Benzene dicarbonitrile

Benzene dicarbonitrile
Surname	Benzene-1,2-dicarbonitrile	Benzene-1,3-dicarbonitrile	Benzene-1,4-dicarbonitrile
other names	o -Benzenedinitrile, phthalic acid dinitrile, phthalonitrile , 1,2-dicyanobenzene	m -Benzenedinitrile, isophthalic acid dinitrile, isophthalonitrile, 1,3-dicyanobenzene	p -Benzenedinitrile, terephthalic acid dinitrile, terephthalodinitrile, 1,4-dicyanobenzene
Structural formula
CAS number	91-15-6	626-17-5	623-26-7
PubChem	7042	12276	12172
Molecular formula	C 8 H 4 N 2
Molar mass	128.13 g mol −1
Physical state	firmly
Brief description	beige crystalline odorless powder	colorless crystalline powder with a smell of bitter almonds	colorless crystals with a smell of bitter almonds
Melting point	138-141 ° C	162-163 ° C	224-227 ° C
boiling point		288 ° C
Solubility in water	0.56 g l −1 (25 ° C)	0.7 g l −1 (20 ° C)	0.08 g l −1 (23 ° C)
GHS labeling	danger	Caution	Caution
H and P phrases	301 + 311 + 331-412	302 + 332	315-319-335
	no EUH phrases	no EUH phrases	no EUH phrases
	273-501	no P-phrases	261-305 + 351 + 338
MAK		Switzerland: 5 mg m −3 ( inhalable dust )
LD 50	30 mg kg −1 (rat, oral)	860 mg kg −1 (rat, oral)	> 6400 mg kg −1 (rat, oral)

The Phthalonitrile form a in the chemical substance group consisting of a benzene ring with two appended nitrile groups  consist (-CN). Their different arrangements ( ortho , meta or para ) result in three constitutional isomers with the empirical formula C ₈ H ₄ N ₂ .

The common names (phthalic acid dinitrile, isophthalic acid dinitrile, terephthalic acid dinitrile) are derived in a corresponding manner from the benzene dicarboxylic acids ( phthalic acid , isophthalic acid , terephthalic acid ).

history

The first presentation of phthalonitrile was reported by Johannes Pinnow in 1896 . It was discovered as a by-product in the reaction between orthoamidobenzonitrile hydrochloride , sodium nitrite and hydrochloric acid to synthesize orthodicyanodiazoamidobenzene . The first direct method of making phthalonitrile was introduced in 1907 with the reaction of phthalamide with acetic anhydride . Although the initial yields were small, it became the forerunner of today's large-scale synthesis processes.

presentation

Phthalonitrile may be in a single-step process by ammoxidation of o -xylene of a in the presence of vanadium - antimony oxide - catalyst at high temperatures (480 ° C) are obtained.

Terephthalonitrile can also be obtained by ammoxidation of p- xylene .

Three other methods are described for the production of phthalonitrile:

1. Of phthalic anhydride and ammonia is phthalimide prepared which when further addition of ammonia to phthalamide is reacted. This is treated in pyridine or chlorobenzene as a solvent with dehydrating agents such as phosphorus pentachloride , whereby phthalonitrile is formed.
2. Using bauxite as a catalyst, phthalic anhydride and ammonia are allowed to react in the gas phase, phthalonitrile being formed in one step.
3. By reacting ammonia with a xylene mixture, phthalonitrile, isophthalonitrile and terephthalodinitrile are obtained. From 1935 to 1966, phthalonitrile was manufactured from phthalic anhydride at BASF AG; from 1966, it was manufactured using o- xylene by ammoxidation at temperatures of up to 500 ° C.

properties

Terephthalonitrile has the highest melting point due to the greatest molecular symmetry. o -Phthalonitrile is readily soluble in alcohol, ether and chloroform and very soluble in benzonitrile .

use

Phthalonitrile is used in the manufacture of phthalocyanine dyes and is found in electrophotographic materials.

Phthalonitrile is also used in the manufacture of pesticides, as a stabilizing additive for aircraft fuels, and in the rubber industry. It is also used as a starting product for the production of optical brighteners and sensitizers for photography.

Web links

• Recovery of Terephthalonitrile

Individual evidence

1. ↑ ^{a b c d} Entry for CAS no. 91-15-6 in the GESTIS substance database of the IFA , accessed on July 28, 2017(JavaScript required) .
2. ↑ ^{a b c d e} Entry for CAS no. 626-17-5 in the GESTIS substance database of the IFA , accessed on July 28, 2017(JavaScript required) .
3. ↑ ^{a b c d} Entry for CAS no. 623-26-7 in the GESTIS substance database of the IFA , accessed on July 28, 2017(JavaScript required) .
4. ↑ Swiss Accident Insurance Fund (Suva): Limit values ​​- current MAK and BAT values (search for 626-17-5 or 1,3-phthalic acid dinitrile ), accessed on February 12, 2020.
5. ↑ Johannes Pinnow, C. Sämann: About derivatives of o-amidobenzonitrile ; in: Reports of the German Chemical Society ; 1896 ; 29  (1); Pp. 623-632; doi : 10.1002 / cber.189602901118 .
6. ↑ A. Braun, J. Tcherniac: About the products of the action of acetic anhydride on phthalamide ; in: Reports of the German Chemical Society ; 1907 ; 40  (2); Pp. 2709-2714; doi : 10.1002 / cber.190704002202 .
7. ↑ Peter M. Lorz, Friedrich K. Towae, Walter Enke, Rudolf Jäckh, Naresh Bhargava, Wolfgang Hillesheim: Phthalic Acid and Derivatives . Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim 2002; doi : 10.1002 / 14356007.a20_181.pub2 .
8. ↑ ^{a b c} Toxicological evaluation of o-phthalonitrile (PDF) at the professional association for raw materials and chemical industry (BG RCI), accessed on August 22, 2012.