Phosphorus pentasulfide

Phosphorus pentasulfide is the inorganic compound with the formula P₂S₅ (empirical) or P₄S₁₀ (molecular). This yellow solid is the one of two phosphorus sulfides of commercial value. Samples often appear greenish-gray due to impurities. It is soluble in carbon disulfide but reacts with many other solvents such as alcohols, DMSO, and DMF.^[3]

Phosphorus pentasulfide

Phosphorus decasulfide
Phosphorus decasulfide
Names
Other names Phosphorus sulfide Sulfur phosphide Phosphorus persulfide Diphosphorus pentasulfide Tetraphosphorus decasulfide Phosphorus decasulfide
Identifiers
CAS Number	1314-80-3 Y
3D model (JSmol)	Interactive image
ChemSpider	14133 N
ECHA InfoCard	100.013.858
EC Number	215-242-4
PubChem CID	14817
RTECS number	TH4375000
UNII	HJ1X20J1DX Y
CompTox Dashboard (EPA)	DTXSID0051659
InChI InChI=1S/P4S10/c5-1-9-2(6)12-3(7,10-1)14-4(8,11-1)13-2 N Key: CYQAYERJWZKYML-UHFFFAOYSA-N N InChI=1/P4S10/c5-1-9-2(6)12-3(7,10-1)14-4(8,11-1)13-2 Key: CYQAYERJWZKYML-UHFFFAOYAD
SMILES P12(=S)SP3(=S)SP(=S)(S1)SP(=S)(S2)S3
Properties
Chemical formula	P4S10
Molar mass	444.50 g/mol
Appearance	Yellow solid
Odor	Rotten eggs[1]
Density	2.09 g/cm3
Melting point	288 °C (550 °F; 561 K)
Boiling point	514 °C (957 °F; 787 K)
Solubility in water	Hydrolyses
Solubility in other solvents	0.222 g in 100 g carbon disulfide (at 17 °C) Insoluble in benzene Insoluble in hot xylene Insoluble in hot anisole
Vapor pressure	1 mmHg (300 °C)[1]
Structure
Crystal structure	triclinic, aP28
Space group	P1 (No. 2)
Point group	Td
Hazards
Lethal dose or concentration (LD, LC):
LD50 (median dose)	389 mg/kg (oral, rat)[2]
NIOSH (US health exposure limits):
PEL (Permissible)	TWA 1 mg/m3[1]
REL (Recommended)	TWA 1 mg/m3 ST 3 mg/m3[1]
IDLH (Immediate danger)	250 mg/m3[1]
Related compounds
Related compounds	Diphosphorus trisulfide Phosphorus sesquisulfide Phosphorus sulfides
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

Structure and synthesis

Its tetrahedral molecular structure is similar to that of adamantane and almost identical to the structure of phosphorus pentoxide.^[4]

Phosphorus pentasulfide is obtained by the reaction of liquid white phosphorus (P₄) with sulfur above 300 °C. The first synthesis of P₄S₁₀ by Berzelius in 1843^[5] was by this method. Alternatively, P₄S₁₀ can be formed by reacting elemental sulfur or pyrite, FeS₂, with ferrophosphorus, a crude form of Fe₂P (a byproduct of white phosphorus (P₄) production from phosphate rock):

4 Fe₂P + 18 S → P₄S₁₀ + 8 FeS

4 Fe₂P + 18 FeS₂ heat→ P₄S₁₀ + 26 FeS

Applications

Approximately 150,000 tons of P₄S₁₀ are produced annually. The compound is mainly converted to other derivatives for use as lubrication additives such as zinc dithiophosphates. It is widely used in the production of sodium dithiophosphate for applications as a flotation agent in the concentration of molybdenite minerals. It is also used in the production of pesticides such as Parathion and Malathion.^[6] It is also a component of some amorphous solid electrolytes (e.g. Li₂S-P₂S₅) for some types of lithium batteries.

Phosphorus pentasulfide is a dual-use material, for the production of early insecticides such as Amiton and also for the manufacture of the related VX nerve agents.

Phosphorus pentasulfide reacts with ethanol to give diethyl dithiophosphoric acid:^[7]

P₂S₅ + 4 C₂H₅OH → 2 (C₂H₅O)₂PS₂H + H₂S

diorganodithiophosphoric acids are used to produce metal dithiophosphates.

Reactivity

Due to hydrolysis by atmospheric moisture, P₄S₁₀ evolves hydrogen sulfide H₂S, thus P₄S₁₀ is associated with a rotten egg odour. Aside from H₂S, hydrolysis of P₄S₁₀ eventually gives phosphoric acid:

P₄S₁₀ + 16 H₂O → 4 H₃PO₄ + 10 H₂S

Other mild nucleophiles react with P₄S₁₀, including alcohols and amines. Reaction with ammonium chloride gives the polymeric (SPN)_∞.^[8] Aromatic compounds such as anisole, ferrocene and 1-methoxynaphthalene react to form 1,3,2,4-dithiadiphosphetane 2,4-disulfides such as Lawesson's reagent:

P₄S₁₀ + 4 ArH → 2 [ArPS₂]₂ + 2 H₂S (Ar = aryl)

P₄S₁₀ is used as a thionation reagent. Reactions of this type require refluxing solvents such as benzene, dioxane, or acetonitrile with P₄S₁₀ dissociating into P₂S₅. Some ketones, esters, and imides are converted to the corresponding thiocarbonyls. Amides give thioamides. With 1,4-diketones the reagent forms thiophenes. It is also used to deoxygenate sulfoxides. The use of P₄S₁₀ has been displaced by the aforementioned Lawesson's reagent.^[9]

P₄S₁₀ reacts with pyridine to form the complex P₂S₅(pyridine)₂.^[10]