10294-56-1

Basic information

• Product Name: Phosphorous acid
• Synonyms: Phosphorous acid;Phosphorou acid;Phosphorous acid 50% aqueous solution
• CAS NO: 10294-56-1
• Molecular Formula: H₃O₃P
• Molecular Weight: 82
• EINECS: 233-663-1
• Mol File: 10294-56-1.mol
• Article Data: 11

Chemical Properties

• Melting Point: 73℃
• Appearance: COA
• PKA: 2.22±0.10(Predicted)
• Water Solubility: SOLUBLE
• CAS DataBase Reference: Phosphorous acid(CAS DataBase Reference)
• NIST Chemistry Reference: Phosphorous acid(10294-56-1)
• EPA Substance Registry System: Phosphorous acid(10294-56-1)

Safety Data

• Hazard Codes: Xn,C
• Statements: 22-35
• Safety Statements: 1/2-26-36/37/39-45
• RIDADR: UN 2834
• Hazardous Substances Data: 10294-56-1(Hazardous Substances Data)

Usage

Uses

Phosphorous acid is a reducer in chemical reactions and a raw material in the making of phosphorous acid salts. A plant defoliant.

Definition

A white crystalline solid. It is a monobasic acid forming the anion H2PO2- in water. The sodium salt, and hence the acid, can be prepared by heating yellow phosphorus with sodium hydroxide solution. The free acid and its salts are powerful reducing agents.

InChI:InChI=1/3H2O.H3P/h3*1H2;1H3/q;;;+3/p-3

Synthetic route

phosphorus → phosphorous acid (10294-56-1)

Conditions	Yield
With chlorine byproducts: HCl;

silver (I) ion (14701-21-4) + hypophosphorous acid (6303-21-5) → silver (7440-22-4) + phosphorous acid (10294-56-1)

Conditions	Yield
In perchloric acid Kinetics; oxidation hypophosphorous acid with silver(I) in aq. perchloric acid soln. at 30°C;

phosphorus tribromide (7789-60-8) → phosphonic Acid (13598-36-2) + phosphorous acid (10294-56-1)

Conditions	Yield
With water In neat (no solvent) formation of H3PO3 and P(OH)3 is proved by UV absorption and mild oxidation of products of hydrolysis;;

hydrogenchloride (7647-01-0) + phosphorus + water (7732-18-5) + butanone (78-93-3) → 1-hydroxy-1-methylpropylphosphine oxide + bis(1-hydroxy-1-methylpropyl)phosphine oxide + hypophosphorous acid (6303-21-5) + phosphorous acid (10294-56-1)

Conditions	Yield
With aluminium for 8h; Inert atmosphere; Schlenk technique; Sealed tube; Electrolysis;

hydrogenchloride (7647-01-0) + phosphorus + water (7732-18-5) + 2-Pentanone (107-87-9) → 1-hydroxy-1-methylbutylphosphine oxide + bis(1-hydroxy-1-methylbutyl)phosphine oxide + hypophosphorous acid (6303-21-5) + phosphorous acid (10294-56-1)

Conditions	Yield
With aluminium for 8h; Inert atmosphere; Schlenk technique; Sealed tube; Electrolysis;

hydrogenchloride (7647-01-0) + phosphorus + water (7732-18-5) → phosphoric acid (86119-84-8, 7664-38-2) + hypophosphorous acid (6303-21-5) + phosphorous acid (10294-56-1)

Conditions	Yield
With 3,3-dimethyl-butan-2-one; aluminium for 8h; Inert atmosphere; Schlenk technique; Sealed tube; Electrolysis;

triphenyl phosphite (101-02-0) → phenyl hydrogen phosphonate (2310-89-6) + phosphorous acid (10294-56-1)

Conditions	Yield
With [Pt(H2O)2(1,1'-bis(diphenylphosphanyl)octamethylferrocene)](trifluoromethylsulfonate)2; water In tetrahydrofuran at 20℃; for 8h; Catalytic behavior; Mechanism; Reagent/catalyst; Solvent; Inert atmosphere; Schlenk technique; Sealed tube;

diphenyl hydrogen phosphite (4712-55-4) → phenyl hydrogen phosphonate (2310-89-6) + phosphorous acid (10294-56-1)

Conditions	Yield
With water In tetrahydrofuran at 20℃; for 0.5h; Inert atmosphere; Schlenk technique; Sealed tube;

tris-(2-chloro, 1-methylethyl)-phosphate (13674-84-5) → LACTIC ACID (849585-22-4) + propylene glycol (57-55-6) + 1-hydroxypropan-2-yl dihydrogenphosphate (14807-82-0) + diisopropylphosphate (1611-31-0) + triisopropyl phosphate (513-02-0) + cis-1-chloropropene (16136-84-8) + carbon dioxide (124-38-9) + phosphoric acid (86119-84-8, 7664-38-2) + bis(1-hydroxypropan-2-yl) hydrogenphosphate + chloride (16887-00-6) + oxalic acid (144-62-7) + hydrogen cation + Phosphate (14265-44-2) + isopropyl alcohol (67-63-0) + phosphorous acid (10294-56-1)

Conditions	Yield
With dihydrogen peroxide In water UV-irradiation;

...Expand

lauric acid (143-07-7) + phosphorus trichloride (7719-12-2, 52843-90-0) → phosphorous acid (10294-56-1)

Conditions	Yield
at 63℃; for 3h;

benzylamine (100-46-9) + phosphorous acid (10294-56-1) → dibenzylamine (103-49-1)

Conditions	Yield
With benzaldehyde; triethylamine	98%

β-naphthol (135-19-3) + phosphorous acid (10294-56-1) → N-Phenyl-2-naphthylamine (135-88-6)

Conditions	Yield
With aniline In water	94%

hydrogenchloride (7647-01-0) + molybdenum(VI) oxide + potassium hydroxide + phosphorous acid (10294-56-1) → 1.7K(1+)*0.3H(1+)*HPMo6O21(2-)

Conditions	Yield
In water at 100℃; for 6h; pH=Ca. 1.5; Temperature; Autoclave;	92%

o-toluidine (95-53-4) + phosphorous acid (10294-56-1) + recorcinol (108-46-3) → 3-(o-tolylamino)phenol (6264-98-8)

Conditions	Yield
In water	90%

tris(4-(1H-imidazol-1-yl)-phenyl)amine (1258947-79-3) + water (7732-18-5) + zinc(II) oxide + phosphorous acid (10294-56-1) → [Zn3(HPO3)3(tris(4-(1H-imidazol-1-yl)phenyl)amine)]·6H2O

Conditions	Yield
With hydrogen fluoride In N,N-dimethyl-formamide at 145℃; for 168h; Autoclave;	90%

N-methyltetrahydro-3-thiophenamine 1,1-dioxide hydrochloride + phosphorous acid (10294-56-1) → tetrahydro-N-methyl-N-(phosphonomethyl)-3-thiophenamine 1,1-dioxide

Conditions	Yield
With paraformaldehyde In P2 O5; ethanol; water	86.3%

piperazine (110-85-0) + methanol (67-56-1) + zinc(II) acetate dihydrate (5970-45-6) + phosphorous acid (10294-56-1) → [N,N,N′,N′-tetramethylpiperazinium]0.5[Zn2(HPO3)2(H2PO3)]

Conditions	Yield
In water at 160℃; for 168h; Autoclave; High pressure;	82.6%

Ru(NH3)5Cl(2+)*2Cl(1-)=Ru(NH3)5Cl3 + carbon monoxide (201230-82-2) + water (7732-18-5) + phosphorous acid (10294-56-1) + zinc amalgam → CH15N4O4PRu(2+)*Cl4Zn(2-)*H2O

Conditions	Yield
Stage #1: Ru(NH3)5Cl(2+)*2Cl(1-)=Ru(NH3)5Cl3; water; zinc amalgam With trifluoroacetic acid for 0.666667h; Inert atmosphere; Stage #2: phosphorous acid for 1h; Inert atmosphere; Stage #3: carbon monoxide for 5h;	82%

benzylamine (100-46-9) + phosphorous acid (10294-56-1) → N-benzylcyclohexylamine (4383-25-9)

Conditions	Yield
	80%

iron(II) chloride hexahydrate + sodium hydroxide (1310-73-2) + phosphorous acid (10294-56-1) → 2Na(1+)*Fe(2+)*2HPO3(2-)=Na2Fe(HPO3)2

Conditions	Yield
With NH3*H2O In water High Pressure; Fe salt, NaOH, H3PO4 and H2O mixed in molar ratio 2:2.5:2.5:667, treatedwith NH3*H2O soln. to pH=7.0, sealed in stainless sleel autoclave, heat ed at 433 K for 5 d; filtered, washed (ethanol), dried at room temp., XRD, elem. anal.;	80%

phosphorous acid (10294-56-1) + iminodiacetic acid (142-73-4) → phosphonomethylimino-di-acetic acid (5994-61-6)

Conditions	Yield
With formaldehyd; sulfuric acid	78.2%
With formaldehyd; sulfuric acid	75.3%
With formaldehyd; sulfuric acid	74.2%
With formaldehyd; sulfuric acid In water	59.8%

zinc(II) nitrate hexahydrate + 1,12-Diaminododecane (2783-17-7) + terephthalic acid (100-21-0) + hydrogen fluoride (7664-39-3) + phosphorous acid (10294-56-1) → (H2DIA)Zn2(1,4-benzenedicarboxylate)(HPO3)2

Conditions	Yield
In water; N,N-dimethyl-formamide at 150℃; for 48h;	78%

methanol (67-56-1) + zinc(II) acetate dihydrate (5970-45-6) + (RS)-2-methylpiperazine (109-07-9) + phosphorous acid (10294-56-1) → [N,N,N’,N’-tetramethyl-2-methylpiperazinium][Zn3(HPO3)4]

Conditions	Yield
In water at 155℃; for 168h; Autoclave;	77.4%

Thiophene-2,5-dicarboxylic acid (4282-31-9) + zinc(II) nitrate hexahydrate + 1,12-Diaminododecane (2783-17-7) + phosphorous acid (10294-56-1) → C12H28N2*2HO3P(2-)*C6H2O4S(2-)*2H(1+)*2Zn(2+)

Conditions	Yield
In water; N,N-dimethyl-formamide at 150℃; for 48h; Autoclave;	76%

1,4-diazabicyclo[2.2.2]octane hexahydrate + zinc(II) acetate dihydrate (5970-45-6) + phosphorous acid (10294-56-1) → Zn(dabco)0.5(HPO3)

Conditions	Yield
In ethanol; water at 160℃; for 216h;	72.1%

1-(N-morpholino)cyclopent-1-ene (936-52-7) + phosphorous acid (10294-56-1) → N-cyclopentylmorpholine (39198-78-2)

Conditions	Yield
	72%

4,4'-bipyridine dihydrate + vanadia + phosphorous acid (10294-56-1) → (VO)4((4,4'-bipyridine)2(HPO3)4

Conditions	Yield
With (CH3)4NOH*5H2O In water High Pressure; mixt. of V2O5, H3PO3, bipyridine, (CH3)4NOH*5H2O and distd. H2O (ratio 1:10:2:8:555) heated at 160°C for 120 h; washed (distd. H2O), filtered, dried in air; elem. anal.;	72%

cobalt(II) chloride hexahydrate + sodium hydroxide (1310-73-2) + phosphorous acid (10294-56-1) → 2Na(1+)*Co(2+)*2HPO3(2-)=Na2Co(HPO3)2

Conditions	Yield
With NH3*H2O In water High Pressure; Co salt, NaOH, H3PO4 and H2O mixed in molar ratio 2:2.5:2.5:667, treatedwith NH3*H2O soln. to pH=7.0, sealed in stainless sleel autoclave, heat ed at 433 K for 5 d; filtered, washed (ethanol), dried at room temp., XRD, elem. anal.;	70%

dimethyl 6,6′-([ethane-1,2-diylbis{azanediyl}]bis[methylene])dipicolinate (761411-41-0) + phosphorous acid (10294-56-1) → N,N'-(methylphosphonate)-N,N'-[[6-(methoxycarbonyl)pyridin-2-yl]methyl]-1,2-diaminoethane

Conditions	Yield
With 1,3,5-Trioxan; hydrogenchloride Reflux;	70%

tris(4-(1H-imidazol-1-yl)-phenyl)amine (1258947-79-3) + water (7732-18-5) + zinc(II) oxide + phosphorous acid (10294-56-1) → [Zn2(HPO3)2(tris(4-(1H-imidazol-1-yl)phenyl)amine)]·2H2O

Conditions	Yield
In N,N-dimethyl-formamide at 145℃; for 168h; Autoclave;	70%

1,4-diaza-bicyclo[2.2.2]octane (280-57-9) + methanol (67-56-1) + zinc(II) oxide + phosphorous acid (10294-56-1) → [N,N'-dimethyl-1,4-diazabicyclo[2,2,2]octane][Zn3(HPO3)4]

Conditions	Yield
In water at 160℃; for 168h; Autoclave;	68.7%

sodium molybdate dihydrate (7631-95-0) + 1,3,5,-tris(4-carboxyphenyl)benzene (50446-44-1) + tetra(n-butyl)ammonium hydroxide (2052-49-5) + zinc(II) chloride (7646-85-7) + phosphorous acid (10294-56-1) + molybdenum (7439-98-7) → [tetrabutylammonium]3[ε-PMoV8MoVI4O36(OH)4Zn4][benzene tribenzoate]4/3

Conditions	Yield
With hydrogenchloride In water at 180℃; for 72h; pH=4.8; Autoclave;	68%

sodium molybdate dihydrate (7631-95-0) + zinc(II) acetate dihydrate (5970-45-6) + trans-1,2-bis(pyridin-4-yl)ethene (13362-78-2) + tetrapropylammonium hydroxide (4499-86-9) + phosphorous acid (10294-56-1) + molybdenum (7439-98-7) → Mo12O40PH3Zn4*3C12H10N2

Conditions	Yield
Stage #1: sodium molybdate dihydrate; zinc(II) acetate dihydrate; trans-1,2-bis(pyridin-4-yl)ethene; tetrapropylammonium hydroxide; phosphorous acid; molybdenum In water for 1h; Sealed tube; Stage #2: With hydrogenchloride In water for 0.5h; pH=4.2; Sealed tube; Stage #3: In water at 180℃; for 72h; Sealed tube;	67.11%

gallium(III) sulfate + potassium carbonate (584-08-7) + phosphorous acid (10294-56-1) → 2HO3P(2-)*Ga(3+)*K(1+)

Conditions	Yield
In water at 179.84℃; for 72h; High pressure; Autoclave;	67%

rubidium carbonate + gallium(III) sulfate + phosphorous acid (10294-56-1) → 2HO3P(2-)*Ga(3+)*Rb(1+)

Conditions	Yield
In water at 179.84℃; for 72h; High pressure; Autoclave;	67%

gallium(III) sulfate + ammonium carbonate (506-87-6) + phosphorous acid (10294-56-1) → H2O3P(1-)*Ga(3+)*H3N*HO3P(2-)

Conditions	Yield
In water at 179.84℃; for 72h; High pressure; Autoclave;	67%

zinc(II) nitrate hexahydrate + n-Octylamine (111-86-4) + terephthalic acid (100-21-0) + hydrogen fluoride (7664-39-3) + phosphorous acid (10294-56-1) → (HOCA)Zn(1,4-benzenedicarboxylate)0.5(HPO3)

Conditions	Yield
In water; N,N-dimethyl-formamide at 150℃; for 48h;	67%

K[Gd(ethylenediaminetetraacetate)(trihydrate)]*5H2O + phosphorous acid (10294-56-1) → K3n[Gd(ethylenediaminetetraacetate)(phosphite)]n*7nH2O

Conditions	Yield
With potassium hydroxide In water at 70℃; for 168h; pH=7.2;	65%

1,4-diaza-bicyclo[2.2.2]octane (280-57-9) + cobalt(II) chloride hexahydrate + phosphorous acid (10294-56-1) → Co(2+)*2HO3P(2-)*C6H12N2*2H(1+)

Conditions	Yield
Stage #1: 1,4-diaza-bicyclo[2.2.2]octane; cobalt(II) chloride hexahydrate In N,N-dimethyl-formamide for 3h; Stage #2: phosphorous acid In N,N-dimethyl-formamide at 60℃; for 72h; Sealed tube;	65%

Upstream product

• 14701-21-4 silver (I) ion 
• 6303-21-5 hypophosphorous acid 
• 143-07-7 lauric acid 
• 7719-12-2 phosphorus trichloride 
• 7732-18-5 water 
• 13674-84-5 tris-(2-chloro, 1-methylethyl)-phosphate 
• 4712-55-4 diphenyl hydrogen phosphite 
• 101-02-0 triphenyl phosphite 
• 7647-01-0 hydrogenchloride 
• 107-87-9 2-Pentanone 
• 78-93-3 butanone 
• 7789-60-8 phosphorus tribromide 

Downstream Products

• 5994-61-6 phosphonomethylimino-di-acetic acid 
• 18999-45-6 3-(imidazol-1-yl)-propionic acid 
• 57637-97-5 N-acetylaminomethylphosphonic acid 
• 105462-24-6 risedronic acid 
• 6881-56-7 N-benzoylaminomethylphosphonic acid 
• 114084-74-1 3-(N-Cyclohexyl-N-methylamino)-1-hydroxy-propane-1,1-diphosphonic acid 
• 65922-85-2 5-methylmorpholin-3-one 
• 53019-19-5 hydroxyoctane-1, 1-diphosphonic acid 
• 103-67-3 benzyl-methyl-amine 
• 109-02-4 4-methyl-morpholine 
• 42882-36-0 benzyl(2-methylpropyl)amine 
• 4383-25-9 N-benzylcyclohexylamine 
• 103-49-1 dibenzylamine 
• 103-83-3 N,N'-dimethylbenzylamine 

Relevant articles and documents

Hydrolysis of element (White) phosphorus under the action of heterometallic cubane-type cluster {mo3pds4}

Reaction of heterometallic cubane-type cluster complexes—[Mo3{Pd(dba)}S4Cl3(dbbpy)3]PF6, [Mo3{Pd(tu)}S4Cl3(dbbpy)3]Cl and [Mo3{Pd(dba)}S4/s

Kinetics and mechanism of oxidation of hypophosphorous acid with silver(I) in aqueous perchloric acid solutions

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PROCESS FOR THE PRODUCTION OF A FERTILIZER

Process for the production of a compound comprising potassium phosphite comprising the steps of (a) reacting carboxylic acid of the formula R-(C(=O)OH)n with phosphorous trichloride (PCl3) towards a mixture comprising phosphorous acid (H3PO3) and acid chloride of the formula R-(C(=O)Cl)n; wherein R is a linear or branched alkyl or alkanediyl group with 1-20 carbon atoms and n is 1 or 2, (b) subjecting said mixture to a separation step, thereby obtaining (i) a fraction comprising crude phosphorous acid (H3PO3) and (ii) a fraction comprising acid chloride, (c) combining water, a potassium compound selected from KOH, KHCO3 and K2CO3, and the fraction comprising crude phosphorous acid, thereby forming an aqueous solution comprising potassium phosphite, and (d) removing organic compounds from said aqueous solution.