ثلاثي كلوريد الفسفور

Phosphorus trichloride

الأسماء
اسم أيوپاك Phosphorus trichloride
اسم أيوپاك النظامي Trichlorophosphane
أسماء أخرى Phosphorus(III) chloride Phosphorous chloride
Identifiers
رقم CAS
3D model (JSmol)	Interactive image
ChEBI	CHEBI:30334 Y
ChemSpider	22798 Y
ECHA InfoCard	100.028.864
رقم EC	231-749-3
PubChem CID	24387
رقم RTECS	TH3675000
UNII	M97C0A6S8U N
UN number	1809
CompTox Dashboard (EPA)	DTXSID5029687
InChI	InChI={{{value}}}
SMILES
الخصائص
الصيغة الجزيئية	PCl3
كتلة مولية	137.33 g/mol
المظهر	Colorless to yellow fuming liquid
الرائحة	unpleasant, acrid, like hydrochloric acid
الكثافة	1.574 g/cm3
نقطة الانصهار
نقطة الغليان
قابلية الذوبان في الماء	hydrolyzes
قابلية الذوبان في other solvents	soluble in benzene, CS2, ether, chloroform, CCl4, halogenated organic solvents reacts with ethanol
ضغط البخار	13.3 kPa
القابلية المغناطيسية	−63.4·10−6 cm3/mol
معامل الانكسار (nD)	1.5122 (21 °C)
اللزوجة	0.65 cP (0 °C) 0.438 cP (50 °C)
Dipole moment	0.97 D
الكيمياء الحرارية
الإنتالپية المعيارية للتشكل ΔfHo298	−319.7 kJ/mol
المخاطر
خطر رئيسي	Highly toxic, corrosive
صفحة بيانات السلامة	ICSC 0696
ن.م.ع. مخطط تصويري
ن.م.ع. كلمة الاشارة	Danger
ن.م.ع. عبارات المخاطر	H300, H301, H314, H330, H373
ن.م.ع. العبارات الاحتياطية	P260, P273, P284, P303+P361+P353, P304+P340+P310, P305+P351+P338
NFPA 704 (معيـَّن النار)	0 4 2 W
الجرعة أو التركيز القاتل (LD, LC):
LD50 (الجرعة الوسطى)	18 mg/kg (rat, oral)
LC50 (التركيز الأوسط)	104 ppm (rat, 4 hr) 50 ppm (guinea pig, 4 hr)
حدود التعرض الصحية بالولايات المتحدة (NIOSH):
PEL (المسموح)	TWA 0.5 ppm (3 mg/m3)
REL (الموصى به)	TWA 0.2 ppm (1.5 mg/m3) ST 0.5 ppm (3 mg/m3)
IDLH (خطر عاجل)	25 ppm
مركبات ذا علاقة
phosphorus chlorides ذات العلاقة	Phosphorus pentachloride Phosphorus oxychloride Diphosphorus tetrachloride
مركـّبات ذات علاقة	Phosphorus trifluoride Phosphorus tribromide Phosphorus triiodide
ما لم يُذكر غير ذلك، البيانات المعطاة للمواد في حالاتهم العيارية (عند 25 °س [77 °ف]، 100 kPa).
N verify (what is YN ?)
مراجع الجدول

Phosphorus trichloride is an inorganic compound with the chemical formula PCl₃. A colorless liquid when pure, it is an important industrial chemical, being used for the manufacture of phosphites and other organophosphorus compounds. It is toxic and reacts readily with water to release hydrogen chloride.

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 History

Phosphorus trichloride was first prepared in 1808 by the French chemists Joseph Louis Gay-Lussac and Louis Jacques Thénard by heating calomel (Hg₂Cl₂) with phosphorus. Later during the same year, the English chemist Humphry Davy produced phosphorus trichloride by burning phosphorus in chlorine gas.

 Preparation

World production exceeds one-third of a million tonnes. Phosphorus trichloride is prepared industrially by the reaction of chlorine with white phosphorus, using phosphorus trichloride as the solvent. In this continuous process PCl₃ is removed as it is formed in order to avoid the formation of PCl₅.

P₄ + 6 Cl₂ → 4 PCl₃

 Structure and spectroscopy

It has a trigonal pyramidal shape. Its ³¹P NMR spectrum exhibits a singlet around +220 ppm with reference to a phosphoric acid standard.^{[بحاجة لمصدر]}

 Reactions

The phosphorus in PCl₃ is often considered to have the +3 oxidation state and the chlorine atoms are considered to be in the −1 oxidation state. Most of its reactivity is consistent with this description.

 Oxidation

PCl₃ is a precursor to other phosphorus compounds, undergoing oxidation to phosphorus pentachloride (PCl₅), thiophosphoryl chloride (PSCl₃), or phosphorus oxychloride (POCl₃).

 PCl₃ as an electrophile

PCl₃ reacts vigorously with water to form phosphorous acid (H₃PO₃) and hydrochloric acid:

PCl₃ + 3 H₂O → H₃PO₃ + 3 HCl

Phosphorus trichloride is the precursor to organophosphorus compounds. It reacts with phenol to give triphenyl phosphite:

3 PhOH + PCl
3 → P(OPh)
3 + 3 HCl (Ph = C
6H
5)

Alcohols such as ethanol react similarly in the presence of a base such as a tertiary amine:

PCl
3 + 3 EtOH + 3 R
₃N → P(OEt)
3 + 3 R
3NH⁺Cl⁻

With one equivalent of alcohol and in the absence of base, the first product is alkoxyphosphorodichloridite:

PCl
3 + EtOH → PCl
2(OEt) + HCl

In the absence of base, however, with excess alcohol, phosphorus trichloride converts to diethylphosphite:

PCl₃ + 3 EtOH → (EtO)₂P(O)H + 2 HCl + EtCl

Secondary amines (R₂NH) form aminophosphines. For example, bis(diethylamino)chlorophosphine, (Et₂N)₂PCl, is obtained from diethylamine and PCl₃. Thiols (RSH) form P(SR)₃. An industrially relevant reaction of PCl₃ with amines is phosphonomethylation, which employs formaldehyde:

R₂NH + PCl₃ + CH₂O → (HO)₂P(O)CH₂NR₂ + 3 HCl

The herbicide glyphosate is also produced this way.

The reaction of PCl₃ with Grignard reagents and organolithium reagents is a useful method for the preparation of organic phosphines with the formula R₃P (sometimes called phosphanes) such as triphenylphosphine, Ph₃P.

3 RMgBr + PCl
3 → R
3P + 3 MgBrCl

Triphenylphosphine is produced industrially by the reaction between phosphorus trichlorid, chlorobenzene, and sodium:

PCl
3 + 3 PhCl + 6 Na → PPh
3 + 6 NaCl, where Ph = C
6H
5

Under controlled conditions or especially with bulky R groups, similar reactions afford less substituted derivatives such as chlorodiisopropylphosphine.

 Conversion of alcohols to alkyl chlorides

Phosphorus trichloride is commonly used to convert primary and secondary alcohols to the corresponding chlorides. As discussed above, the reaction of alcohols with phosphorus trichloride is sensitive to conditions. The mechanism for the ROH →RCl conversion involves the reaction of HCl with phosphite esters:

P(OR)
3 + HCl ⇌ HP(OR)+
3Cl⁻

HP(OR)+
3Cl⁻ → RCl + HOP(OR)
2.

HOP(OR)
2 + HCl ⇌ H
2OP(OR)+
2Cl⁻

H
2OP(OR)+
2Cl⁻ → RCl + (HO)
2P(OR)

(HO)
2P(OR) + HCl ⇌ H(HO)
2P(OR)⁺Cl⁻

H(HO)
2P(OR)⁺Cl⁻ → RCl + (HO)
3P

The first step proceeds with nearly ideal stereochemistry but the final step far less so owing to an SN2 pathway.

 Redox reactions

Phosphorus trichloride undergoes a variety of redox reactions:

3PCl
3 + 2 CrO
3 → 3POCl
3 + Cr
2O
3

PCl
3 + SO
3 → POCl
3 + SO
2

3 PCl
3 + SO
2 → 2POCl
3 + PSCl
3

 PCl₃ as a nucleophile

Phosphorus trichloride has a lone pair, and therefore can act as a Lewis base, e.g., forming a 1:1 adduct Br₃B-PCl₃. Metal complexes such as Ni(PCl₃)₄ are known, again demonstrating the ligand properties of PCl₃.

This Lewis basicity is exploited in the Kinnear–Perren reaction to prepare alkylphosphonyl dichlorides (RP(O)Cl₂) and alkylphosphonate esters (RP(O)(OR')₂). Alkylation of phosphorus trichloride is effected in the presence of aluminium trichloride give the alkyltrichlorophosphonium salts, which are versatile intermediates:

PCl₃ + RCl + AlCl₃ → RPCl+3 + AlCl−4

The RPCl+3 product can then be decomposed with water to produce an alkylphosphonic dichloride RP(=O)Cl₂.

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 PCl₃ as a ligand

PCl₃, like the more popular phosphorus trifluoride, is a ligand in coordination chemistry. One example is Mo(CO)₅PCl₃.

 Uses

PCl₃ is important indirectly as a precursor to PCl₅, POCl₃ and PSCl₃, which are used in many applications, including herbicides, insecticides, plasticisers, oil additives, and flame retardants.

For example, oxidation of PCl₃ gives POCl₃, which is used for the manufacture of triphenyl phosphate and tricresyl phosphate, which find application as flame retardants and plasticisers for PVC. They are also used to make insecticides such as diazinon. Phosphonates include the herbicide glyphosate.

PCl₃ is the precursor to triphenylphosphine for the Wittig reaction, and phosphite esters which may be used as industrial intermediates, or used in the Horner-Wadsworth-Emmons reaction, both important methods for making alkenes. It can be used to make trioctylphosphine oxide (TOPO), used as an extraction agent, although TOPO is usually made via the corresponding phosphine.

PCl₃ is also used directly as a reagent in organic synthesis. It is used to convert primary and secondary alcohols into alkyl chlorides, or carboxylic acids into acyl chlorides, although thionyl chloride generally gives better yields than PCl₃.

 Safety

• 600 ppm is lethal in just a few minutes.
• 25 ppm is the US NIOSH "Immediately Dangerous to Life and Health" level
• 0.5 ppm is the US OSHA "permissible exposure limit" over a time-weighted average of 8 hours.
• 0.2 ppm is the US NIOSH "recommended exposure limit" over a time-weighted average of 8 hours.
• Under EU Directive 67/548/EEC, PCl₃ is classified as very toxic and corrosive , and the risk phrases R14, R26/28, R35 and R48/20 are obligatory.

Industrial production of phosphorus trichloride is controlled under the Chemical Weapons Convention, where it is listed in schedule 3, as it can be used to produce mustard agents.

 See also

• Phosphorus pentachloride
• Phosphoryl chloride
• Phosphorus trifluorodichloride