If the acid is a carboxylic acid (−C(=O)OH), the compound contains a −C(=O)Xfunctional group, which consists of a carbonyl group (C=O) singly bonded to a halogen atom.[3] The general formula for such an acyl halide can be written RCOX, where R may be, for example, an alkyl group, CO is the carbonyl group, and X represents the halide, such as chloride. Acyl chlorides are the most commonly encountered acyl halides, but acetyl iodide is the one produced (transiently) on the largest scale. Billions of kilograms are generated annually in the production of acetic acid.[4]
Of commercial interest, acyl chlorides react with HF to give acyl fluorides.[11] Aromatic (as well as aliphatic) acyl fluorides are conveniently prepared directly from carboxylic acids, using stable, inexpensive commodity chemicals: PPh3, NBS and Et3N-3HF in a bench-top protocol.[12]Cyanuric fluoride converts carboxylic acids to acyl fluorides.
Acyl bromides and iodides
Acyl bromides and iodides are synthesized accordingly but are less common.[13]
Reactions
Acyl halides are rather reactive compounds often synthesized to be used as intermediates in the synthesis of other organic compounds. For example, an acyl halide can react with:
water, to form a carboxylic acid. This hydrolysis is the most heavily exploited reaction for acyl halides as it occurs in the industrial synthesis of acetic acid.
A molecule can have more than one acyl halide functional group. For example, "adipoyl dichloride", usually simply called adipoyl chloride, has two acyl chloride functional groups; see the structure at right. It is the dichloride (i.e., double chloride) of the 6-carbon dicarboxylic acid adipic acid. An important use of adipoyl chloride is polymerization with an organic di-amino compound to form a polyamide called nylon or polymerization with certain other organic compounds to form polyesters.
Phosgene (carbonyl dichloride, Cl–CO–Cl) is a very toxic gas that is the dichloride of carbonic acid (HO–CO–OH). Both chloride radicals in phosgene can undergo reactions analogous to the preceding reactions of acyl halides. Phosgene is used a reactant in the production of polycarbonate polymers, among other industrial applications.
General hazards
Volatile acyl halides are lachrymatory because they can react with water at the surface of the eye producing hydrohalic and organic acids irritating to the eye. Similar problems can result if one inhales acyl halide vapors. In general, acyl halides (even non-volatile compounds such as tosyl chloride) are irritants to the eyes, skin and mucous membranes.
^Hosea Cheung, Robin S. Tanke, G. Paul Torrence "Acetic Acid" in Ullmann's Encyclopedia of Industrial Chemistry 2002, Wiley-VCH, Weinheim. doi:10.1002/14356007.a01_045
^Adams, Roger (1923). "p-Nitrobenzoyl chloride". Organic Syntheses. 3: 75. doi:10.15227/orgsyn.003.0075.
^Clarke, H. T.; Taylor, E. R. (1929). "o-Chlorobenzoyl chloride". Organic Syntheses. 9: 34. doi:10.15227/orgsyn.009.0034.
^Olah G, Kuhn S (1961). "Preparation of Acyl Fluorides with Anhydrous Hydrogen Fluoride. The General Use of the Method of Colson and Fredenhagen". J. Org. Chem. 26: 237–238. doi:10.1021/jo01060a600.
^Munoz, Socrates B.; Dang, Huong; Ispizua-Rodriguez, Xanath; Mathew, Thomas; Prakash, G. K. Surya (2019-03-15). "Direct Access to Acyl Fluorides from Carboxylic Acids Using a Phosphine/Fluoride Deoxyfluorination Reagent System". Organic Letters. 21 (6): 1659–1663. doi:10.1021/acs.orglett.9b00197. ISSN 1523-7060. PMID 30840474. S2CID 73481495.
^Keinan, Ehud; Sahai, M. (June 1990). "Diiodosilane. 3. Direct synthesis of acyl iodides from carboxylic acids, esters, lactones, acyl chlorides and anhydrides". The Journal of Organic Chemistry. 55 (12): 3922–3926. doi:10.1021/jo00299a042. ISSN 0022-3263.
^Allen, C. F. H.; Kibler, C. J.; McLachlin, D. M.; Wilson, C. V. (1946). "Acid Anhydrides". Organic Syntheses. 26: 1–3. doi:10.15227/orgsyn.026.0001. PMID 20280752.
External links
Wikiquote has quotations related to Acyl halide.
March 03, 2023
acyl, halide, organic, chemistry, acyl, halide, also, known, acid, halide, chemical, compound, derived, from, oxoacid, replacing, hydroxyl, group, with, halide, group, where, halogen, acyl, halide, acid, carboxylic, acid, compound, contains, functional, group,. In organic chemistry an acyl halide also known as an acid halide is a chemical compound derived from an oxoacid 1 by replacing a hydroxyl group OH with a halide group X where X is a halogen 2 Acyl Halide If the acid is a carboxylic acid C O OH the compound contains a C O X functional group which consists of a carbonyl group C O singly bonded to a halogen atom 3 The general formula for such an acyl halide can be written RCOX where R may be for example an alkyl group CO is the carbonyl group and X represents the halide such as chloride Acyl chlorides are the most commonly encountered acyl halides but acetyl iodide is the one produced transiently on the largest scale Billions of kilograms are generated annually in the production of acetic acid 4 Contents 1 Preparation 1 1 Aliphatic acyl halides 1 2 Aromatic acyl chlorides 1 3 Acyl fluorides 1 4 Acyl bromides and iodides 2 Reactions 3 Multiple functional groups 4 General hazards 5 References 6 External linksPreparation EditAliphatic acyl halides Edit On an industrial scale the reaction of acetic anhydride with hydrogen chloride produces a mixture of acetyl chloride and acetic acid 5 CH 3 CO 2 O HCl CH 3 COCl CH 3 CO 2 H displaystyle ce CH3CO 2O HCl gt CH3COCl CH3CO2H Common syntheses of acyl chlorides also entail the reaction of carboxylic acids with phosgene thionyl chloride 6 and phosphorus trichloride 7 Phosphorus pentabromide is used for acyl bromides which are rarely of value Aromatic acyl chlorides Edit Benzoyl chloride is produced from benzotrichloride using either water or benzoic acid 8 C 6 H 5 CCl 3 H 2 O C 6 H 5 COCl 2 HCl displaystyle ce C6H5CCl3 H2O gt C6H5COCl 2 HCl C 6 H 5 CCl 3 C 6 H 5 CO 2 H 2 C 6 H 5 COCl HCl displaystyle ce C6H5CCl3 C6H5CO2H gt 2 C6H5COCl HCl As with other acyl chlorides it can be generated from the parent acid and other chlorinating agents phosphorus pentachloride or thionyl chloride Representative laboratory routes to aromatic acyl halides are comparable to those for aliphatic acyl halides 9 For example chloroformylation a specific type of Friedel Crafts acylation which uses formaldehyde as a reagent citation needed or by the direct chlorination of benzaldehyde derivatives 10 Acyl fluorides Edit Of commercial interest acyl chlorides react with HF to give acyl fluorides 11 Aromatic as well as aliphatic acyl fluorides are conveniently prepared directly from carboxylic acids using stable inexpensive commodity chemicals PPh3 NBS and Et3N 3HF in a bench top protocol 12 Cyanuric fluoride converts carboxylic acids to acyl fluorides Acyl bromides and iodides Edit Acyl bromides and iodides are synthesized accordingly but are less common 13 Reactions EditAcyl halides are rather reactive compounds often synthesized to be used as intermediates in the synthesis of other organic compounds For example an acyl halide can react with water to form a carboxylic acid This hydrolysis is the most heavily exploited reaction for acyl halides as it occurs in the industrial synthesis of acetic acid an alcohol to form an ester an amine to form an amide an aromatic compound using a Lewis acid catalyst such as AlCl3 to form an aromatic ketone 7 See Friedel Crafts acylation carboxylic acids to form an organic acid anhydrides 14 In the above reactions HX hydrogen halide or hydrohalic acid is also formed For example if the acyl halide is an acyl chloride HCl hydrogen chloride or hydrochloric acid is also formed Multiple functional groups Edit Adipoyl chloride A molecule can have more than one acyl halide functional group For example adipoyl dichloride usually simply called adipoyl chloride has two acyl chloride functional groups see the structure at right It is the dichloride i e double chloride of the 6 carbon dicarboxylic acid adipic acid An important use of adipoyl chloride is polymerization with an organic di amino compound to form a polyamide called nylon or polymerization with certain other organic compounds to form polyesters Phosgene carbonyl dichloride Cl CO Cl is a very toxic gas that is the dichloride of carbonic acid HO CO OH Both chloride radicals in phosgene can undergo reactions analogous to the preceding reactions of acyl halides Phosgene is used a reactant in the production of polycarbonate polymers among other industrial applications General hazards EditVolatile acyl halides are lachrymatory because they can react with water at the surface of the eye producing hydrohalic and organic acids irritating to the eye Similar problems can result if one inhales acyl halide vapors In general acyl halides even non volatile compounds such as tosyl chloride are irritants to the eyes skin and mucous membranes References Edit IUPAC Compendium of Chemical Terminology 2nd ed the Gold Book 1997 Online corrected version 2006 acyl groups doi 10 1351 goldbook A00123 IUPAC Compendium of Chemical Terminology 2nd ed the Gold Book 1997 Online corrected version 2006 acyl halides doi 10 1351 goldbook A00124 Saul Patai ed 1972 Acyl Halides PATAI S Chemistry of Functional Groups doi 10 1002 9780470771273 ISBN 9780470771273 Hosea Cheung Robin S Tanke G Paul Torrence Acetic Acid in Ullmann s Encyclopedia of Industrial Chemistry 2002 Wiley VCH Weinheim doi 10 1002 14356007 a01 045 Cheung Hosea Tanke Robin S Torrence G Paul 2000 Acetic Acid Ullmann s Encyclopedia of Industrial Chemistry Weinheim Wiley VCH doi 10 1002 14356007 a01 045 Helferich B Schaefer W 1929 n Butyrl chloride Organic Syntheses 9 32 doi 10 15227 orgsyn 009 0032 a b Allen C F H Barker W E 1932 Desoxybenzoin Organic Syntheses 12 16 doi 10 15227 orgsyn 012 0016 Maki Takao Takeda Kazuo 2000 Benzoic Acid and Derivatives Ullmann s Encyclopedia of Industrial Chemistry Weinheim Wiley VCH doi 10 1002 14356007 a03 555 Adams Roger 1923 p Nitrobenzoyl chloride Organic Syntheses 3 75 doi 10 15227 orgsyn 003 0075 Clarke H T Taylor E R 1929 o Chlorobenzoyl chloride Organic Syntheses 9 34 doi 10 15227 orgsyn 009 0034 Olah G Kuhn S 1961 Preparation of Acyl Fluorides with Anhydrous Hydrogen Fluoride The General Use of the Method of Colson and Fredenhagen J Org Chem 26 237 238 doi 10 1021 jo01060a600 Munoz Socrates B Dang Huong Ispizua Rodriguez Xanath Mathew Thomas Prakash G K Surya 2019 03 15 Direct Access to Acyl Fluorides from Carboxylic Acids Using a Phosphine Fluoride Deoxyfluorination Reagent System Organic Letters 21 6 1659 1663 doi 10 1021 acs orglett 9b00197 ISSN 1523 7060 PMID 30840474 S2CID 73481495 Keinan Ehud Sahai M June 1990 Diiodosilane 3 Direct synthesis of acyl iodides from carboxylic acids esters lactones acyl chlorides and anhydrides The Journal of Organic Chemistry 55 12 3922 3926 doi 10 1021 jo00299a042 ISSN 0022 3263 Allen C F H Kibler C J McLachlin D M Wilson C V 1946 Acid Anhydrides Organic Syntheses 26 1 3 doi 10 15227 orgsyn 026 0001 PMID 20280752 External links Edit Wikiquote has quotations related to Acyl halide Retrieved from https en wikipedia org w index php title Acyl halide amp oldid 1140319353, wikipedia, wiki, book, books, library,
