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It is a colorless, sweet-smelling liquid that catches on fire easily. It occurs naturally in petroleum and coal tar and is formed during forest fires. Xylene in air can be smelled at 0.08 to 3.7 parts of xylene per million parts of air (ppm) and begin to taste it in water at 0.53 to 1.8 ppm.

Chemical industries produce xylene from petroleum. It's one of the top 30 chemicals produced in the United States in terms of volume. Xylene is used as a solvent and in the printing, rubber, and leather industries. p-Xylene is used as a feedstock in the production of terephthalic acid, which in turn is a monomer used in the production of polymers. It is also used as a cleaning agent , a thinner for paint, and in paints and varnishes. It is found in small amounts in airplane fuel and gasoline.

1 Structure

Background: HydrocarbonIn chemistry, a hydrocarbon is an organic compound consisting only of carbon and hydrogen. They all consist of carbon backbone and atoms of hydrogen attached to that backbone, also aliphatic hydrocarbons. For example, methane ( swamp gas) is a hydrocarbons can be divided into two main groups, aliphaticIn chemistry, non- aromatic organic compounds are called aliphatic . They include not only the fatty acids and other derivatives of the paraffin hydrocarbons, but also unsaturated compounds, such as the ethylene ( alkene) and acetylene ( alkyne) series.s and aromaticIn chemistry, an aromatic molecule is one in which electrons are free to cycle around circular arrangements of atoms, which are alternately singly and doubly bonded to one another. More properly, these bonds may be seen as a hybrid of a single bond and as. Aliphatics are further subdivided into alkaneAn alkane in organic chemistry is a type of hydrocarbon in which the molecule has the maximum possible number of hydrogen atoms and so has no double bonds (they are saturated). The generic formula for acyclic alkanes, also known as aliphatic hydrocarbonss, alkeneAn alkene is one of the three classes of unsaturated hydrocarbons that contain at least one carbon- carbon double bond and have the general molecular formula of CH (the other two being alkynes and arenes). The simplest alkene is CH, which has the common ns, alkyneAlkynes are hydrocarbons that have at least one triple bond between carbon atoms. The alkynes are traditionally known as acetylenes though the name acetylene is also used to refer specifically to the simplest member of the series, known officially as ethys and cycloaliphatic s. Cycloaliphatics are further subdivided into cycloalkanes, cycloalkenes and cycloalkynes. The difference between them is that cycloalkanes have all single bonds, cycloalkenes have one or more double bonds and cycloalkynes have one or more triple bonds. When speaking of hybridization I will speak of it relative to most of the molecule, considering that most of the carbons in the cycloaliphatic molecule have single bonds to the rest of the carbons (sp3 hybridized). sp3 hybridization tends to create a 109 degree angle of separation between the carbon-carbon single bond. No single cycloaliphatic actually reaches a full 109 degree angle of separation, ( this can be proved mathematically) and most have to twist in order to avoid stress. This means that most cycloaliphatics (except cyclopropane) are twisted. In turn aromatic hydrocarbons, which are mostly cyclic, have alternating double bond-single bonds. This allows all of the carbons in the main chains to be sp2 hybridized which make an angle of 120 degrees with each other. Benzene is the only aromatic compound which has 6 carbons in the main ring. From mathematics we know that the corners of a hexagon have an angle of 120 degrees.

Theory: Xylenes, like normal benzene have a planar structure which makes them very stable. They are soluble in alcohol and ether, but insoluble in water. Xylenes are often mixed with ethylbenzene when preparing industrial and commercial solutions of the isomers. Each mix is colorless at room temperature. para-xylene forms crystals at high temperatures.