Xylene

Xylene is used as a solvent. In this application, with a mixture of isomers, it is often referred to as xylenes or xylol. Areas of application include the printing, rubber, and leather industries. It is a common component of ink, rubber, and adhesives. In thinning paints and varnishes, it can be substituted for toluene where slower drying is desired, and thus is used by conservators of art objects in solubility testing. Similarly it is a cleaning agent, e.g., for steel, silicon wafers, and integrated circuits. In dentistry, xylene can be used to dissolve gutta percha, a material used for endodontics (root canal treatments). In the petroleum industry, xylene is also a frequent component of paraffin solvents, used when the tubing becomes clogged with paraffin wax. For similar reasons, it is often the active ingredient in commercial products for ear wax removal.

Laboratory use

Xylene is used in the laboratory to make baths with dry ice to cool reaction vessels, and as a solvent to remove synthetic immersion oil from the microscope objective in light microscopy. In histology, xylene is the most widely used clearing agent. Xylene is used to remove paraffin from dried microscope slides prior to staining. After staining, microscope slides are put in xylene prior to mounting with a coverslip.

Precursor to other compounds

Although conversion to terephthalic acid is the dominant chemical conversion, xylenes are precursors to other chemical compounds. For instance chlorination of both methyl groups gives the corresponding xylene dichlorides (bis(chloromethyl)benzenes) whilst mono-bromination yields xylyl bromide.

P-Xylene

Properties	Unit	Spec 1	Spec 2	Spec 3	Test Method
P – Xylene	%Wt	99.7 Min	99.7 min	99.7 min	ASTM D 3798
O – Xylene	%Wt	0.9 Max	0.1 max	0.1 max	ASTM D 3798
M – Xylene	%Wt	0.19 Max	0.3 max	0.25 max	ASTM D 3798
Non – Aromatic	%Wt	0.01 Max	0.2 max	0.2 max	ASTM D 3798
Benzene + Toluene	%Wt	0.01 Max		0.03 max	ASTM D 3798
Toluene	%Wt	–	0.1 max		ASTM D 3798
Ethylbenzene	%Wt	0.15 Max	0.5 max	0.3 max	ASTM D 3798
Total Sulfur	ppm (wt)	1.0 Max	1.0 max	1 max	ASTM D 5453
Organic Chloride	ppm (wt)	1.0 Max	–	1 max	ASTM D5808
Acid Wash Color		1.0 Max	–	1 max	ASTM D 848
SO₂/ H₂S Content		nil	Free	Free	ASTM D 853
Distillation Range	°C	1.0 Max	20 max including 138.3	138.4 ± 2 max	ASTM D 850
Color	Pt – Co	10.0 Max	20 max	20 max	ASTM D 1209
Sp – GR @ 15.56 °C /15.56°C	–	0.858 – 0.875	0.865 – 0.867	0.8650 – 0.8661	ASTM D 4052
Vapor pressure	psi	–	0.3	–	ASTM D 323-99A
Appearance	–	Clear Liquid free of Sedimentation or haze & 18.3 to 25.6 °C	Clear liquid free of sedimentation or haze at 18.3 to 25.6°C	Colorless Clear	Visual

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O-Xylene

Properties	Unit	Specification	Test Method
Purity	%Wt	98.0 min	UOP 744-86
Non aromatics	%Wt	0.5 max	ASTM 2360-82
Benzene plus C9 and heavier aromatics	%Wt	1.0 max	UOP 744-86
Ortho, Meta & Para Xylene plus Toluene plus Ethylbenzene	%Wt	98.5 min	UOP 744-86
Distillation range @760 mm Hg	°C	2.0 max including 144.4	ASTM D 850-79
Total Sulfur	ppm (wt)	1.0 max	ASTM D 4045-87
Color	Pt-Co	20 max	ASTM D 1209-84
Acidity		None detected	ASTM D 847-87
Hydrocarbon residue after evaporation	ppm (wt)	20 max	ASTM D 1353-86
SO₂ / H₂S		None detected	ASTM D 853-82
Vapor Pressure	psi	0.3	ASTM D 323-99A
Specific Gravity at 15.56/15.56 °C		0.88 – 0.89	ASTM D 4052-86

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Mix Xylene

Properties	Unit	Spec 1	Spec 2	Test Method
Non aromatics	%Wt	3.0 max	0.1 max	ASTM D 2360-82
Distillation range @760 mm HG	°C	10.0 max	5 max	ASTM D 850-79
Initial Boiling point @760 mm Hg	°C	135 min	137 min	ASTM D 850-79
Dry point @760 mm Hg	°C	145 max	143 max	ASTM D 850-79
Appearance		Clear liquid free of sedimentation or haze at 18.3 to 25.6 °C	Clear free of Haze/sediment	VISUAL
Copper corrosion		pass (1a to 1b)	No. 1a	ASTM D 849-88
Color	Pt-Co	20 max	10 max	ASTM D 1209-84
Acid wash color		6 max	2 max	ASTM D 848-81
Acidity		None detected	No Free Acid	ASTM D 847-87
Specific Gravity at 15.56/15.56 °C		0.865 – 0.877	To be Reported	ASTM D 4052-86
SO₂ / H₂S		None detected	Free	ASTM D 853-82
Vapor Pressure	psi	0.1	–	ASTM D 323-99A/td>
Para-xylene	%Wt	–	16 min	D-2306
Ortho-xylene	%Wt	–	16 min	D-2306
Ethyl Benzene	%Wt	–	18.5 max	D-2306
Meth- xylene	%Wt	–	49 max	D-2306
Benzene	%Wt	–	0.005 max	D-2360
Toluene	%Wt	–	0.04 max	D-2360
C₉ Aromatics	%Wt	–	0.5 max	D-2360
Total Sulfur	ppm (wt)	–	1 max	UOP 727
Total Chlorides	ppm (wt)	–	1 max	IP-AK/81
Bromine Index	mg/100g	–	20 max	IP-129 (MODIFIED)