Oxalyl chloride

On treatment with copper acetate a small quantity of a tarry precipitate forms. Ferric chloride gives no colouration with dichloroformoxime, unlike chloroformoxime. 

Dichloroformoxime, even when stored in sealed vessels of glass or quartz, decomposes at ordinary temperatures with formation of phosgene and separation of a liquid compound. The decomposition is practically complete in 3-4 weeks, but is influenced by humidity and temperature. The vapour of dichloroformoxime attacks rubber and cork. 

It has a violently irritant action on the mucous membrane of the nose and on the eyes. The vapour of this substance, even in very low concentrations, provokes lachrymation. 

When it comes into contact with the skin it produces inflammation and blisters, which can be prevented by treating the affected part immediately with plenty of aqueous ammonia (Prandtl). 

Oxalyl chloride was prepared by Fauconnier in 1892 by heating ethyl oxalate with phosphorus pentachloride. The product obtained in this way, however, is impure with phosphorus oxychloride. 

Anhydrous oxalic acid (90 g., 1.0 mole) is finely ground and thoroughly mixed with 400 g. (1.92 moles) of powdered phosphorus penta-chloride. (Hood.) The mixture is allowed to stand first in an ice bath then at room temperature for 2-3 days until the mass is com- 

Solubility sol hexane, benzene, diethyl ether, halogenated solvents, e.g. dichloromethane and chloroform, acetonitrile. 

Form Supplied in colorless, fuming liquid widely available 2 M soln in dichloromethane. 

Preparation of Carboxylic Acid Chlorides (and Anhydrides). Oxalyl chloride has found general application for the preparation of carboxylic acid chlorides since the reagent was introduced by Adams and Ulich. Acid chlorides produced by this means have subsequently featured in the synthesis of acyl azides, bromoalkenes, carboxamides, cinnolines, diazo ketones, (thio)esters, lactones, ketenes for cycloaddition reactions, intramolecular Friedel-Crafts acylation reactions, and the synthesis of pyridyl thioethers.  

Like Thionyl Chloride, oxalyl chloride gives gaseous byproducts with acids and the chlorides can be readily isolated in a pure form by evaporation of the solvent and any excess reagent, or used in situ for further elaboration (eq 1). 

The use of nonpolar solvents such as hexane or toluene allows for the removal of inorganic or amine salts which may otherwise interfere with subsequent reactions. 

Colorless fuming liquid with penetrating odor bp, 63-64°C.  

Reacts vigorously with water forming hydrochloric and oxalic acids.2 

Potassium and Potassium-Sodium. Mixtures are shock sensitive and explode very violently.2,3 

Vapor severely irritates the respiratory system and eyes. Liquid irritates eyes and skin and may cause burns. Assumed to be very irritating and poisonous if swallowed. Avoid breathing vapor. Prevent contact with skin and eyes.2 

Wear nitrile rubber gloves, laboratory coat, eye protection and, if necessary, a self-contained breathing apparatus. Cover the spill with a 1 1 1 mixture by weight of sodium carbonate or calcium carbonate, clay cat litter (bentonite), and sand. When the oxalyl chloride has been absorbed, scoop the mixture into a plastic pail and, in the fume hood, very slowly add the mixture to a pail of cold water. Allow it to stand for 24 hours. Test the pH of the solution and neutralize if necessary with sodium carbonate. Decant the solution to the drain flushing with 50 times its volume of water. Treat the solid residue as normal refuse.2,4 

Prior formation of an amine or alkali metal salt, with or without pyridine, has been used to advantage with substrates that are sensitive to strong acids or are bases (see also Oxalyl Chloride-Dimethylformamide for a procedure conducted under neutral conditions using silyl esters). By adjusting the molar proportions of oxalyl chloride to substrate, anhydrides can also be 

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The reaction giving A is chloromethylation, a reliable metliod of adding a CH2OH equivalent to an aromatic ring. You may have been surprised at the use of reagent B to make an acid chloride. B is oxalyl chloride and is often used when pure acid chlorides are wanted - the other products are gases (which ). 

Oxalyl chloride reacts at 25°Cin tetrahydrofuran with 2-amino-5-nitro-thiazole. yielding structure 98 (Scheme 68) (261). 

Preparation of Arylcarboxylic Acids and Derivatives. The general Friedel-Crafts acylation principle can be successfully appHed to the preparation of aromatic carboxyUc acids. Carbonyl haUdes (phosgene, carbonyl chloride fluoride, or carbonyl fluoride) [353-50-4] are diacyl haUdes of carbonic acid. Phosgene [75-44-5] or oxalyl chloride [79-37-8] react with aromatic hydrocarbons to give aroyl chlorides that yield acids on hydrolysis (133) ... 

Acylation. Acylation is the most rehable means of introducing a 3-substituent on the indole ring. Because 3-acyl substituents can be easily reduced to 3-aLkyl groups, a two-step acylation—reduction sequence is often an attractive alternative to direct 3-aLkylation. Several kinds of conditions have been employed for acylation. Very reactive acyl haUdes, such as oxalyl chloride, can effect substitution directiy without any catalyst. Normal acid chlorides are usually allowed to react with the magnesium (15) or 2inc (16) salts. The Vilsmeier-Haack conditions involving an amide and phosphoms oxychloride, in which a chloroiminium ion is the active electrophile, frequentiy give excellent yields of 3-acylindoles. 

Specialty Isocyanates. Acyl isocyanates, extensively used in synthetic appHcations, caimot be direcdy synthesized from amides and phosgene. Reactions of acid haUdes with cyanates have been suggested. However, the dominant commercial process utilizes the reaction of carboxamides with oxalyl chloride [79-37-8]. CycHc intermediates have been observed in these reactions which generally give a high yield of the desired products (86). 

Commercially important arenesulfonyl isocyanates are not directly accessible from the corresponding sulfonamides via phosgenation due to lack of reactivity or by-product formation at elevated temperatures. A convenient method for their preparation consists of the reaction of alkyl isocyanates with sulfonamides to produce mixed ureas which, upon phosgenation, yield a mixture of alkyl and arenesulfonyl isocyanates. The desired product can be obtained by simple distillation (16). Optionally, the oxalyl chloride route has been employed for the synthesis of arenesulfonyl isocyanate (87). 

Oxahc acid reacts with various metals to form metal salts, which are quite important as the derivatives of oxahc acid. It also reacts easily with alcohols to give esters. Crystalline dimethyl oxalate is, for example, produced by the reaction of oxahc acid dihydrate and methanol under reflux for a few hours. When oxahc acid is treated with phosphoms pentachloride, oxalyl chloride, ClCOCOCl, is formed (6). 

Oxalyl Chloride. This diacid chloride [79-37-8], ClCOCOCl, mol wt 126.9, is produced by the reaction of anhydrous oxaUc acid and phosphoms pentachloride. The compound vigorously reacts with water, alcohols, and amines, and is employed for the synthesis of agrochemicals, pharmaceuticals, and fine chemicals. 

Sorbic acid anhydride [13390-06-2] can be prepared by heating the polyester of 3-hydroxy-4-hexenoic acid with sorboyl chloride [2614-88-2] or by reaction of sorbic acid with oxalyl chloride (15,16). Preparation of the esters of sorbic acid must be controlled to prevent oxidation and polymerization. The lower sorbic acid esters have a pleasant odor. 

Cl Vat YeUow 12 is prepared by condensing l-anaino-5-ben2oylaininoanthraquinone [117-06-6] (161) with oxalyl chloride in nitroben2ene. Cl Vat YeUow 33 is prepared by condensation of two moles of 1-aminoanthraquinone with one mole of 4V -a2obis(4-biphenylcarbonyl chloride). Cl Vat Red 21 is prepared from 1,4-diaminoanthraquinone (33) and l-nitroanthraquinone-2-carboxyhc acid (58) by the foUowing process ... 

Because of the structural requirements of the bielectrophile, fully aromatized heterocycles are usually not readily available by this procedure. The dithiocarbamate (159) reacted with oxalyl chloride to give the substituted thiazolidine-4,5-dione (160) (see Chapter 4.19), and the same reagent reacted with iV-alkylbenzamidine (161) at 100-140 °C to give the 1 -alkyl-2-phenylimidazole-4,5-dione (162) (see Chapter 4.08). Iminochlorides of oxalic acid also react with iV,iV-disubstituted thioureas in this case the 2-dialkylaminothiazolidine-2,4-dione bis-imides are obtained. Thiobenzamide generally forms linear adducts, but 2-thiazolines will form under suitable conditions (70TL3781). Phenyliminooxalic acid dichloride, prepared from oxalic acid, phosphorus pentachloride and aniline in benzene, likewise yielded thiazolidine derivatives on reaction with thioureas (71KGS471). 

Of particular interest is the reaction of 5,5-disubstituted sulfur diimides (188) with oxalyl chloride in dilute solution in the presence of triethylamine. The l,2,5-thiadiazole-3,5-dione (189) was formed in almost quantitative yield (72LA(759)107). 

The aziridinecarboxylate (177) undergoes ring expansion in good yield, possibly via a mixed anhydride, on treatment with thionyl or oxalyl chlorides in benzene (69JA4590). 

Pivaloyl chloride (trimethylacetyl chloride) [3282-30-2] M 120.6, b 57.6"/150mm, 70.5-71/250mm, 104"/754mm, 104-105"/atm, 105-108"/atm, d 1.003, n p 1.4142. First check the IR to see if OH hands are present. If absent, or present in small amounts, then redistil under moderate vac. If present in large amounts then treat with oxalyl chloride or thionyl chloride and reflux for 2-3h, evap and distil residue. Strongly LACHRYMATORY - work in a fumecupboard. Store in sealed ampoules under N2. [Traynham and Battiste J Org Chem 22 1551 1957, Grignard reactns Whitmore et al. J Am Chem Soc 63 647 1941.]... 

The mildness of oxalyl chloride permits other sensitive hydroxyl groups ie.g., 5 -OH) to survive without protection. Even the 11 -hydroxyl group has a moderate degree of stability to this reagent. ... 

Depending on the reagent ratio, oxalyl chloride reacts with fluorobenzene m the presence of aluminum chloride to afford either 4-fluorobenzoyl chloride or 4,4 -difluorobenzophenone [ii] (equation 22). Phosgene, detected by infrared spectroscopy, is an intermediate. 

A more practical solution to this problem was reported by Larson, in which the amide substrate 20 was treated with oxalyl chloride to afford a 2-chlorooxazolidine-4,5-dione 23. Reaction of this substrate with FeCL affords a reactive A-acyl iminium ion intermediate 24, which undergoes an intramolecular electrophilic aromatic substitution reaction to provide 25. Deprotection of 25 with acidic methanol affords the desired dihydroisoquinoline products 22. This strategy avoids the problematic nitrilium ion intermediate, and provides generally good yields of 3-aryl dihydroisoquinolines. 

The related compounds bis(2-mothyl-3-indolyl)glyoxal (263) and bis(3-methyl-l-indolyl)glyoxai (264) - have been prepared by the action of oxalyl chloride on the Grignard reagents derived from 2-methylindole and 3-methylindole, respectively, Eis(l-methyl-3-indolyl)-glyoxal (265) was prepared by the action of oxalyl chloride on 1-methyIindole in ether. 

The early literature on the reactions of the indole Grignard reagents with the simple diacid chlorides, in particular with carbonyl chloride and oxalyl chloride (see Section III,C,4,b), is both conflicting and confusing and much of the work reported warrants repetition since the evidence presented in support of many of the structural assignments made is not entirel3 convincing. 

The ready access to compound 204 also provided efficient routes to additional monosubstituted indolo[3,2-()]carba2oles, as reaction with ethyl oxalyl chloride... 

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