13.8: Structure and Nomenclature of Aromatic Compounds, [ "article:topic", "showtoc:no", "license:ccbyncsa", "program:hidden" ], 13.E: Unsaturated and Aromatic Hydrocarbons (Exercises), To Your Health: Polycyclic Aromatic Hydrocarbons and Cancer, Biologically Important Compounds with Benzene Rings, starting material for the synthesis of dyes, drugs, resins, varnishes, perfumes; solvent; vulcanizing rubber, food preservative; starting material for the synthesis of dyes and other organic compounds; curing of tobacco, starting material for the synthesis of many other aromatic compounds; solvent; motor oil additive, starting material for the synthesis of aniline; solvent for cellulose nitrate; in soaps and shoe polish, disinfectant; starting material for the synthesis of resins, drugs, and other organic compounds, solvent; gasoline octane booster; starting material for the synthesis of benzoic acid, benzaldehyde, and many other organic compounds. Figure \(\PageIndex{1}\) shows four examples. AlCl3 to give: See: Kolmetz, Gentry, Guidelines for BTX Revamps, AIChE 2007 Spring Conference. How do you name a benzene ring with a -OH, a -CHO, and an -OCH3 attached to it in 2,4,6 respectively? Answer Save. We also acknowledge previous National Science Foundation support under grant numbers 1246120, 1525057, and 1413739. Benzene: Patient information sheet, Drinking Water Contaminants|Organic Chemicals|Benzene, Benzene Toxicity: Standards and Regulations|ATSDR – Environmental Medicine & Environmental Health Education – CSEM, Documentation for Immediately Dangerous to Life or Health Concentrations (IDLH): Introduction, "Blood concentrations of volatile organic compounds in a nonoccupationally exposed US population and in groups with suspected exposure", "100 tonnes of pollutants spilled into Chinese river", "A Former Nazi Labor Camp in Austria, Now Billed as a Tourist Site", Dept. [95][96], This article is about the chemical compound. To accurately reflect the nature of the bonding, benzene is often depicted with a circle inside a hexagonal arrangement of carbon atoms. Similarly, the Friedel-Crafts acylation is a related example of electrophilic aromatic substitution. The United States Environmental Protection Agency introduced new regulations in 2011 that lowered the benzene content in gasoline to 0.62%. A typical reaction yield exceeds 95%. This reaction is practiced on a large scale industrially. Phenol and halobenzenes can be reduced with metals. Toluene hydrodealkylation converts toluene to benzene. (1867) "Theoretische Betrachtungen und deren Anwendungen zur Systematik der organischen Chemie" (Theoretical considerations and their applications to the classification scheme of organic chemistry). Benzene is an organic chemical compound with the molecular formula C6H6. As a gasoline (petrol) additive, benzene increases the octane rating and reduces knocking. [86] Benzene causes chromosomal aberrations in the peripheral blood leukocytes and bone marrow explaining the higher incidence of leukemia and multiple myeloma caused by chronic exposure. [13] Michael Faraday first isolated and identified benzene in 1825 from the oily residue derived from the production of illuminating gas, giving it the name bicarburet of hydrogen. [44], Trace amounts of benzene are found in petroleum and coal. Benzene has been shown to cause cancer in both sexes of multiple species of laboratory animals exposed via various routes. [92], Under specific conditions and in the presence of other chemicals benzoic acid (a preservative) and ascorbic acid (Vitamin C) may interact to produce benzene. Pyrolysis gasoline can be blended with other hydrocarbons as a gasoline additive, or routed through an extraction process to recover BTX aromatics (benzene, toluene and xylenes). Sulfonated benzene derivatives are useful detergents. The next year he published a much longer paper in German on the same subject. Toluene disproportionation (TDP) is the conversion of toluene to benzene and xylene. Under these conditions, toluene undergoes dealkylation to benzene and methane: This irreversible reaction is accompanied by an equilibrium side reaction that produces Outdoor air may contain low levels of benzene from automobile service stations, wood smoke, tobacco smoke, the transfer of gasoline, exhaust from motor vehicles, and industrial emissions. Benzene reacts with CH3COCl in the presence of anhyd. of Health and Human Services: TR-289: Toxicology and Carcinogenesis Studies of Benzene, NLM Hazardous Substances Databank – Benzene, https://en.wikipedia.org/w/index.php?title=Benzene&oldid=986689143#Structure, GABAA receptor positive allosteric modulators, Wikipedia pages move-protected due to vandalism, Short description is different from Wikidata, Pages using collapsible list with both background and text-align in titlestyle, Articles containing unverified chemical infoboxes, Creative Commons Attribution-ShareAlike License, potential occupational carcinogen, flammable. An aromatic compound is any compound that contains a benzene ring or has certain benzene-like properties. In 2013, the biggest consumer country of benzene was China, followed by the USA. Many important chemical compounds are derived from benzene by replacing one or more of its hydrogen atoms with another functional group. [60] Highly instructive but of far less industrial significance is the Friedel-Crafts alkylation of benzene (and many other aromatic rings) using an alkyl halide in the presence of a strong Lewis acid catalyst. Myeloperoxidase mutations result in loss of function and may result in decreased generation of toxic metabolites. The compound is therefore named as a derivative of toluene. [72] The maximum allowable amount of benzene in workroom air during an 8-hour workday, 40-hour workweek is 1 ppm. Favorite Answer. These intermediates and metabolites induce genotoxicity by multiple mechanisms including inhibition of topoisomerase II (which maintains chromosome structure), disruption of microtubules (which maintains cellular structure and organization), generation of oxygen free radicals (unstable species) that may lead to point mutations, increasing oxidative stress, inducing DNA strand breaks, and altering DNA methylation (which can affect gene expression). Naphthalene has a pungent odor and is used in mothballs. But I guess you mean (CH3)3C- or (CH3)3C-R, which is a tert-butyl substituent. As benzene has a high octane number, aromatic derivatives like toluene and xylene typically comprise up to 25% of gasoline (petrol). Centric affinities (i.e., bonds) acted within a designated cycle of carbon atoms. [33] This vision, he said, came to him after years of studying the nature of carbon-carbon bonds. Today, most benzene comes from the petrochemical industry, with only a small fraction being produced from coal.[45]. Agency for Toxic Substances and Disease Registry.

Sulfonation of benzene involves the use of oleum, a mixture of sulfuric acid with sulfur trioxide. [54], Four chemical processes contribute to industrial benzene production: catalytic reforming, toluene hydrodealkylation, toluene disproportionation, and steam cracking. These aberrations can be monitored using fluorescent in situ hybridization (FISH) with DNA probes to assess the effects of benzene along with the hematological tests as markers of hematotoxicity. Benzene targets the liver, kidney, lung, heart and brain and can cause DNA strand breaks, chromosomal damage, etc.

Some common aromatic hydrocarbons consist of fused benzene rings—rings that share a common side. The three examples shown here are colorless, crystalline solids generally obtained from coal tar.

This is so that you are sure that the chlorine is part of the methyl group and not somewhere else on the ring. Relevance. The substituent names are listed in alphabetical order. Important examples include the sandwich and half-sandwich complexes, respectively, Cr(C6H6)2 and [RuCl2(C6H6)]2. [12] An acidic material was derived from benzoin by sublimation, and named "flowers of benzoin", or benzoic acid.

Most of these metabolites have some value as biomarkers of human exposure, since they accumulate in the urine in proportion to the extent and duration of exposure, and they may still be present for some days after exposure has ceased. In his 1890 paper, Armstrong represented benzene nuclei within polycyclic benzenoids by placing inside the benzene nuclei a letter "C", an abbreviation of the word "centric". Pure benzene, for example, oxidizes in the body to produce an epoxide, benzene oxide, which is not excreted readily and can interact with DNA to produce harmful mutations. The current NIOSH definition for an IDLH condition, as given in the NIOSH Respirator Selection Logic, is one that poses a threat of exposure to airborne contaminants when that exposure is likely to cause death or immediate or delayed permanent adverse health effects or prevent escape from such an environment [NIOSH 2004]. 6-membered aromatic rings with one carbon replaced by another group: This page was last edited on 2 November 2020, at 11:54. It is a byproduct of the incomplete combustion of many materials. (VIII. The U.S. Occupational Safety and Health Administration (OSHA) has set a permissible exposure limit of 1 part of benzene per million parts of air (1 ppm) in the workplace during an 8-hour workday, 40-hour workweek. The most common aryl group is derived from benzene (C6H6) by removing one hydrogen atom (C6H5) and is called a phenyl group, from pheno, an old name for benzene. Trimerization of acetylene gives benzene. The simplified formula for this is C 6 H 5 CH 3. After exposure to 63 to 405 mg/m3 of benzene for 1 to 5 hours, 51 to 87% was excreted in the urine as phenol over a period of 23 to 50 hours. Thus, a double bond would exist with one neighbor during the first interval and with the other neighbor during the next interval. [61][62][63] The specific hematologic malignancies that benzene is associated with include: acute myeloid leukemia (AML), aplastic anemia, myelodysplastic syndrome (MDS), acute lymphoblastic leukemia (ALL), and chronic myeloid leukemia (CML).[64]. The benzene ring has two chlorine atoms (dichloro) in the first and second positions.

Benzene itself has been limited to less than 1% in gasoline because it is a known human carcinogen. [90] After smoking 32 cigarettes per day, the smoker would take in about 1.8 milligrams (mg) of benzene. Benzene is a natural constituent of crude oil and is one of the elementary petrochemicals. For other uses, see, Except where otherwise noted, data are given for materials in their, Biological oxidation and carcinogenic activity, Critics pointed out a problem with Kekulé's original (1865) structure for benzene: Whenever benzene underwent substitution at the ortho position, two distinguishable isomers should have resulted, depending on whether a double bond or a single bond existed between the carbon atoms to which the substituents were attached; however, no such isomers were observed. Substantial quantities of epidemiologic, clinical, and laboratory data link benzene to aplastic anemia, acute leukemia, bone marrow abnormalities and cardiovascular disease. These genes may be targets for genetic screening for susceptibility to benzene toxicity. The Nazis used benzene administered via injection as one of their many methods of killing.