CYCLOHEXANE

CAS NO: 110-82-7
EC Number:203-806-2

Cyclohexane is a cycloalkane with the molecular formula C6H12. Cyclohexane is non-polar. 
Cyclohexane is a colorless, flammable liquid with a distinctive detergent-like odor, reminiscent of cleaning products (in which it is sometimes used). 
Cyclohexane is mainly used for the industrial production of adipic acid and caprolactam, which are precursors to nylon.
Cyclohexyl (C6H11) is the alkyl substituent of cyclohexane and is abbreviated Cy.
Cyclohexane appears as a clear colorless liquid with a petroleum-like odor. 
Used to make nylon, as a solvent, paint remover, and to make other chemicals. 
Flash point -4°F.
Density 6.5 lb / gal (less than water) and insoluble in water. 
Vapors heavier than air.

Production
Modern production
On an industrial scale, cyclohexane is produced by hydrogenation of benzene in the presence of a Raney nickel catalyst. 
Producers of cyclohexane account for approximately 11.4% of the global demand for benzene. 
The reaction is highly exothermic, with ΔH(500 K) = -216.37 kJ/mol). 
Dehydrogenation commenced noticeably above 300°C, reflecting the favorable entropy for dehydrogenation.

Historical methods
Unlike benzene, cyclohexane is not found in natural resources such as coal. 
For this reason, early investigators synthesized their cyclohexane samples.

Reactions and uses
Although rather unreactive, cyclohexane undergoes catalytic oxidation to produce cyclohexanone and cyclohexanol. 
The cyclohexanone–cyclohexanol mixture, called "KA oil", is a raw material for adipic acid and caprolactam, precursors to nylon. Several million kilograms of cyclohexanone and cyclohexanol are produced annually.

Laboratory solvent and other niche uses
Cyclohexane is used as a solvent in some brands of correction fluid. 
Cyclohexane is sometimes used as a non-polar organic solvent, although n-hexane is more widely used for this purpose. 
Cyclohexane is frequently used as a recrystallization solvent, as many organic compounds exhibit good solubility in hot cyclohexane and poor solubility at low temperatures.

Cyclohexane is also used for calibration of differential scanning calorimetry (DSC) instruments, because of a convenient crystal-crystal transition at −87.1 °C.

Cyclohexane vapor is used in vacuum carburizing furnaces, in heat treating equipment manufacture.

Conformation
Main article: Cyclohexane conformation
The 6-vertex edge ring does not conform to the shape of a perfect hexagon. 
The conformation of a flat 2D planar hexagon has considerable angle strain because its bonds are not 109.5 degrees, the torsional strain would also be considered because all of the bonds would be eclipsed bonds. 
Therefore, to reduce torsional strain, cyclohexane adopts a three-dimensional structure known as the chair conformation, which rapidly interconvert at room temperature via a process known as a chair flip. 
During the chair flip, there are three other intermediate conformations that are encountered: the half-chair, which is the most unstable conformation, the more stable boat conformation, and the twist-boat, which is more stable than the boat but still much less stable than the chair. 
The chair and twist-boat are energy minima and are therefore conformers, while the half-chair and the boat are transition states and represent energy maxima. 
The idea that the chair conformation is the most stable structure for cyclohexane was first proposed as early as 1890 by Hermann Sachse, but only gained widespread acceptance much later. 
The new conformation puts the carbons at an angle of 109.5°. 
Half of the hydrogens are in the plane of the ring (equatorial) while the other half are perpendicular to the plane (axial). This conformation allows for the most stable structure of cyclohexane. 
Another conformation of cyclohexane exists, known as boat conformation, but it interconverts to the slightly more stable chair formation. 
If cyclohexane is mono-substituted with a large substituent, then the substituent will most likely be found attached in an equatorial position, as this is the slightly more stable conformation.

Cyclohexane has the lowest angle and torsional strain of all the cycloalkanes, as a result, cyclohexane has been deemed a 0 in total ring strain.

IDENTIFICATION
Cyclohexane is a colorless liquid. 
Cyclohexane has a pungent, petroleum-like odor. 
Cyclohexane is slightly soluble in water. 

A gas chromatographic system was used to quantitate more than 300 gas-phase cmpd, as hydrocarbons, from roadside ambient air samples. 
Samples were simultaneously collected in Tedlar bags and on Tenax cartridges. 
Hydrocarbons from Tedlar bag collected samples were quantitated on a gas chromatograph arranged in a dual column configuration and equipped with a flame ionization detector. 
The C2 and C3 hydrocarbons were separated on a 5 m long stainless steel column packed with silica gel. 
C4 to C13 hydrocarbons were separated on a 125 m long glass capillary column containing 7.5% hydrophobic silica. 
A stainless steel subambient hydrocarbon trap filled with untreated glass wool permitted the concn of at least 4 L of sample at 70% relative humidity. 
A temperature controller cooled the trap for hydrocarbon concn and thermally described the hydrocarbons for gas chromatographic analysis. 
This trap extends the detection limits for most hydrocarbons to 15.0 ppt carbon. 
Hydrocarbons collected on Tenax cartridges were analyzed by gas chromatography/mass spectrometry in order to provide qualitative identification for the peaks obtained from the GC analysis.

USES:
Over 98% of the cyclohexane produced is used to make nylon intermediates. 
Cyclohexane is used as a solvent for lacquers, resins and synthetic rubber. 
Cyclohexane can also be used as paint and varnish remover. 
Cyclohexane is present in all crude oils. 
Cyclohexane can be released in volcanic emissions, tobacco smoke and plant volatiles. 
Over 98% of the cyclohexane produced is used to make nylon intermediates, adipic acid (60%), caprolactam, and hexamethylenediamine 75% of the caprolactam produced worldwide is used for nylon 6 manufacture. 
Minor miscellaneous uses, such as solvents and polymer reaction diluents, consume the remainder of the cyclohexane produced.
Organic solvent for lacquers and resins. 
Paint and varnish remover. 
In the extraction of essential oils. 
In analytical chemistry for molecular weight determinations (cryoscopic constant 20.3). 
In the manufacturing of adipic acid, benzene, cyclohexyl chloride, nitrocyclohexane, cyclohexanol and cyclohexanone. 
In the manufacturing of solid fuel for camp stoves. 
In fungicidal formulations (possesses slight fungicidal action), In the industrial recrystallization of steroids.

EXPOSURE
People that work in industries where products containing cyclohexane are used will have the highest exposure. 
Nylon industry workers are the most likely to be exposed. 
Other industries could include shoe and leather factories, printing plants, and furniture and mechanical industries. 
The general population may be exposed to cyclohexane from tobacco smoke, gasoline fumes or smog. 
Cyclohexane can be found at low levels in surface, ground and drinking waters. 
Cyclohexane can also be found in air. Cyclohexane breaks down in air by reaction with other chemicals. 
Cyclohexane is expected to rapidly evaporate from soil and water surfaces. 
Cyclohexane that remains in soil or water may be slowly broken down by microorganisms. 
Cyclohexane is expected to build up in aquatic organisms. 

INDUSTRY USE
-Adhesives and sealant chemicals
-Agricultural chemicals (non-pesticidal)
-Corrosion inhibitors and anti-scaling agents
-Fuels and fuel additives
-Functional fluids (closed systems)
-Intermediates
-Laboratory chemicals
-Lubricants and lubricant additives
-Paint additives and coating additives not described by other categories
-Polymer manufacturing
-Processing aids, not otherwise listed
-Solvents (which become part of product formulation or mixture)

CONSUMER USE
-Adhesives and sealants
-Agricultural products (non-pesticidal)
-Building/construction materials not covered elsewhere
-Fuels and related products
-Ink, toner, and colorant products
-Lubricants and greases
-Paints and coatings
-Petrochemicals
-college and university laboratory research, other chemical preparation, laboratory use
-Pharmaceutical prep and laboratory use.
Methods of Manufacturing
Benzene can be hydrogenated catalytically to cyclohexane in either the liquid or the vapour phase in the presence of hydrogen. 
Several cyclohexane processes, which use nickel, platinum, or palladium as the catalyst, have been developed. 
Usually, the catalyst is supported, e.g., on alumina, but at least one commercial process utilizes Raney nickel.
Occurs in petroleum (0.5-1.0%). 
Obtained in the distillation of petroleum ... 
In the distillation of petroleum, the C4-400 °F boiling range naphthas are fractionated to obtain C5-200 °F naphtha containing 10-14% cyclohexane which on superfractionation yields an 85% concentrate (which is sold as such), further purification /of 85% concentrate cyclohexane/ necessitates isomerization of pentanes to cyclohexane, heat cracking for removing open-chain hydrocarbons and sulfuric acid treatment to remove aromatic compounds.

Industry Processing Sectors
-Adhesive manufacturing
-All other basic organic chemical manufacturing
-All other chemical product and preparation manufacturing
-Asphalt paving, roofing, and coating materials manufacturing
-Computer and electronic product manufacturing
-Food, beverage, and tobacco product manufacturing
-Miscellaneous manufacturing
-Oil and gas drilling, extraction, and support activities
-Paint and coating manufacturing
-Petrochemical manufacturing
-Petroleum lubricating oil and grease manufacturing
-Petroleum refineries
-Pharmaceutical and medicine manufacturing
-Plastic material and resin manufacturing
-Printing ink manufacturing
-Rubber product manufacturing
-Services
-Spent liquid for Polymer manufacturing
-Transportation equipment manufacturing
-University or college research
-Wholesale and retail trade

How is it produced?
Industrial cyclohexane can be produced by two methods.  
The first is the catalytic hydrogenation of benzene using rhodium on carbon, and the second method is via fractional distillation of petroleum.

How is it stored and distributed?
Cyclohexane has a specific gravity of 0.78 and a flashpoint of -20° C and is highly flammable.  
Cyclohexane should be stored in a cool, dry, and well-ventilated area which is free from the risk of ignition.  
For transportation purposes, it is classified as hazard class 3 and packing group II and is should be labelled as an irritant.

What Cyclohexane used for?
Cyclohexane is used predominately in the nylon industry where approximately 90% of it is consumed in the industrial production of adipic acid and caprolactam, which are themselves used to generate nylon6 and nylon6.6.  
The remaining 10% is used both as a solvent for paints, resins, varnish and oil, and as a plasticiser.  
Cyclohexane can also be used as an intermediate in the manufacture of other industrial chemicals such as cyclohexanone and nitrocyclohexanone.

Cyclohexane is generally used as an intermediate chemical. 
Specifically, 54% of what is produced is used in the production of adipic acid for nylon-6/6, 39% for caprolactam for nylon-6, and 7% for products including solvents, insecticides and plasticizers. 
The demand for nylon (and hence cyclohexane) in engineering thermoplastics in resins and films is growing at about 6% annually. 
Engineering thermoplastics are noted for their outstanding properties of high tensile strength, excellent abrasion, and chemical resistance and heat resistance. 

All cyclohexane is produced in benzene hydrogenation units. 
In the process, high-purity benzene feed and purified hydrogen (typically recovered from reformers and ethylene crackers) are brought to reaction temperatures and charged to the reactor. 
The conversion of benzene to cyclohexane is stoichiometric and almost complete, finished cyclohexane typically contains less than 50 ppm of benzene. 
A small amount of lower purity cyclohexane is recovered from petroleum streams by fractionation and extraction.

Over 90% of the cyclohexane production is used to produce intermediates for nylon 6 and nylon 6,6. 
Nylon 6 is made by polymerizing caprolactam which is derived from the nitration of cyclohexane. 
Nylon 6,6 is made by polymerizing equal molar quantities of adipic acid and hexamethylene diamine (HMDA). 
Adipic acid is made by a two-step air and nitric acid oxidation of cyclohexane. 
The adipic acid is converted to HMDA by the reduction of adiponitrile (an intermediate). 
Adipic acid produced from cyclohexane is also used to manufacture esters for plasticizers and synthetic lubricants, as well as produce polyurethanes (synthetic leather).

Most cyclohexane goes into the production of intermediates for nylon, which has a variety of common applications such as clothing, tents and carpets as well as thermoplastics. 
Cyclohexane is also used as a solvent in chemical and industrial processes and recently has been substituted for benzene in many applications. 

Cyclohexane derivatives

The specific arrangement of functional groups in cyclohexane derivatives, and indeed in most cycloalkane molecules, is extremely important in chemical reactions, especially reactions involving nucleophiles. 
Substituents on the ring must be in the axial formation to react with other molecules. 
For example, the reaction of bromocyclohexane and a common nucleophile, a hydroxide anion , would result in cyclohexene.

This reaction, commonly known as an elimination reaction or dehalogenation (specifically E2), requires that the bromine substituent be in the axial formation, opposing another axial H atom to react. 
Assuming that the bromocyclohexane was in the appropriate formation to react, the E2 reaction would commence as such:

1-The electron pair bond between the C-Br moves to the Br, forming Br− and setting it free from cyclohexane 
2-The nucleophile (-OH) gives an electron pair to the adjacent axial H, setting H free and bonding to it to create H2O 
3-The electron pair bond between the adjacent axial H moves to the bond between the two C-C making it C=C 
Note:All three steps happen simultaneously, characteristic of all E2 reactions.

The reaction above will generate mostly E2 reactions and as a result the product will be mostly (~70%) cyclohexene. 
However, the percentage varies with conditions, and generally, two different reactions (E2 and Sn2) compete. 
In the above reaction, an Sn2 reaction would substitute the bromine for a hydroxyl (OH-) group instead, but once again, the Br must be in axial to react. 
Once the SN2 substitution is complete, the newly substituted OH group would flip back to the more stable equatorial position quickly (~1 millisecond).

Cyclohexane is a volatile solvent used as a harmless substitute for dangerous organic solvents in several products, such as paint thinners, gasoline and adhesives.  

Nearly all cyclohexane is used to make cyclohexanol and cyclohexanone, which, in turn, are used mainly as precursors for the production of adipic acid and caprolactam, respectively. 
Other uses for cyclohexane include various solvent applications and the production of cyclohexanol and cyclohexanone for nonprecursor use. 
As a result of cyclohexane’s intrinsic link to the polyamide chain and its use in automobiles, construction, and textiles, global cyclohexane demand remains strongly influenced by macroeconomic conditions. 
Cyclohexane is consumed largely for nylon 6 fibres, resins, and films.

Cyclohexane is produced commercially by the hydrogenation of benzene and by the fractionation and purification of hydrocarbon streams. 
There are both liquid- and vapour-phase process technologies for cyclohexane production. 
Hydrogenation of benzene is the predominant method, accounting for 100% of world cyclohexane capacity. 
Since highpurity cyclohexane is required for caprolactam and most adipic acid production, the higher-purity benzene-derived material is far more important commercially. 
Purity is a function of benzene and hydrogen feed and can be as high as 99.99% with some commercial processes.

Cyclohexane is mainly used in the manufacture of cyclohexanol and cyclohexanone. 
Cyclohexane is widely used as a solvent in the paint industry. 
Cyclohexane is also used as a solvent in organic synthesis, extraction solvent, pigment diluent. 
Most cyclohexane is used to make adipic acid, caprolactam and hexamethylene diamine (98% of total consumption), a small part is used to make cyclohexylamine and other aspects, such as fibre ethers, fats, wax, asphalt, resin and rubber solvent; organic and recrystallization media, paint and varnish remover, etc. 
Cyclohexane can be used as a raw material for nylon 6 and nylon 66. 
Cyclohexane can also be used as a polymerization diluent, paint remover, detergent, adipic acid extractant and binder.

Uses:
Solvent for lacquers and resins. Paint and varnish remover. 
In the extraction of essential oils. In analytical chemistry for mol wt determinations (cryoscopic constant 20.3).
In the manufacture of adipic acid, benzene, cyclohexyl chloride, nitrocyclohexane, cyclohexanol and cyclohexanone. 
In the manufacture of solid fuel for camp stoves. 
In fungicidal formulations (possesses slight fungicidal action). 
In the industrial recrystallization of steroids.
Colorless liquid with a sweet, chloroform-like odour. 
A detection odor threshold concentration of 2,700 mg/m3 (784 ppmv) was experimentally determined by Dravnieks (1974). 
An odor threshold concentration of 2.7 ppbv was reported by Nagata and Takeuchi (1990).
Cyclohexane is a petroleum product obtained by distilling C4- 400°F boiling range naphtha, followed by fractionation and superfractionation, also formed by catalytic hydrogenation of benzene. 
Cyclohexane is used extensively as a solvent for lacquers and resins, as a paint and varnish remover, and in the manufacture of adipic acid, benzene, cyclohexanol, and cyclohexanone.
Commercially most of cyclohexane produced is converted into cyclohexanone-cyclohexanol mixture (or "KA oil") by catalytic oxidation. 
KA oil is then used as a raw material for adipic acid and caprolactam. 
Practically, if the cyclohexanol content of KA oil is higher than cyclohexanone, it is more likely(economical) to be converted into adipic acid, and the reverse case, caprolactam production is more likely. 
Such ratio in KA oil can be controlled by selecting suitable oxidation catalyts. 
Some of cyclohexane is used as an organic solvent.
Cyclohexane often is used by the industrial industry. 
For example, almost 90% of cyclohexane is used in making nylon fiber and nylon molding resin and the rest of it is used in solvents for paint, resins, and plasticizers. 
Also cyclohexane is used as an organic solvent. 
Cyclohexane is a component of petroleum.

To produce commercially, cyclohexane has to convert into cyclohexanone-cyclohexanol mixture. 
Cyclohexane can be used for calibration of differential scanning calorimetry instruments and surface combustion. (heat treating equipment)

Reactivity Profile
Liquid nitrogen dioxide was fed into a nitration column containing hot Cyclohexane, due to an error. 

Purification Methods
Cyclohexane is best to purify it by washing with conc H2SO4 until the washings are colourless, followed by water, aqueous Na2CO3 or 5% NaOH, and again water until neutral. 
Cyclohexane is then dried with P2O5, Linde type 4A molecular sieves, CaCl2, or MgSO4 then Na and distilled. 
Cyclohexane has been refluxed with and distilled from Na, CaH2, LiAlH4 (which also removes peroxides), sodium/potassium alloy, or P2O5. 
Traces of *benzene can be removed by passage through a column of silica gel that has been freshly heated: this gives material suitable for ultraviolet and infrared spectroscopy. 
If there is much *benzene in the cyclohexane, most of it can be removed by a preliminary treatment with nitrating acid (a cold mixture of 30mL conc HNO3 and 70mL of conc H2SO4) which converts *benzene into nitrobenzene. 
The impure cyclohexane and the nitrating acid are placed in an ice bath and stirred vigorously for 15minutes, after which the mixture is allowed to warm to 25o during 1hour. 
The cyclohexane is decanted, washed several times with 25% NaOH, then water, dried with CaCl2, and distilled from sodium. Carbonyl-containing impurities can be removed as described for chloroform. 
Other purification procedures include passage through columns of activated alumina and repeated crystallisation by partial freezing. 
Small quantities may be purified by chromatography on a Dowex 710-Chromosorb W gas-liquid chromatographic column. 
Flammable liquid. 

Rapid purification: 
Distil, discarding the forerun. Stand distillate over Grade I alumina (5% w/v) or 4A molecular sieves.

General Description
A clear colourless liquid with a petroleum-like odour. 
Used to make nylon, as a solvent, paint remover, and to make other chemicals. 
Flashpoint -4°F. 
Density 6.5 lb/gal (less than water) and insoluble in water. 
Vapours heavier than air.

Chemical Properties
colorless liquid

Cyclohexane is an acyclic hydrocarbon from the Cycloalkane family. 
Cyclohexane is used as a non polar solvent in the chemical industry and a reactant in industrial production of Adipic acid and caprolactam, intermediates in Nylon production. 
Pure cyclohexane is non-reactive and is typically only used as a solvent. 
The oxidation of cyclohexane provides cyclohexanol and cyclohexanone. 
They are much more reactive and are used among others as a raw material for the production of adipic acid and caprolactam.

Cyclohexane is mainly used for the industrial production of adipic acid and caprolactam, which are precursors to nylon. 
Cyclohexane is a colourless, flammable liquid with a distinctive detergent-like odor, reminiscent of cleaning products (in which it is sometimes used).

Description
Cyclohexane is a cycloalkane with the molecular formula C6H12. 
Cyclohexane is a colourless, flammable liquid with a distinctive detergent-like odor, reminiscent of cleaning products (in which it is sometimes used).

Uses:
Cyclohexane, for HPLC 99.8% Cas 110-82-7 - used as a recrystallization solvent, as many organic compounds exhibit good solubility in hot cyclohexane and poor solubility at low temperatures.

Production Methods
Cyclohexane is fractionated from crude oil and may be released wherever petroleum products are refined, stored, and used. Another large source of general release is in exhaust gases from motor vehicles. 
Cyclohexane is prepared synthetically from benzene, by hydrocracking of cyclopentane, or from toluene by simultaneous dealkylation and double bond hydrogenation.

Cyclohexane is a cycloalkane with the molecular formula C6H12. 
Cyclohexane is used as a nonpolar solvent for the chemical industry, and also as a raw material for the industrial production of adipic acid and caprolactam, both of which are intermediates used in the production of nylon. 
On an industrial scale, cyclohexane is produced by reacting benzene with hydrogen. 
Due to its unique chemical and conformational properties, cyclohexane is also used in labs in analysis and as a standard.

Properties
Cyclohexane is a compound composed of carbon and hydrogen. 
Cyclohexane is a clear and volatile liquid type of organic compound. Its odor is a faint ether-like. 
Its molecular formula is C6H12 and has a molecular weight of 84.18. Its boiling point is 80.7C and melting point is 6.47C. 
Its vapor density is 2.90, vapor pressure is 97.6 mm Hg at 25 oC ,and flash point is -18 C. 
Cyclohexane's molecular shape is a hexagon. 

The carbon atom in cyclohexane are in a hexagonal shape, having a carbon to carbon bonds on both sides and two hydrogen bonds in each of the carbon. 
The electronegativity of carbon and hydrogen are about equal therefore making it a nonpolar covalent bonded molecule. 
Cyclohexane is insoluble in water because of its structure and its bond, making it hydrophobic. 
Cyclohexane can be broken down by alcohol, ether, acetone, benzene, and ligroin.

IUPAC Names: 
cyclehexane
cyclohaxane
Cyclohexan
Cyclohexan
CYCLOHEXANE
Cyclohexane
Hexahydrobenzene
Hexamethylene
Naphthene

SYNONYMS:
CYCLOHEXANE;
110-82-7;
Hexamethylene;
Hexahydrobenzene;
Hexanaphthene;
Cyclohexan;
Cykloheksan;
Cicloesano;
Cyclohexaan;
Benzene, hexahydro-;
Benzenehexahydride;
Polycyclohexane;
hexahydro-Benzene;
Poly(cyclohexane);
RCRA waste number U056;
cyclo-hexane;
UNII-48K5MKG32S;
MFCD00003814
NSC 406835;
Cyclohexane, oxidized, non-volatile residue;
Cyclohexane, ACS reagent;
Cyclohexane, HPLC Grade;
Cyclohexane, 99+%, pure;
Cyclohexan [German];
Cicloesano [Italian];
Cykloheksan [Polish];
Caswell No. 269;
Ciclohexano;
Cyclohexane, 99.5%, extra pure;
Cyclohexane, 99.8%, for HPLC;
Cyclohexane, 99.5%, for analysis;
Cyclohexane, ACS reagent, >=99%;
Cyclohexane, 99+%, for spectroscopy;
Cyclohexane, for HPLC, >=99.7%;
HSDB 60;
Cyclohexane, 99+%, for spectroscopy ACS;
Cyclohexane, for pesticide residue analysis;
CCRIS 3928;
Cyclohexane, 99.5%, Extra Dry, AcroSeal(R);
EINECS 203-806-2;
UN1145;
RCRA waste no. U056;
EPA Pesticide Chemical Code 025901