The Phosphorous acid, with the CAS registry number 10294-56-1, is also known as Caswell No. 663I. Its EINECS registry number is 233-663-1. This chemical's molecular formula is H₃PO₃ and molecular weight is 81.995781. Its IUPAC name is called phosphorous acid. Phosphorous acid is the production of phosphonates which are used in water treatment. Phosphorous acid is also used for preparing phosphite salts, such as potassium phosphite. 

Physical properties of Phosphorous acid are: (1)ACD/LogP: -0.76; (2)ACD/LogD (pH 5.5): -4.01; (3)ACD/LogD (pH 7.4): -5.49; (4)ACD/BCF (pH 5.5): 1.00; (5)ACD/BCF (pH 7.4): 1.00; (6)#H bond acceptors: 3; (7)#H bond donors: 3; (8)#Freely Rotating Bonds: 3

Preparation of Phosphorous acid: 

HPO(OH)₂ is the product of the hydrolysis of its acid anhydride:
P₄O₆ + 6 H₂O → 4 HPO(OH)₂
(An analogous relationship connects H₃PO₄ and P₄O₁₀).
On an industrial scale, the acid is prepared by hydrolysis of phosphorus trichloride with water or steam:
PCl₃ + 3 H₂O → HPO(OH)₂ + 3 HCl
Potassium phosphite is also a convenient precursor to phosphorous acid:
K₂HPO₃ + 2 HCl → 2 KCl + H₃PO₃
In practice aqueous potassium phosphite is treated with excess hydrochloric acid. By concentrating the solution and precipitations with alcohols, the pure acid can be separated from the salt.

Uses of Phosphorous acid: The most important use of phosphorous acid is the production of phosphonates which are used in water treatment. Phosphorous acid is also used for preparing phosphite salts, such as potassium phosphite.

When you are using this chemical, please be cautious about it as the following:
This chemical may cause damage to health and may destroy living tissue on contact. It is harmful if swallowed which may cause severe burns. In case of contact with eyes, you should rinse immediately with plenty of water and seek medical advice. Whenever you will contact it, please wear suitable protective clothing, gloves and eye/face protection.

You can still convert the following datas into molecular structure:
(1)Canonical SMILES: OP(O)O
(2)InChI: InChI=1S/H3O3P/c1-4(2)3/h1-3H
(3)InChIKey: OJMIONKXNSYLSR-UHFFFAOYSA-N