Nitroxylenes

The nitroxylenes (also called dimethylnitrobenzenes or nitroxylenes ) form a group of substances that are derived from toluene or xylenes as well as from nitrobenzene . The structure consists of a benzene ring with two attached methyl groups  (-CH ₃ ) and a nitro group  (-NO ₂ ) as substituents . Their different arrangement results in six constitutional isomers with the empirical formula C ₈ H ₉ NO ₂ . They are obtained by nitrating xylene and were first systematically studied by Emilio Noelting in 1885 . Depending on the degree of nitration, they are divided into:

• Nitroxylenes (mononitroxylenes): six constitutional isomers
• Dinitroxylenes
• Trinitroxylenes

Extraction and properties

The nitroxylenes be nitriding (for example, with a. Nitric acid - sulfuric acid mixture) of xylene recovered; the conversion of m-xylene produces an isomer mixture of 75% 2,4-dimethylnitrobenzene (4-nitro- m -xylene), 25% 2,6-dimethylnitrobenzene (2-nitro- m -xylene), and a little 3.5 -Dimethylnitrobenzene (5-nitro- m -xylene). They occur here as yellowish liquids that are poorly soluble in water, but soluble in organic solvents. The average density is 1.12 g / cm ³ ; the nitroxylenes are therefore all heavier than water.

The nitroxylenes have a low acute oral toxicity ( LD ₅₀ µm or above 2000 mg / kg in female rats), there is evidence of a mutagenic effect for most of the isomers.

Nitroxylenes
Surname	2,3-dimethyl- nitrobenzene	2,4-dimethyl- nitrobenzene	2,5-dimethyl- nitrobenzene	2,6-dimethyl- nitrobenzene	3,4-dimethyl- nitrobenzene	3,5-dimethyl- nitrobenzene
other names	3-nitro- o- xylene	4-nitro- m- xylene	2-nitro- p- xylene	2-nitro- m- xylene	4-nitro- o- xylene	5-nitro- m- xylene
Structural formula
CAS number	83-41-0	89-87-2	89-58-7	81-20-9	99-51-4	99-12-7
	25168-04-1 (mixture of isomers)
PubChem	6739	6991	6974	6672	7440	7426
Molecular formula	C 8 H 9 NO 2
Molar mass	151.16 g mol −1
Physical state	liquid				firmly
Brief description	yellowish liquid				yellow, crystalline solids
Melting point	15 ° C	2 ° C	2 ° C	14-16 ° C	30.5-32 ° C	72-74 ° C
boiling point	240-245 ° C	245 ° C	240 ° C	222-224 ° C	255-257 ° C	273 ° C (985 hPa)
solubility	poorly soluble in water, soluble in ethanol, ether and chloroform
GHS labeling	Caution	Caution	no GHS pictograms	Caution	Caution	Caution
H and P phrases	312-319	302	no H-phrases	312-332-411	302	302-312-332
	no EUH phrases	no EUH phrases	no EUH phrases	no EUH phrases	no EUH phrases	no EUH phrases
	261-280-302 + 352 304 + 340-322-501	no P-phrases	no P-phrases	261-280-302 + 352 304 + 340-322-501	no P-phrases	261-280-302 + 352 304 + 340-322-501

use

Nitroxylenes are used as intermediates in the manufacture of dyes (e.g. xylidines ), insecticides, herbicides, and pharmaceuticals. Nitro o -xylene is used to produce 3,4- xylidine used in the several stages of riboflavin (vitamin B ₂ is produced). Since nitroxylenes are also used in the manufacture of explosives , they, like nitrotoluenes and 2,4-dinitrotoluene, can be detected as old armaments in the soil and groundwater.

Web links

Commons : Nitroxylenes  - Collection of pictures, videos and audio files

Individual evidence

1. ↑ ^{a b} Production of nitroxylenes ( Memento from March 9, 2012 in the Internet Archive ).
2. ↑ Comparative consideration of the toxicological effects of five different nitroxylenes  ( page no longer available , search in web archives )  Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice. (PDF; 58 kB), accessed on August 22, 2012.  
3. ↑ ^{a b c} Entry for CAS no. 83-41-0 in the GESTIS substance database of the IFA , accessed on October 14, 2012(JavaScript required) .
4. ↑ ^{a b c} Entry for CAS no. 89-87-2 in the GESTIS substance database of the IFA , accessed on October 14, 2012(JavaScript required) .
5. ↑ ^{a b c} Entry for CAS no. 89-58-7 in the GESTIS substance database of the IFA , accessed on October 14, 2012(JavaScript required) .
6. ↑ ^{a b c} Entry for CAS no. 81-20-9 in the GESTIS substance database of the IFA , accessed on October 14, 2012(JavaScript required) .
7. ↑ ^{a b c} Entry for CAS no. 99-51-4 in the GESTIS substance database of the IFA , accessed on October 14, 2012(JavaScript required) .
8. ↑ ^{a b c} Entry for CAS no. 99-12-7 in the GESTIS substance database of the IFA , accessed on October 14, 2012(JavaScript required) .
9. ↑ Toxicological assessment of 4-nitro-1,3-dimethylbenzene (PDF) at the professional association raw materials and chemical industry (BG RCI), accessed on August 22, 2012.
10. ↑ Toxicological evaluation from page no longer available , search in web archives: 4-Nitro-1,2-dimethylbenzene  ( page no longer available , search in web archives )  Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice. (PDF) from the trade association raw materials and chemical industry (BG RCI), accessed on August 22, 2012.