organic chemistry Organic chemistry is a subdiscipline within chemistry involving the science, scientific study of the structure, properties, and reactions of organic compounds and organic materials, i.e., matter in its various forms that contain carbon atoms.Clay ...

, peri-naphthalenes are particular derivatives of

naphthalene Naphthalene is an organic compound with formula . It is the simplest polycyclic aromatic hydrocarbon, and is a white crystalline solid with a characteristic odor that is detectable at concentrations as low as 0.08 ppm by mass. As an aromat ...

with the formula C₁₀H₆-1,8-X₂. Owing to the rigidity of the naphthalene skeleton, these substituents on the 1- and 8-positions are constrained to be relatively close 2.5 Å, which is within the

van der Waals radius The van der Waals radius, ''r'', of an atom is the radius of an imaginary hard sphere representing the distance of closest approach for another atom. It is named after Johannes Diderik van der Waals, winner of the 1910 Nobel Prize in Physics, ...

for many atoms. In contrast, ortho-substituents pendant from a benzene ring are separated by about 3.3 Å.Kilian, P.; Knight, F. R.; Woollins, J. D., "Synthesis of ligands based on naphthalene peri-substituted by Group 15 and 16 elements and their coordination chemistry", Coordination Chemistry Reviews 2011, volume 255, 1387-1413.

Examples

Because of this unusual structural feature, many unusual compounds are derived from peri-naphthalenes. One example is

1,8-bis(dimethylamino)naphthalene 1,8-Bis(dimethylamino)naphthalene is an organic compound with the formula CH(NMe) (Me = methyl). It is classified as a peri-naphthalene, i.e. a 1,8-disubstituted derivative of naphthalene. Owing to its unusual structure, it exhibits exceptional ba ...

, known as proton sponge because of its high affinity for protons. Its ammonium derivative has a pK_a of 12.7. The compound 1,8-bis(dimethylboryl)naphthalene is known as hydride sponge because of its high affinity for hydride. It solubilizes

potassium hydride Potassium hydride, KH, is the inorganic compound of potassium and hydrogen. It is an alkali metal hydride. It is a white solid, although commercial samples appear gray. It is a powerful superbase that is useful in organic synthesis. It is sold c ...

. Other distinctive compounds include the

diphosphine Diphosphane, or diphosphine, is an inorganic compound with the chemical formula P2H4. This colourless liquid is one of several binary phosphorus hydrides. It is the impurity that typically causes samples of phosphine to ignite in air. Propert ...

1,8-bis(diphenylphosphino)naphthalene (dppn) and the disulfide, both of which are ligand precursors.

Synthesis

Several peri-naphthalenes are prepared via

nitration In organic chemistry, nitration is a general class of chemical processes for the introduction of a nitro group into an organic compound. The term also is applied incorrectly to the different process of forming nitrate esters between alcohols an ...

s. Dinitration of naphthalene gives 1,8-dinitronaphthalene, which undergoes hydrogenation to the diamine. The diamine can also be produced by reaction of the 1,8-diol with ammonia at high temperatures. The peri-naphthalene 1-amino-naphthalene-8-sulfonic acid is a precursor to other peri-naphthalenes. It is prepared by nitration of naphthalene-1-sulfonic acid followed by reduction. Diazotization followed by loss of N₂ gives the naphtho

sultone In organosulfur chemistry, a sulfonate is a salt or ester of a sulfonic acid. It contains the functional group , where R is an organic group. Sulfonates are the conjugate bases of sulfonic acids. Sulfonates are generally stable in water, non- ...

. This species reacts with NaOH to give sequentially 1-hydroxynaphthalene-8-sulfonic acid and then the 1,8-diol.. Perinaphthalenes

Certain perinaphthalene derivatives can be prepared from 1,8-dilithionaphthalene, which in turn is generated by dilithiation of

1-bromonaphthalene 1-Bromonaphthalene is an organic compound with the formula C10H7Br. It is one of two isomeric bromonaphthalenes, the other being 2-bromonaphthalene. Under normal conditions, the substance is a colorless liquid. Synthesis and reactions It is pre ...

: :C₁₀H₇Br + BuLi → C₁₀H₇Li + BuBr :C₁₀H₇Li + BuLi → C₁₀H₆Li₂ + BuH The deprotonation requires

tmeda Tetramethylethylenediamine (TMEDA or TEMED) is a chemical compound with the formula (CH3)2NCH2CH2N(CH3)2. This species is derived from ethylenediamine by replacement of the four amine hydrogens with four methyl groups. It is a colorless liquid, ...

References

{{Reflist Naphthalenes