Anhydrous HCl Research Articles

Formation of an Unusual Guaiane Ketopentaenolide from Dehydroisoleucomisin by the Action of Anhydrous DMF and HCl

Dehydroisoleucomisin (anhydroaustricin) was converted in good yield to guai-1(10),3,5,7(11), 8-pentaen-2-on-12,8-olide by the action of anhydrous HCl in dry DMF. The chemical structure of the product was established using spectral data. The probable formation scheme of this lactone was proposed to include a series of prototopic transformations and ionic dehydrogenation of intermediates.

Synthesis of [Ni(η 2-CH 2C 6H 4R-4){PPh(CH 2CH 2PPh 2) 2}] + (R = H, Me or MeO) and protonation reactions with HCl

The complexes [Ni(η 2-CH 2C 6H 4R-4)(triphos)]BPh 4 {R = H, Me or MeO; triphos = PhP(CH 2CH 2PPh 2) 2} have been prepared and characterised by spectroscopy and X-ray crystallography. In all cases the coordination geometry of the nickel is best described as square-planar with an η 2-benzyl ligand occupying one of the positions. The orientation of the η 2-benzyl ligand is dictated by the steric restrictions imposed by the phenyl groups on the triphos ligand, so that the phenyl group on the unique secondary phosphorus and the aromatic group of the benzyl ligand (which are trans to one another) are oriented in the same direction. [Ni(η 2-CH 2C 6H 4R-4)(triphos)] + react with an excess of anhydrous HCl in MeCN to form [NiCl(triphos)] + (characterised as the [BPh 4] − salt by X-ray crystallography) and the corresponding substituted toluene. The kinetics of the reaction of all [Ni(η 2-CH 2C 6H 4R-4)(triphos)] + and HCl in the presence of Cl − have been determined using stopped-flow spectrophotometry. All reactions exhibit a first-order dependence on the concentration of complex and a first-order dependence on the ratio [HCl]/[Cl −]. Varying the 4-R-substituent on the benzyl ligand shows that electron-withdrawing substituents facilitate the rate of the reaction. It is proposed that the mechanism involves initial rapid protonation at the nickel to form [NiH(η 2-CH 2C 6H 4R-4)(triphos)] 2+, followed by intramolecular proton migration from nickel to carbon to yield the products.

Synthesis and Hydrolysis of a cis-Chlorohydrin Derived from a Benzo[a]pyrene 7,8-Diol 9,10-Epoxide

(+/-)-7beta,8alpha-Dihydroxy-9beta,10beta-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (DE-1) undergoes reaction with anhydrous HCl in dioxane to yield predominantly ( approximately 94%) a single chlorohydrin. This chlorohydrin was assigned structure 9, in which the chloro goup at C-10 is located cis to the C-9 hydroxyl group, on the basis of its (1)H NMR spectrum. This result is in contrast to the reaction of a diastereomeric benzo[a]pyrene 7,8-diol 9,10-epoxide (DE-2) with HCl, which yields only trans-chlorohydrin 8. The hydrolysis of cis-chlorohydrin 9 in 10:90 dioxane-water solutions yields the same ratio of tetrols ( approximately 89% cis/11% trans) as that formed by acid-catalyzed hydrolysis of DE-1. This result again contrasts with the hydrolysis of trans-chlorohydrin 8, which undergoes hydrolysis to give tetrols in a ratio different from that from acid-catalyzed hydrolysis of DE-2. A marked common ion rate depression in the hydrolysis of cis-chlorohydrin 9 is observed, which shows that hydrolysis proceeds via an intermediate carbocation that has a sufficient lifetime to be trapped by external chloride ion. The observation that DE-1 reacts with HCl to give mainly the cis-chlorohydrin is rationalized by quantum chemical calculations that suggest that the cis-chlorohydrin is more stable than the epimeric trans-chlorohydrin.

Chlorine Recovery from Anhydrous Hydrogen Chloride in a Molten Salt Electrolyte Membrane Cell.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Chlorine Recovery from Anhydrous Hydrogen Chloride in a Molten Salt Electrolyte Membrane Cell

A novel electrochemical membrane process has been developed to recover chlorine from anhydrous HCl waste. The proposed method produces a pure chlorine product stream and a hydrogen-enriched stream from HCl waste in a single step. The electrochemical method requires only an external electric potential and no concentration gradient, and it produces chlorine with exceptional selectivity. The electrolyzer can be operated at high current densities and current efficiencies. Downstream separation is not necessary, and no exotic electrode materials are required. A single experimental cell was constructed and tested for HCl removal and chlorine production from concentrated HCl reactant streams at variable flow rate. Applied current densities exceeded 400 mA/cm2, and conversions over 94% were achieved. Ohmic resistance dominated cell potentials due to the formation of hydrogen and chlorine bubbles. The proposed process is found to be a viable option for the treatment of anhydrous HCl waste. © 2003 The Electrochemical Society. All rights reserved.

The photolysis of dichlorotriphenylbismuth(V) in chloroform.

Under 254 nm irradiation in chloroform, Bi(C6H5)3Cl2 reacts to yield HBiCl4 and H2BiCl5, in contrast to its behavior in acetonitrile, in which bismuth metal appears to be the eventual product, unless anhydrous HCl is present, in which case H2BiCl5 is also formed. The photolysis in CHCl3 is not significantly solvent-initiated. The rate depends directly on the light intensity absorbed by the metal complex, and the quantum yield is 0.026. In CCl4 a portion of the reaction occurs through absorption of light by the solvent.

Exploring the coordination chemistry and reactivity of dialkylamino- and bis(dialkylamino)-phosphines in the coordination sphere of metals

The coordination chemistry of a range of dialkylamino- and bis(dialkylamino)-phosphines, RxP(NR′2)3 − x (x = 1 or 2; R = Cl, Me, Ph, C6F5; R′ = Et, Pri), 1–7, has been studied and the resulting Group 6 tetracarbonyl and platinum dichloride bis(phosphine) complexes fully characterised. Subsequently, the reactivity of the P–N bonds of the metal-bound phosphines was probed. Treatment of R″OH (R″ = Me, Et, allyl) solutions of the bis(dialkylaminodiphenylphosphine) complexes with anhydrous HCl gas led to substitution of NR′2 by OR″; the resulting P-alkoxy complexes were isolated in excellent yields. Acidification of ethylene glycol solutions of the aminophosphine complexes afforded the corresponding bis(chlorodiphenylphosphine) derivatives. Following reaction of trans-[W(CO)4(P{NEt2}Ph2)2] with either aqueous HCl or H2SO4, trans-[W(CO)4(P{OH}Ph2)2] could be isolated as its dichloromethane solvate in excellent yield (81%). Reactions of the bis(bis{dialkylamino}phenylphosphine) complexes under identical conditions yielded a range of unidentified products. Reactions of ligands 1–7 with [{RhCl(CO)2}2] and elemental selenium have been undertaken and the products used to assess the phosphines' donor capabilities. Depending on the substituents at phosphorus, either trans-diphosphine or cis-dicarbonyl complexes result from reaction with [{RhCl(CO)2}2]. The sterically demanding phosphine P(NPri2)2Ph (5) proved unreactive towards complexation with metals, although its selenide could be prepared and isolated. In order to probe the observed lack of oxidation or complexation the molecular structure P(NPri2)2(C6F5) has been determined by X-ray crystallography.

Chloride ion catalyzed conformational inversion of carbocation intermediates in the hydrolysis of a benzo[a]pyrene 7,8-diol 9,10-epoxide.

A highly efficient procedure for converting 7beta,8alpha-dihydroxy-9alpha,10alpha-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (1) to its trans-9,10-chlorohydrin (5) with excellent yield and purity by the reaction of anhydrous HCl in THF has been developed. The rate of reaction of 5 has been determined as a function of sodium chloride concentration in 1:1 dioxane-water solutions. A large common ion rate depression for the reaction of the chlorohydrin was observed, and the rate data are fit to a mechanism in which all of the tetrol products are formed by the reaction of water with the C-10 carbocation intermediate. Yet, the cis/trans ratio of tetrols from the reaction of the carbocation intermediate from the hydrolysis of chlorohydrin 5 is different than the cis/trans tetrol ratio from the acid-catalyzed hydrolysis of diol epoxide 1, which hydrolyzes via a carbocation with the same connectivity as that formed in the hydrolysis of 5. To rationalize these results, it is proposed that the S(N)1 reaction of chlorohydrin 5 yields a different distribution of carbocation conformations than that formed from the reaction of 1 with H(+). The energy barrier for the inversion of these carbocation conformations must be large relative to the energy barriers for the reaction of each carbocation conformation with water. In solutions containing sufficient concentrations of chloride ion, however, a lower energy pathway via a halohydrin exists for the interconversion of the carbocation conformations. Thus, chloride ion catalyzes the interconversion of these two carbocation conformations.

Water Transport in Polymer Electrolyte Membrane Electrolyzers Used to Recycle Anhydrous HCl : I. Characterization of Diffusion and Electro-osmotic Drag

In this paper, diffusion and electro-osmotic drag of water across Nafion® membranes in the presence of HCl are characterized. For all the measurements, one side of the Nafion membrane was in contact with liquid water and the other side with gaseous anhydrous HCl. To characterize diffusion of water, the open-circuit flux of water across a catalyst-coated Nafion 115 membrane was measured as a function of HCl flow rate and temperature at a constant cell pressure of 1 atm. Due to the nature of varying driving force for diffusion as a function of HCl flow rate, the experimental data was analyzed in conjunction with a mathematical model. The mathematical model accounts for condensation of water and is used to calculate the concentration of liquid hydrochloric acid in contact with the membrane. The mathematical model presented here is general and can be applied to the characterization of water transport across Nafion membranes in the presence of any gas that is soluble in water. In the case of HCl, at low inlet flow rates STP), the diffusion of water across the membrane is primarily governed by the diffusional limitations of HCl in the condensed phase. At high flow rates STP), the flux of water is a constant and depends on the saturation solubility of HCl in the condensed liquid phase. To measure the electro-osmotic drag parameter, the net flux of water across the membrane was measured as a function of the applied current density at high HCl flow rates (i.e., uniform water flux). At 80°C, it was found that 3.8 mol of water per mole of protons are transported from the anode to the cathode. © 2002 The Electrochemical Society. All rights reserved.

Kinetic studies on the reactions of HCl with trans-[MoL(CNPh)(Ph 2PCH 2CH 2PPh 2) 2] (L=N 2, H 2 or CO)

The kinetics of the reactions between anhydrous HCl and trans-[MoL(CNPh)(Ph 2PCH 2CH 2PPh 2) 2] (L=CO, N 2 or H 2) have been studied in thf at 25.0 °C. When L=CO, the product is [MoH(CO)(CNPh)(Ph 2PCH 2CH 2PPh 2) 2] +, and when L=H 2 or N 2 the product is trans-[MoCl(CNHPh)(Ph 2PCH 2CH 2PPh 2) 2]. Using stopped-flow spectrophotometry reveals that the protonation chemistry of trans-[MoL(CNPh)(Ph 2PCH 2CH 2PPh 2) 2] is complicated. It is proposed that in all cases protonation occurs initially at the nitrogen atom of the isonitrile ligand to form trans-[MoL(CNHPh)(Ph 2PCH 2CH 2PPh 2) 2] +. Only when L=N 2 is this single protonation sufficient to labilise L to dissociation, and subsequent binding of Cl − gives trans-[MoCl(CNHPh)(Ph 2PCH 2CH 2PPh 2) 2]. At high concentrations of HCl a second protonation occurs which inhibits the substitution. It is proposed that this second proton binds to the dinitrogen ligand. When L=CO or H 2, a second protonation is also observed but in these cases the second protonation is proposed to occur at the carbon atom of the aminocarbyne ligand, generating trans-[MoL(CHNHPh)(Ph 2PCH 2CH 2PPh 2) 2] 2+. Addition of the second proton labilises the trans-H 2 to dissociation, and subsequent rapid binding of Cl − and dissociation of a proton yields the product trans-[MoCl(CNHPh)(Ph 2PCH 2CH 2PPh 2) 2]. Dissociation of L=CO does not occur from trans-[Mo(CO)(CHNHPh)(Ph 2PCH 2CH 2PPh 2) 2] 2+, but rather migration of the proton from carbon to molybdenum, and dissociation of the other proton produces [MoH(CO)(CNPh)(Ph 2PCH 2CH 2PPh 2) 2] +.

Synthesis, structure, and reactions of a nitroxyl complex of iridium(III), cis,trans-IrHCl2(NH=O)(PPh3)2.

Reaction of Ir(NO)(PPh3)3 with anhydrous HCl results in addition of 2 equivalents of HCl with formal protonation of the nitrosyl ligand, affording the unusual six-co-ordinate nitroxyl complex cis,trans-IrHCl2(NH=O)(PPh3)2.

The interconversion of dichlorobis( N- n-propylsalicylaldimine)zinc(II) and bis( N- n-propylsalicylaldiminato)zinc(II)

The interconversion of the zinc(II) complex of the neutral ligand adduct of N- n-propylsalicylaldimine Zn(L prH) 2Cl 2 and its salicylaldiminato counterpart Zn(L pr) 2 is investigated. The compound Zn(L prH) 2Cl 2 is prepared by the reaction of anhydrous ZnCl 2 with 2 equiv. of N- n-propylsalicylaldimine (L prH) in benzene. A crystallographic study of the distorted tetrahedral Zn(L prH) 2Cl 2 adduct reveals that the oxygen atom of the ligand is deprotonated and bound to the zinc atom while the nitrogen is protonated and non-coordinating. An infrared spectrum of Zn(L prH) 2Cl 2 exhibits a CN stretch at a higher energy (1658 cm −1) than the free ligand (1632 cm −1) consistent with the presence of the iminium moiety. In contrast, the deprotonated ligand of the crystallographically characterized salicylaldiminato complex Zn(L pr) 2 coordinates to zinc in its prototypical bidentate monoanionic coordination mode. Deprotonation of Zn(L prH) 2Cl 2 with Et 3N or NaOH forms Zn(L pr) 2. The reverse reaction, protonation of Zn(L pr) 2 with anhydrous HCl, produces Zn(L prH) 2Cl 2. These reactions demonstrate the interrelationship between the zinc salicylaldimine adduct and its corresponding salicylaldiminato complex.

Anodic dissolution of silicon monocrystals in anhydrous organic solutions of chlorides

The electrochemical investigations of p- and n-silicon monocrystals were performed in anhydrous organic solutions of LiClO 4, LiCl and HCl to examine the possibility of etching and passivation of silicon semiconductors. The results obtained by means of linear sweep voltammetry (LSV), potentiostatic and galvanostatic transient technique, as well as XPS surface analysis allow us to give an explanation of the mechanism of silicon dissolution in these media. Silicon dissolves in anhydrous organic solvents (methanol, N, N-dimethyloformamide, formamide) which contain chloride ions according to the consecutive two-step mechanism. The Si(II) ad intermediate inhibits the anodic dissolution at low overpotentials. The presence of this intermediate was confirmed by means of XPS measurements on potentiostatically etched surface. The increase in chloride concentration in organic solvents stimulates desorption of the intermediate and therefore increases the rate of surface etching. The best results in anodic etching of silicon monocrystals have been obtained in anhydrous HCl solutions. Microscopic observations of surface morphology of Si monocrystals after etching show anisotropy of anodic dissolution.

Anion Stability in Stannylium, Oxonium, and Silylium Salts of the Weakly Coordinating Anion [C6F4-1,2-{B(C6F5)2}2(μ-OCH3)]-

Reaction of [Ph3C]+[C6F4-1,2-{B(C6F5)2}2(μ-OCH3)]-, 1, with Bu3SnH gives the solvated stannylium ion [Bu3Sn(arene)]+[C6F4-1,2-{B(C6F5)2}2(μ-OCH3)]-, 2, as a light brown oil (δ 119Sn = 434 ppm). This material is thermodynamically stable toward transfer of the chelated OMe- anion to “Bu3Sn+” as evidenced by the reaction of free diborane C6F4-1,2-[B(C6F5)2]2 with 2 equiv of Bu3SnOMe. This reaction produces the stannyloxonium complex [(Bu3Sn)2OCH3]+[C6F4-1,2-{B(C6F5)2}2(μ-OCH3)]-, 3 (δ 119Sn = 277 ppm), which is stable at −60 °C. Upon warming, the cation in 3 undergoes decomposition to unidentified products, while the anion remains intact. Ion pair 2 reacts rapidly with ethereal HCl in CH2Cl2 to generate Bu3SnCl and the oxonium acid [(Et2O)2H]+[C6F4-1,2-{B(C6F5)2}2(μ-OCH3)]-, 4, isolated in 76% yield as a white, crystalline solid. Acid 4 is thermally stable in solution and was characterized crystallographically. The C2B2OMe core of the anion in 4 deviates from planarity due to intermolecular interactions in the crystal, in contrast to the structures found in other ion pairs with this anion. Reaction of 2 with anhydrous HCl gives the unsymmetrical MeOH adduct of C6F4-1,2-[B(C6F5)2]2, 5, which was separately synthesized by direct reaction of methanol with the free diborane. The anion [C6F4-1,2-{B(C6F5)2}2(μ-OCH3)]- is not stable in the presence of the triethylsilylium ion, generated from 1 and Et3SiH.

Chemistry of coordinated nitroxyl. Reagent-specific protonations of trans-Re(CO)(2)(NO)(PR(3))(2) (R = Ph, Cy) that give the neutral nitroxyl complexes cis,trans-ReCl(CO)(2)(NH=O)(PR(3))(2) or the cationic hydride complex [trans,trans-ReH(CO)(2)(NO)(PPh(3))(2)(+)][SO(3)CF(3)(-)

The reactions of hydrochloric and triflic acids with the five-coordinate nitrosyl complexes trans-Re(CO)(2)(NO)(PR(3))(2) (2a, R = Ph; 2b, R = Cy) have been investigated. Reaction of anhydrous HCl with 2 results in a formal protonation of the nitrosyl ligand and addition of chloride to the metal, giving the neutral nitroxyl complex cis,trans-ReCl(CO)(2)(NH=O)(PR(3))(2) (3a, R = Ph; 3b, R = Cy). Reaction of Brønsted bases with 3a or 3b results in clean conversion of 3 to 2 when the base is appropriately strong (pK(b) approximately 7). Addition of HOSO(2)CF(3) to solutions of 2a results in protonation at the metal and formation of the cationic rhenium hydride [trans,trans-ReH(CO)(2)(NO)(PPh(3))(2)(+)][SO(3)CF(3)(-)] (4) in 74% yield; the deuteride [trans,trans-Re((2)H)(CO)(2)(NO)(PPh(3))(2)(+)][SO(3)CF(3)(-)] (4-d) was analogously prepared from (2)HOSO(2)CF(3). 4 crystallized from CH(2)Cl(2)/Et(2)O solution in the orthorhombic space group Pnma, with a = 17.2201(2) A, b = 23.6119(3) A, c = 9.2380(2) A, and Z = 4. The least-squares refinement converged to R(F) = 0.039 and R(wF(2)()) = 0.063 for the 4330 unique data with I > 2 sigma(I). The structure of 4 shows that the hydride (Re-H = 1.74 A) occupies the position trans to the linear nitrosyl ligand (Re-N-O = 178.1(4) degrees ) in the pseudooctahedral complex cation. Complex 4 does not react with chloride to give 3a. DFT calculations carried out on free nitroxyl and its model complexes [Re(CO)(5)(NH=O)(+)] (5), [mer,trans-Re(CO)(3)(NH=O)(PH(3))(2)(+)] (6), and cis,trans-ReCl(CO)(2)(NH=O)(PH(3))(2) (7) indicate that coordinated nitroxyl acts as both a sigma-donor and pi-acceptor ligand, consistent with the observed trend for nu(NO) in free HN=O (1563 cm(-1)), [mer,trans-Re(CO)(3)(NH=O)(PPh(3))(2)(+)] (1, 1391 cm(-1)), 3a (1376 cm(-1)), and 3b (1335 cm(-1)).

Synthesis, characterization and reactivity of ReOMe 2(bipy)X complexes

The complexes cis- and trans-ReOMe 2(bipy)Cl, where cis or trans refers to the Me–Re–Me regiochemistry, were observed to react as follows: (1) with the alkylating agents RMgCl (R=CH 2SiMe 3 and CH 2Ph) and RLi (R=Me) to give ReOMe 2(bipy)R, and (2) with the alkoxides NaOR′ (R′=Me and Et) to give trans-ReOMe 2(bipy)(OR′). The complex ReOMe 2(bipy)CH 2SiMe 3 was observed by 1H NMR spectroscopy to undergo trans to cis isomerization, which proceeded via reversible first-order kinetics, with Δ H°=1.60(4) kcal mol −1 and Δ S°=3.7(1) eu. At room temperature, Δ G°=0.5(1) kcal mol −1 and K eq=0.42(2), indicating a weak thermodynamic preference for the trans isomer. The activation parameters for the trans to cis isomerization were Δ H ‡ 1=26(2) kcal mol− 1 and Δ S ‡ 1=10(7) eu, and those for the reverse cis to trans isomerization were Δ H ‡ −1=27(2) kcal mol −1 and Δ S ‡ −1=14(7) eu. Treatment of a mixture of cis- and trans-ReOMe 2(bipy)CH 2SiMe 3 with anhydrous HCl gave ReOMe(bipy)(CH 2SiMe 3)Cl; similar treatment of ReOMe 3(bipy) and ReOMe 2(bipy)CH 2Ph gave cis-ReOMe 2(bipy)Cl. Exposure of ReOMe(bipy)(CH 2SiMe 3)Cl to AgPF 6 in acetonitrile-d 3 gave the cationic nitrile adduct [ReOMe(bipy)(CH 2SiMe 3)(CD 3CN)][PF 6].

A novel protonated boranoamino acid amide derivative, (CH 3) 3N·BH 2C(OH)N +HC 2H 5Cl −: A synthetic and structural investigation

The reaction between Me 3N·BH 2CONHC 2H 5 ( 1) and anhydrous HCl gas in diethyl ether resulted in the formation of an unprecedented salt, Me 3N·BH 2C(OH)N +HC 2H 5Cl − ( 2), whose crystal structure unambiguously shows that the amide hydrogen atom is oriented in trans configuration with respect to the hydroxyl group.

Use of methanolysis for the determination of total ellagic and gallic acid contents of wood and food products.

Anhydrous methanolic HCl has been found to be an excellent reagent for releasing ellagic acid and gallic acid (as methyl gallate) from biomass substrates. Optimization of both the reaction conditions and the gradient HPLC analysis has led to the development of a new protocol. The method provides ellagic acid yields significantly higher than those obtained previously, indicating total ellagic acid contents of several substrates have previously been underestimated.

Oxo complexes of osmium(IV) formed via dioxygen activation. X-ray structures of [OsX(dcpe)2]PF6 (X = Cl, Br), [OsCl(eta 2-O2)(dcpe)2]BPh4, and [OsCl(O)(dcpe)2]BPh4 (dcpe = 1,2-bis(dicyclohexylphosphino)ethane).

Dioxygen addition to the 16-electron complexes [OsX(P-P)2]+ (3) gives the dioxygen adducts [OsCl(eta 2-O2)(P-P)2]+ (3), which in turn react with HCl gas to give the novel osmium(IV) oxo complexes trans-[OsX(O)(P-P)2]+ (5) (X = Cl, Br; P-P = 1,2-bis(dicyclohexylphosphino)ethane (dcpe), 1,2-bis(diethylphosphino)ethane (depe), 1,2-bis((2R,5R)-2,5-dimethylphospholano)benzene (Me-duphos)). The complexes [OsX(dcpe)2]+ (X = Cl, Br) (3) are studied by X-ray crystallography and are shown to have a "Y-shaped" coordination geometry in the equatorial plane. The X-ray structural analysis of [OsCl(eta 2-O2)(dcpe)2]+ (4a) reveals an exceptionally short O-O bond (1.315(5) A). trans-[OsCl(O)(dcpe)2]+ (5a), the first oxo complex of osmium(IV) investigated crystallographically, exhibits a long Os-O distance of 1.834(3) A. The reactivity of 4 and 5 as oxidants is described. The dioxygen complex 4a transfers one oxygen atom to PPh3 (to give Ph3PO) or oxidizes iodide ions to triiodide ions in the presence of anhydrous HCl. In both reactions, the corresponding oxo species 5a is quantitatively formed as the only metal-containing product. Oxo complexes 5 are surprisingly stable and unreactive toward standard reducing agents such as phosphines.

Failure analysis of an HCl gas cylinder valve

The fouling failure of an anhydrous HCl gas cylinder valve was investigated after the failure led to an accidental release of HCl gas. It is surmised that water penetrated into the valve by improper purging or valving, and created a severely corrosive environment. The aluminum bronze valve body underwent general corrosion. The corrosion products, primarily nantokite (CuCl), built up within the valve and led to the fouling failure. Dezincification was observed in a leaded nickel silver component of the valve. The Monel 400 valve stem was intact. The cylinder and valve testing procedures that led to the gas release incident are also examined.