Phosphorous oxychlorides

The important chemical properties of acetyl chloride, CH COCl, were described ia the 1850s (10). Acetyl chloride was prepared by distilling a mixture of anhydrous sodium acetate [127-09-3J, C2H202Na, and phosphorous oxychloride [10025-87-3] POCl, and used it to interact with acetic acid yielding acetic anhydride. Acetyl chloride s violent reaction with water has been used to model Hquid-phase reactions. 

Jicyylic anhydride is formed by treatment of the acid with acetic anhydride or by reaction of acrylate salts with acryloyl chloride. Jicryloylchloride is made by reaction of acryhc acid with phosphorous oxychloride, or benzoyl or thionyl chloride. Neither the anhydride nor the acid chloride is of commercial interest. 

Phosphorus compounds (phosphoric acid, phosphorous pentoxide, phosphorous oxychloride, phosphorous pentachloride, phosphorous pentasulphide)... 

One of the most widely used systems for dehydration is the combination of phosphorous oxychloride and pyridine. This reagent is apparently incompatible with the A" -3-keto system/ probably due to formation of a phosphorylated enol. It is, however, more selective than thionyl chloride-pyridine since 17a-alcohols are not dehydrated ... 

It has generally been assumed that phosphorous oxychloride-pyridine dehydrations, the elimination of sulfonates, and other base catalyzed eliminations (see below) proceed by an E2 mechanism (see e.g. ref. 214, 215, 216). Concerted base catalyzed eliminations in acyclic systems follow the Saytzelf orientation rule i.e., proceed toward the most substituted carbon), as do eliminations (see ref 214). However, the best geometrical arrangement of the four centers involved in 2 eliminations is anti-coplanar and in the cyclohexane system only the tran -diaxial situation provides this. 

When, in the phosphorous oxychloride-pyridine dehydration of an alcohol these rules conflict, the stereoelectronic factor determines the direction of elimination ... 

Thionyl chloride behaves in some circumstances as though it dehydrates by tran -diaxial elimination, as described for phosphorous oxychloride. For example, the 5a-alcohol (102) undergoes anti-Saytzelf elimination to give the A" -olefin. In this particular example, phosphorous oxychloride-pyridine does not work, and acetic anhydride-sulfuric acid gives the A -isomer (ref. 185, p. 199). 

Tetrahydropyranyl ethers are prepared by reaction with 2,3-dihydropyran, and a catalyst such as hydrochloric acid, " phosphorous oxychloride or p-toluenesulfonic acid at room temperature. 3iS-Hydroxy-5-enes " also form pyranyl ethers by distillation of a solution of the steroid and dihy-dropyran in ether without a catalyst. 

Preparation of the oxime presents no problem, since there is little tendency for hydroxylamine to add to the double bond of the unsaturated system. A variety of acid catalysts has been used e.g., POCI3, BF3, p-ACNHC6H4SO2CI) to effect the rearrangement, and phosphorous oxychloride is the usual choice. 

Phosphorous oxychloride Phosphorous pentachloride Phosphorous trichloride... 

The isoquinoline framwork is derived from the corresponding acyl derivatives of P-hydroxy-P phenylethylamines. Upon exposure to a dehydrating agent such as phosphorous pentaoxide, or phosphorous oxychloride, under reflux conditions and in an inert solvent such as decalin, isoquinoline frameworks are formed. 

Substituents in the 6-position (cf. 267) show appreciable reactivity. 6-Bromo-as-triazine-3,5(2j, 4j )-dione (316) undergoes 6-substitution with secondary amines or hydrazine, with mercaptide anions or thiourea (78°, 16 hr), with molten ammonium acetate (170°, 24 hr, 53% yield), and with chloride ion during phosphorous oxychloride treatment to form 3,5,6-trichloro-as-triazine. The latter was characterized as the chloro analog of 316 by treatment with methanol (20°, heat evolution) and hydrolysis (neutral or acid) to the dioxo compound. The mercapto substituent in 6-mercapto-as-triazine-3,5(2iI,4if)-dione is displaced by secondary... 

Cresylic acid is mainly used as degreasing agent and as a disinfectant of a stabilized emulsion in a soap solution. Cresols are used as flotation agents and as wire enamel solvents. Tricresyl phosphates are produced from a mixture of cresols and phosphorous oxychloride. The esters are plasticizers for vinyl chloride polymers. They are also gasoline additives for reducing carbon deposits in the combustion chamber. 

O-isopropylidene derivative (10) was then phosphorylated with phosphorous oxychloride to form the phosphate ester (11) from which the protecting groups were removed by mild acid hydrolysis. The 3-phos-phate (15) was obtained by phosphorylating the 4,6-benzylidene derivative (13) of the same glycoside with phosphorus oxychloride, followed by hydrolytic removal of the protecting groups, from the ester (14) thus obtained. 

The synthesis of key intermediate 12, in optically active form, commences with the resolution of racemic trans-2,3-epoxybutyric acid (27), a substance readily obtained by epoxidation of crotonic acid (26) (see Scheme 5). Treatment of racemic 27 with enantio-merically pure (S)-(-)-1 -a-napthylethylamine affords a 1 1 mixture of diastereomeric ammonium salts which can be resolved by recrystallization from absolute ethanol. Acidification of the resolved diastereomeric ammonium salts with methanesulfonic acid and extraction furnishes both epoxy acid enantiomers in eantiomerically pure form. Because the optical rotation and absolute configuration of one of the antipodes was known, the identity of enantiomerically pure epoxy acid, (+)-27, with the absolute configuration required for a synthesis of erythronolide B, could be confirmed. Sequential treatment of (+)-27 with ethyl chloroformate, excess sodium boro-hydride, and 2-methoxypropene with a trace of phosphorous oxychloride affords protected intermediate 28 in an overall yield of 76%. The action of ethyl chloroformate on carboxylic acid (+)-27 affords a mixed carbonic anhydride which is subsequently reduced by sodium borohydride to a primary alcohol. Protection of the primary hydroxyl group in the form of a mixed ketal is achieved easily with 2-methoxypropene and a catalytic amount of phosphorous oxychloride. 

The checkers obtained an identical result when the molar ratio of phosphorous oxychloride to substrate was reduced from 2.35 to 1.5. 

NC13, mw 120.38, N 11.64% yel, vol, pungent-smelling oil, mp <-40° (Porret in 1813 reported —27°), bp about 71° (explds at 93-95°), d 1.653g/cc. Sol in cold w (decompd by hot w), ale, eth, chlf, bz, CCl CS2 phosphorous oxychloride. Prepd (with great care) by the action of sodium hypochlorite on amm chloride. The compd also forms at the anode in the electrolysis of coned amm chioride soln. Another prepn consists of bubbling chlorine into a cooled aq soln of amm sulfate di-n-butyl ether (Refs 1,... 

Among the many applications of cyclodehydration to the formation of heterocyclic systems is the Bischler-Napieralski reaction. In this reaction, amides of the type 35 are cyclized with phosphorous oxychloride ... 

Reaction of 256 with phosphorous oxychloride and DMF involves first formylation at the 6-position opening of the ketal to the enol ether by the HC1 produced in the Vilsmeier reaction would afford a hydroxyethyl side chain at C-3. This is no doubt converted to a chloroethyl group by excess oxychloride. There is thus obtained the antiinflammatory agent formocortal (257). 77... 

The reaction was repeated using one half the quantity of phosphorous oxychloride (equivalent to the estimated number of OH groups in the polymer). The intrinsic viscosity increased from 0.33 to 0.70 dl/g and the OH absorbance at 3610 cm decreased from 0.18 to 0.015. 

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