Irreversible reaction

Phosgenation of potassium tert-butyl carbonate to di-tert-butyl dicarbonate (amine-catalysed, net)

2KTBC+COCl2C10H18O5+CO2+2ClK

Direction
Irreversible
Processes
1
Stated as
Rate law
Heat of reaction
ΔH = -175,200 kJ/kmol (one process)
Element balance
Checked: balances
As the processes state itStoichiometry, conversions, heats of reaction and catalyst windows are taken from each process's files with their provenance. The build checks only that each process's equation balances in every element, from the process's own component formulas; it does not check the numbers. A process's design maturity applies to them.

Species

SpeciesNameCASRoleCoefficient
KTBCPotassium tert-butyl carbonate (suspended)none (not merged across processes)reactant-2
COCl2Phosgene75-44-5reactant-1
C10H18O5Di-tert-butyl dicarbonate24424-99-5product1
CO2Carbon dioxide124-38-9product1
ClKPotassium chloride7447-40-7product2

In the processes

  • Di-tert-butyl dicarbonate by semi-batch carbonation and phosgenation of potassium tert-butoxide (500 t/a)Concept · not reviewed

    PHOS · Phosgenation of potassium tert-butyl carbonate to di-tert-butyl dicarbonate (amine-catalysed, net)2 (CH3)3COC(O)OK + COCl2 → [(CH3)3COC(O)]2O + CO2 + 2 KCl

    Stated as
    Rate law
    Phase
    liquid
    Element balance
    Balances in every element
    Heat of reaction
    ΔH = -175,200 kJ/kmol at 298.15 K, as written (assumed: ASSUMED order of magnitude (D-005, D-015), per mol of phosgene dissolved, CO2 formed as a gas: -200 kJ/mol with phosgene as a gas less the dose's heat of solution, -24.8 kJ/mol, which R101's dose releases as the phosgene dissolves (core ADR 0063); the -200 kJ/mol: phosgene's hydrolysis to CO2 and HCl gas is about -73 kJ/mol (formation enthalpies, chemicals 1.5.2's CRC tables), and each HCl taken up by a carboxylate salt to solid KCl adds of the order of -60 kJ/mol; EP 0 256 559 A2 doses the phosgene slowly with external cooling because the reaction is exothermic; no calorimetric value)
    Rate law
    basis: volume; driving: concentration; form: power_law; k: {"A":"1.2273e8","Ea":50000}; orders: {"COCL2":1,"KTBC":1}; temperature range: 263.15 – 303.15 (assumed: ASSUMED fast effective rate (D-005): no open kinetics found (2026-11-06); fast enough that the phosgene dosing controls the heat (a plant with a dosing interlock aims for this); to be replaced by reaction calorimetry)

Sources

What the processes cite for this reaction, each source once: for the reaction itself, its conversion, its heat of reaction or its catalyst. As the processes write them; DOIs, US patent numbers and web addresses are linked.

  1. EP 0 256 559 A2, description and Example 1: the carbonate reacts with phosgene in the presence of a tertiary amine (DABCO, triethylamine) to Di-BOC directly, phosgene added over 4 h at 5 C with external cooling; without the amine scarcely any product (Comparative Example 1)

    For the reaction · cited by Di-tert-butyl dicarbonate by semi-batch carbonation and phosgenation of potassium tert-butoxide (500 t/a)

  2. ASSUMED order of magnitude (D-005, D-015), per mol of phosgene dissolved, CO2 formed as a gas: -200 kJ/mol with phosgene as a gas less the dose's heat of solution, -24.8 kJ/mol, which R101's dose releases as the phosgene dissolves (core ADR 0063); the -200 kJ/mol: phosgene's hydrolysis to CO2 and HCl gas is about -73 kJ/mol (formation enthalpies, chemicals 1.5.2's CRC tables), and each HCl taken up by a carboxylate salt to solid KCl adds of the order of -60 kJ/mol; EP 0 256 559 A2 doses the phosgene slowly with external cooling because the reaction is exothermic; no calorimetric value

    For the heat of reaction · cited by Di-tert-butyl dicarbonate by semi-batch carbonation and phosgenation of potassium tert-butoxide (500 t/a)