All you need to know about spiro compounds
Introduction to Spiro compounds
A spiro compound is an organic compound in which two bicyclic rings are bonded by a single atom . In nature, the structures of the rings may be substantially the same or different, and the atom connecting the two rings is called spiroatom (spiral atom), usually It is a grade 4 carbon (also known as a spiral carbon), and it can also be silicon , phosphorus , or arsenic . The spiro atom is generally a quaternary carbon atom. The spiro compound will use the parentheses to write the number of rings separately. The ring number also contains the spiro atom itself, and the small number will be in front of the number and separated by a dot.
At least two rings in a molecule share a carbon atom (in other compounds, other atoms, such as silicon, phosphorus, arsenic, etc.). The two rings are located on two planes perpendicular to each other: suitably substituted spiro compounds are chiral and can be resolved into optical isomers (see optical isomerism). In terms of form, propadiene H2C=C=CH2 is the simplest spiro ring, and an appropriately substituted propadiene such as 1,3-propadienediic acid is optically active and can be split into two optically active isomers. body.
Classificatio
(1) According to the number of spiro atoms, the spiro compound can be classified into a single spiro compound, a dispiro, a triple spiro, and a multi-spiral compound containing a plurality of spiro atoms.
(2) The carbocyclic spiro compound and the heterocyclic spiro compound can be classified according to the kind of the atom to be contained, and when the carbon atom constituting the carbocyclic spiro compound is substituted by another atom, a heterocyclic spiro compound is formed.
(3) According to the type of ring, it can be divided into saturated, unsaturated, aromatic and aliphatic spiro compounds.
(4) Coordination heterospirocyclic compounds. The spiro atom in the spiro compound may be a carbon atom or other elements such as Si, N, P, Ge and the like. If the spiro atom is a metal atom, a coordinate bond is generally formed , and such a spiro compound is referred to as a coordinating heterocyclic compound.
Polymeric spiro compound
The polymeric spiro compound is a combination of two or more spiro atoms as three or more rings. When naming a spiro compound, a numerical adjective that adds di-, tri-, tetra-, …, etc. to the name means the number of spiro atoms that exist separately between the rings. The atoms in the spiro compound have been systematically numbered. The terminology of a polyspirocyclic compound begins with a ring molecule that links a spiro atom, which is called a terminal ring. These polyspirocyclic molecules can have two or more terminal rings and are attached to a multi-spirocyclic compound. Among them, only one spiral atom is connected to each other. The nomenclature in the terminal ring is initiated by the atom next to the spiro atom, labeled as the number 1, and the molecule is then numbered starting with the molecule.
Two or more terminal rings, the starting number of the terminal ring will have another selection method. When the first spiroatom is numbered, the subsequent spiro compounds should be connected to the smallest possible spiral. Numbering. Suppose there is a compound with two terminal rings, one with 6 atoms and the other with 8 atoms. The numbering is started with a ring of 6 atoms, because after the numbering, the spiroatom will be numbered 6. If the ring consisting of 8 atoms starts, the spiroatom will be numbered 8. The direction of the number is determined by spiroatom (starting at the first spiroatom of the already numbered terminal ring). Suppose the snail atom starts numbering in one direction, and if the number is less than the number in the other direction, the snail atom is selected. The direction with the smaller number is used to start the naming. In the subsequent spiral atom, the number size of the number is not so important. In some cases, the first two, three, four or more spiroatoms will be programmed to the same number no matter which direction they are numbered. The selection of the numbering direction is selected by the numbering process when a different number of screw atoms is encountered, and the direction of the lower numbered spiral atoms is selected. For example, if the numbering system in one direction, the number of each spiroatom is 3, 5, 7, 10, and the number of spiroatoms in the other direction is 3, 5, 7, 9, then the direction of the second number is selected. . In this case, in the direction of the first number, the number between the two spiral atoms is 7 and 10, and in the opposite number direction, 7 and 9. The numbering of any screw atom after that is not important, and the numbering direction has been determined by the direction of the number 9.
In the naming of multiple spiro rings, the first number in parentheses indicates that the atom in the first ring closest to the spiro atom is the number one. The remaining numbers represent the number of atoms between the spiro atoms, or the atoms in the terminal ring. Each number is separated by a period (English period). In this example, there are two atoms (numbered 1 and 2) before the first spiroatom(3). There are no atoms between 3 and 4 spiroatoms, and the same is true for spiroatoms at 4 and 5, 5 and 6. There are two atoms on the second terminal ring, 6 and 5, 5 and 4, and there is one between 4 and 3.
Therefore, the sequence [2.0.0.0.2.1.1.1] is obtained. In the example on the right, there are two spiroatoms, so the name dispiro starts. In the first terminal ring, there are two atoms, indicating the name dispiro[2. Next, there are one and four atoms in the other terminal ring between the two spiroatoms, revealing the name two snails [2.1.3 5 . The second spiroatom, numbered 5, has been added as a path that will encounter the number of atoms after the number of atoms in the terminal ring, the last time adding 9 and 10 atoms between 3 and 5 spiroatoms And then add an alkane having the same number of atoms of the spiro compound, decane, namedispiro [2.1.3 5 .2 3 ] decane revealed by the name.
General nomenclature of spiro compounds
The monospirocyclic compound determines the name of the parent hydrocarbon according to the total number of carbon atoms involved in the ring formation; the all atoms on the spiro ring are numbered in the order of the small ring and the large ring and the spiro atoms are minimized; then they are followed by square brackets. The numbering sequence of the entire ring is numerically indicated by the number of carbon atoms sandwiched between the respective spiro atoms, plus in front of the name of the chain hydrocarbon corresponding to the entire ring; the numbers are separated by a lower dot, in the form: snail [a , b] an alkane.
Hybrid screw
The anomeric effect of a heterospiral ring means that two electron-positive atoms or lone pairs of electrons in the conformation are in the opposite direction to reduce the dipole moment of the molecule and reduce the intramolecular energy. In 1968, the Descotes research team first proposed an anomeric effect. When they studied the bicyclic acetal, they found that the two compounds in the figure below contained 57% of the cis isomer and 43% of the trans isomer in the equilibrium mixture at 80 C. The cis isomer ratio trans The isomer was stable with an energy difference of 0.71 kJ/mol. Because of the anomeric effect of the cis isomer, the trans isomer has no such effect.
Chirality
Some snail compounds have an axial chirality. Spiroatoms can be chiral centers, even when they lack the four different substituents needed to observe chirality. When the two rings are the same, the CIP system assigns a higher priority to extend the extension of one ring and one other ring of lower priority. It can be applied when the ring is not similar.
Cyclic compounds can be classified by the following criteria:
• Alicyclic compound
• Naphthenic
Cycloolefin
• Aromatic hydrocarbon
The simplest and most important aromatic hydrocarbons are benzeneand its homologues such as toluene , xylene , ethylbenzene and the like. In aromatics, some aromatic rings are not completely benzene structures, but the carbon atoms in them are replaced by nitrogen , oxygen , sulfur and other elements. We call them heterocycles , such as five yuan like furan . The ring includes an oxygen atom and the pyrrole contains a nitrogen atom.Thiophene contains a sulfur atom and the like.
And aromatics can be divided into:
• Polycyclic aromatic hydrocarbon
It consists of an aromatic ring that does not contain a heterocyclic ring or a substituent. Many of them are known or potential carcinogens . The simplest of this chemical is naphthalene , with two aromatic rings, as well as tricyclic compounds ruthenium and phenanthrene .
Polycyclic aromatic hydrocarbons are neutral, non-polar molecules found in coal and tar deposits. They also organic substances by incomplete combustion (e.g., the engine and the incinerator, when forest fires in the biomass combustion, etc.). For example, it is produced by incomplete combustion of carbonaceous fuels such as firewood, wood charcoal, grease, and tobacco. Also found in charred meat .
Polycyclic aromatic compounds above three rings have low solubility and low vapor pressure in water . When the molecular weight increases, both solubility and vapor pressure decrease. The bicyclic polycyclic aromatic compounds have lower solubility and vapor pressure. Polycyclic aromatic compounds are therefore more commonly found in the soil and in sediments than in water and air. However, polycyclic aromatic compounds are often found on suspended particles in the air.
Many polycyclic aromatic compounds have been defined as carcinogens. Clinical trial reports indicate that long-term exposure to high concentrations of polycyclic aromatic compounds can cause skin cancer , lung cancer , stomach cancer and liver cancer . Polycyclic aromatic compounds can destroy genetic material in the body, trigger the growth of cancer cells and increase the incidence of cancer .
When the molecular weight is increased, the carcinogenicity of the polycyclic aromatic compound is also increased, and the acute toxicity is decreased. A polycyclic aromatic compound, Benzo[ a ]pyrene (Benzo[ a ]pyrene), was the first chemical carcinogen to be discovered .
Application
Polymer expansion agent
The volume shrinkage of the polymer during polymerization or solidification is caused by the van der Waals force between the monomer molecules in the liquid state or the uncrosslinked long-chain molecules , and the distance between the molecules is large; after polymerization or crosslinking, Covalent bond distances between structural units only result in shrinkage of the polymer volume. It is mentioned that shrinkage is sometimes fatal to the polymer, such as causing accelerated aging of the polymer, deformation, and decreased overall performance. In order to solve the volume shrinkage problem of polymer curing, chemists have made unremitting efforts, but generally can only reduce and can not completely eliminate volume shrinkage. Until 1972, Bailey et al. developed a series of spiro compounds and found that these compounds are polymerized. When the volume does not shrink, it expands. The discovery of expanded monomers has attracted the interest of many scientists, and a lot of research has been carried out. Expanded monomers have become very active functional polymer materials. Structured compounds such as spiro orthoester and spiro orthocarbonate are good expansion monomers and have been used in the preparation of high strength composites, high performance binders, biodegradable polymer materials and medical polymer materials. Modification of general-purpose polymers and synthesis of oligomers having functional groups .
Electroluminescence
Whether or not an organic compound emits light and the wavelength of light emission and the efficiency of light emission depend mainly on the chemical structure. Fluorescence usually occurs in molecules with rigid planes and conjugated systems , which enhances the electron conjugation effect and the coplanarity of the molecules, which is beneficial to improve the fluorescence efficiency . There are many organic light-dark materials. The main types are: spiro ring, poly-p-phenylene vinylene, polythiophene, polythiadiazole and metal coordination compounds. Among them, spirocyclic aromatic compounds have large conjugated systems and Good rigidity and coplanarity, high glass transition temperature and high thermal stability . The EL device is simple in process and does not require complicated equipment, so it is possible to reduce the manufacturing cost during the period and to easily prepare large-area devices.
pesticide
The fused ring and spiro compound containing hetero atom are not easy to produce resistance due to their unique mechanism of action, and have received extensive attention in the development of pesticides. For example: Rudi et al. reported 3,9-dichloro-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane-3,9-dioxide and sulfide Hydrogen was reacted to synthesize a novel spiro compound, 3,9-dihydro-3,9-dithio-2,4,8,10-tetraoxa-3,9-diphospho[5.5]undecane. Its derivatives are a new class of organophosphate insecticides and herbicides, which can effectively remove mustard, ragweed, etc. from wheat, cereals, cotton and soybeans.