Bromocyclohexane (also called cyclohexyl bromide, abbreviated CXB) is an organic compound with the

chemical formula In chemistry, a chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, ...

C₆H₁₁Br. It is used to match the

refractive index In optics, the refractive index (or refraction index) of an optical medium is a dimensionless number that gives the indication of the light bending ability of that medium. The refractive index determines how much the path of light is bent, or ...

PMMA PMMA may refer to: * para-Methoxymethamphetamine, a stimulant drug * Philippine Merchant Marine Academy The Philippine Merchant Marine Academy ( fil, Akademiya sa Bapor Pangkalakalan ng Pilipinas) also referred to by its acronym PMMA) is a ma ...

for example in

confocal microscopy Confocal microscopy, most frequently confocal laser scanning microscopy (CLSM) or laser confocal scanning microscopy (LCSM), is an optical imaging technique for increasing optical resolution and contrast of a micrograph by means of using a sp ...

of colloids. A mixture of ''cis''-

decalin Decalin (decahydronaphthalene, also known as bicyclo .4.0ecane and sometimes decaline), a bicyclic organic compound, is an industrial solvent. A colorless liquid with an aromatic odor, it is used as a solvent for many resins or fuel additives. I ...

and CXB can simultaneously match optical index and density of PMMA. Due to the moderate

dielectric constant The relative permittivity (in older texts, dielectric constant) is the permittivity of a material expressed as a ratio with the electric permittivity of a vacuum. A dielectric is an insulating material, and the dielectric constant of an insulat ...

of CXB (ε = 7.9 ), PMMA acquires charges that can be screened by the addition of salt (e.g. tetrabutyl ammonium bromide), leading to a very good approximation of colloidal hard sphere. A drawback is that CXB is a good solvent for PMMA, causing it to swell over time, which may lead to a poor determination of particle radii and determination of solid volume fraction.

Synthesis

Bromocyclohexane can be prepared by the free radical substitution of bromine to the cyclohexane ring at high temperatures or in presence of UV light. The reaction is unselective, giving a mixture of polybrominated products. In principle, another synthesis involves addition of

hydrogen bromide Hydrogen bromide is the inorganic compound with the formula . It is a hydrogen halide consisting of hydrogen and bromine. A colorless gas, it dissolves in water, forming hydrobromic acid, which is saturated at 68.85% HBr by weight at room temper ...

(HBr) to

cyclohexene Cyclohexene is a hydrocarbon with the formula C6H10. This cycloalkene is a colorless liquid with a sharp smell. It is an intermediate in various industrial processes. Cyclohexene is not very stable upon long term storage with exposure to light an ...

References

External links

* {{cite web , url = http://web.pdx.edu/~wamserc/C334F99/Fans.htm , title = Chem 334 - Fall 1999 Organic Chemistry I , author = Dr. Carl C. Wamser , publisher = Portland State University Organobromides