and now again separated in the form of halons (homogeneous inhibition ) are used.