Process description of VSPP in Synthesis of D2EHPA mode

    Process description of VSPP in Synthesis of D2EHPA mode

    The VSPP set up at HWP-Talcher is intended for synthesis of D2EHPA, TOPO, TAPO & DNPPA. In the synthesis of D2EHPA, the entire process is divided into two Groups of operations. Each group operation is carried out in series in two different Reactors. The first set of operations consists of the operation steps 1 & 2 i.e. up to chlorination of DOP and is carried out in the 1st Reactor. After processing as above, the same charge is transferred into 2nd Reactor to take up second set of operation i.e. steps 3 to 5.

    The first Reactor is then made ready to take up first set of operation of the next batch parallel with the operation of second Reactor for 1st batch.

    The Synthesis process involves mainly five steps as given below:

    • Esterification reaction between phosphorous tri-chloride (PCl3) and 2-Ethyl Hexanol (ROH) to produce the first intermediate Di- Octyl Phosphite (DOP).
      Raw Materials used:
      • Phosphorous tri-chloride (PCl3)
      • Ethyl Hexanol (ROH) (R = C8H17)

      Reaction medium : n-Hexane

      Reaction involved

      PCl3(l) + 3ROH(l) ---------> (RO)2(O)H(l) + RCl(l) + 2HCl(g)

      (Di-Octyl Phosphite, DOP)

      R = C8H17 ( 2 Ethyl Hexyl radical )

    • Chlorination (Oxidation) of the DOP formed in the first step with Chlorine gas to from the second intermediate Di-Octyl Phosphochloridate(DOPC).
      Raw Materials used:
      • DOP from Step.1
      • Chlorine
      Reaction involved

      (RO)2(O)H (l) + Cl2 (g) ---------> (RO)2(O)Cl (l) + HCl (g)

      (Di-Octyl Phosphochloridate)

      R = C8H17 (2 Ethyl Hexyl radical)

    • Hydrolysis of the DOPC formed in 2nd step with Sodium Hydroxide solution (NaOH) to form raw D2EHPA.
      Raw Materials used:
      • D-Octyl Phosphochloridate from step 2
      • 2. Aqueous NaOH solution
      Reaction involved

      (RO)2(O)Cl (l) + NaOH ---------> (RO)2(P)(O)OH + NaCl (aq)


      R = C8H17 (2 – Ethyl Hexyl radical)

    • Water / dilute alkali washing of the raw product to remove undesirable impurities.
    • Final purification by vacuum distillation to obtain the product of desired quality.

    Last updated on: 04-Feb-2019