Meso compounds are achiral compounds with chiral centers. Although it includes two or more stereocenters, it is overlaid on its mirror counterpart and is optically inactive. A chiral molecule can adopt two different enantiomeric forms, which are called enantiomers. The term "meso" comes from the Greek mētron, meaning "middle," because these molecules have asymmetric carbon atoms that lie in the middle of chemical structures rather than at one end like amino acids or sugars.
Meso products arise when the reaction of two identical monomers produces a compound that contains no stereocenters. Because the reaction proceeds with complete symmetry, all possible diastereomers will be produced in equal amounts. If the reaction conditions are suitable, the diastereomers will separate out of solution to give a mixture of meso products.
A meso compound, also known as a meso isomer, is a non-optically active member of a group of stereoisomers that includes at least two optically active isomers. This signifies that the molecule is not chiral, despite the presence of two or more stereogenic centers. Because it's a racemic mixture, it displays no optical activity in either its pure form or when dissolved in a suitable solvent.
Meso compounds may be produced by randomizing the orientation of some or all of the asymmetric carbon atoms present in an enantiomorphic pair. Thus, both members of an enantiomorphic pair of diastereomers will be represented in equal amounts in a sample of the meso compound; whereas one diastereomer will be found in greater abundance than its counterpart if the original pair was chiral. For example, consider the case of a lysergic acid diethylamide (LSD) molecule. There are four possible configurations or "stereocenters" in this molecule: two tertiary and two quaternary. If we imagine rotating each of these around their respective axes, we would end up with 24 different stereoisomers. However, since LSD is a meso compound, they would appear as equal amounts in a sample of the substance. One might wonder why nature makes no attempt to produce meso compounds. The reason is that they are generally less stable than their optically active counterparts.
A meso compound, also known as a meso isomer, is a non-optically active member of a collection of stereoisomers that includes at least two optically active isomers. Meso compounds lack optical activity due to the presence of a plane of symmetry, which cancels out optical activity. Because they are non-active, all meso compounds are colorless or white, depending on the specific composition of the molecule. The term "meso" comes from the Greek word meaning equal. As there is an equal number of atoms of each type in a meso compound, these molecules can't display any preference for either right- or left-handed orientations when placed inside our body or outside it.
Meso compounds include many natural products and pharmaceutical drugs. For example, cellulose is a meso polymer, as are amylopectin, chitin, and heparin. In addition, the antimalarial drug quinine is also a meso compound. Although most meso compounds are natural products, some are not; for example, Eero Koskinen has developed a method for making meso compounds by chemical synthesis.
Meso compounds have several important applications in chemistry. For example, cellulose is used as a fiber material in clothing, paper, and other consumer products because it's very strong yet flexible.
Meso compounds come in a variety of forms, including pentane, butane, heptane, and even cyclobutane. They do not have to be two stereocenters, but they can be more. A meso compound has equal numbers of carbon atoms with double bonds to each other (all-trans). It does not mean that the compound itself is all trans, just that there are an equal number of carbon-carbon double bonds in each direction about the molecule.
An example of a meso compound is 1,1'-binaphthyl (BINAP). BINAP has an even number of carbon atoms, and so it is meso. It also has an equal number of carbon-carbon double bonds in each direction about the molecule (all trans). BINAP can be made by heating 1,8-dihydroxynaphthalene in a mixture of sulfuric acid and chlorosulfuric acid.
Another example of a meso compound is phytyl alcohol (phytol). Phytol has an odd number of carbon atoms, and so it is meso. Phytol can be made by oxidizing soybean oil with performic acid.
Organic substances are described by the words "achiral" and "meso." The primary distinction between "achiral" and "meso" compounds is that achiral compounds lack chiral centers, whereas meso compounds have many chiral centers. In conclusion, an achiral compound is the inverse of a chiral chemical. For example, myristic acid is achiral while stearic acid is chiral.
Meso compounds can be classified as right- or left-handed depending on the arrangement of their chiral centers. For example, R-(+)-mandelonitrile is called a right-handed molecule because its carbon chain is aligned with its ring system (a cyclic system). In contrast, S-(-)-mandelonitrile is called a left-handed molecule because its carbon chain is crossed over relative to the ring system (a linear system).
Many drugs are achiral molecules but they often bind to proteins that have a strong preference for one chirality over the other. For example, insulin is used to treat diabetes; however, it binds to receptors on cells that contain both R- and S-type glucose transporters. This causes insulin to activate both types of transporters, resulting in increased uptake of glucose into these cells.
The opposite of achiral is meso.
If A is a meso complex, it must have two or more stereocenters, an internal plane, and R and S stereochemistry.
A racemic mixture comprises enantiomers in equimolar proportions. Because of external compensation, it is optically inactive. It has the ability to be resolved into optically active forms. Because of internal correction, a meso compound is optically inactive. It cannot be resolved into optical forms.
Meso compounds can occur as chiral centers are present in their structures. If there are two different groups attached to the central carbon atom, the molecule will have two possible configurations (R or S). For example, if there is an OH group on one side of the carbon and a CH3 group on the other, the molecule can be arranged so that the OH is on the same side as the CH3 or on the opposite side. These two arrangements or stereoisomers are called enantiomers. A racemic mixture of such a compound contains equal amounts of each enantiomer. Because they are not separated from each other, they remain in equilibrium with one another and cannot be resolved into pure enantiomers.
Meso compounds can also be considered as chiral centers are present in their structures. If there are two different groups attached to the central carbon atom, the molecule will have four possible configurations (RR, SS, RS, and SR). As we know, molecules only exist in single spatial arrangements or stereoisomers. A racemic mixture of such a compound contains equal amounts of each of its four possible stereoisomers.