Monsanto process

Monsanto Process

	Email		Print
	Bookmark		Link

Monsanto process

The Monsanto process is an important method for the manufacture of acetic acid

Acetic acid

Acetic acid, CH3COOH, also known as ethanoic acid, is an organic acid which gives vinegar its sour taste and pungent smell. Pure, water-free acetic acid is a colourless liquid that absorbs water from the environment , and freezes at 16.7 Celsius to a colourless crystalline solid....
. This process operates at a pressure

Pressure

Pressure is the force per unit area applied to an object in a direction surface normal to the surface. Gauge pressure is the pressure relative to the local atmospheric or ambient pressure....
of 30-60 atm

Atmosphere (unit)

The standard atmosphere is an international reference pressure defined as 101,325 Pascal and formerly used as unit of pressure . For practical purposes it has been replaced by the Bar which is 100,000 Pa....
and a temperature

Temperature

In physics, temperature is a physical property of a Physical system that underlies the common notions of hot and cold; something that feels hotter generally has the greater temperature....
of 150-200 °C and gives a selectivity greater than 99%. The Monsanto process has largely been supplanted by the Cativa process

Cativa process

The Cativa process is a method for the production of acetic acid by the carbonylation of methanol. The technology, which is similar to the Monsanto process, was developed by BP Chemicals and is under license by BP Plc....
, a similar iridium

Iridium

Iridium is the chemical element with atomic number 77, and is represented by the symbol Ir. A very hard, brittle, silvery-white transition metal of the platinum group, iridium is the second densest element and is the most corrosion-resistant metal, even at temperatures as high as 2000 ?C....
-based process developed by BP Chemicals Ltd

BP plc , is the third largest global energy corporation, a multinational corporation oil company with headquarters in London. The company is among the largest private sector energy corporations in the world, and one of the six "supermajors" ....
which is more economical and environmentally friendly.

catalytically

Catalysis

Catalysis is the process in which the reaction rate of a chemical reaction is either increased or decreased by means of a chemical substance known as a catalyst....
active species is the anion cis-Rh(CO)₂I₂^- (1).

Discussion

Ask a question about 'Monsanto process'

Start a new discussion about 'Monsanto process'

Answer questions from other users

Full Discussion Forum

Catalytic cycle

The catalytically

Catalysis

Catalytic cycle

A catalytic cycle in chemistry is a term for a multistep reaction mechanism that involves a catalyst . The catalytic cycle is the main method for describing the role of catalysts in biochemistry, organometallic chemistry, materials science, etc....
has been shown to involve six steps, two of which do not involve rhodium: conversion of methanol to methyl iodide and the hydrolysis of the acetyl iodide

Acetyl iodide

Acetyl iodide, C2H3IO, also known as ethanoyl iodide, is an acyl halide derived from acetic acid. Acetyl iodide is an intermediate in the Monsanto process....
to acetic acid. The first organometallic

Organometallic chemistry

Organometallic chemistry is the study of chemical compounds containing chemical bonding between carbon and a metal. Since many compounds without such bonds are chemically similar, an alternative may be compounds containing metal-element bonds of a largely covalent character....
step is the oxidative addition

Oxidative addition

Oxidative addition and reductive elimination are two important classes of reactions in organometallic chemistry . Their relationship is shown below where y represents the number of ligands on the metal and n is the oxidation state of the metal....
of methyl iodide to cis-Rh(CO)₂I₂^- to form the hexacoordinate

Octahedral molecular geometry

In chemistry, octahedral molecular geometry describes the shape of compounds where in six atoms or groups of atoms or ligands are symmetrically arranged around a central atom, defining the vertices of an octahedron....
species (CH₃)Rh(CO)₂I₃^- (2). This anion rapidly transforms, via the migration of a methyl group to the carbonyl

Carbonyl

In organic chemistry, a carbonyl group is a functional group composed of a carbon atom double bond to an oxygen atom : C=O.The term carbonyl can also refer to carbon monoxide as a ligand in an inorganic or organometallic complex ; in this situation, carbon is triple-bonded to oxygen : C=O....
ligand

Ligand

In chemistry, a ligand is either an atom, ion, or molecule that bonds to a central metal, generally involving formal donation of one or more of its electrons....
, affording the pentacoordinate acetyl

Acetyl

In organic chemistry, acetyl , is a functional group, the acyl of acetic acid, with chemical formula -CarbonOxygenCarbonHydrogen3. It is sometimes abbreviated as Ac ....
complex (CH₃CO)Rh(CO)I₃^- (3). This five-coordinate complex then reacts with carbon monoxide

Carbon monoxide

Carbon monoxide, with the chemical formula CO, is a colorless and odorless, tasteless, yet highly toxic gas. Its molecules consist of one carbon atom covalent bond to one oxygen atom....
to form the six coordinate dicarbonyl complex (4) which decomposes by reductive elimination to form acetyl iodide

Acetyl iodide

Acetyl iodide, C2H3IO, also known as ethanoyl iodide, is an acyl halide derived from acetic acid. Acetyl iodide is an intermediate in the Monsanto process....
(CH₃COI) and regenerate the active form of the catalyst. Acetic acid iodine is then hydrolyzed to acetic acid

Acetic acid

Rate-determining step

The rate-determining step is a chemistry term for the slowest reaction step in a chemical reaction. The rate-determining step is often compared to the neck of a funnel; the rate at which water flows through the funnel is determined by the width of the neck, not by the speed at which water is poured in....
of the catalytic cycle has been proposed to be the oxidative addition

Oxidative addition

Tennessee Eastman Acetic Anhydride Process

Acetic anhydride

Acetic anhydride is the chemical compound with the chemical formula 2O. Commonly abbreviated Acetyl2O, it is one of the simplest acid anhydrides and is a widely used reagent in organic synthesis....
is produced by carbonylation

Carbonylation

Carbonylation refers to Chemical_reactions that introduce carbon monoxide into Organic_compound and inorganic compound substrates. Carbon monoxide is abundantly available and conveniently reactive, so it is widely used as a reactant in industrial chemistry....
of methyl acetate

Methyl acetate

Methyl acetate, also known as acetic acid methyl ester or methyl ethanoate, is a clear, flammable liquid with a characteristic, not unpleasant smell like certain glues or nail polish removers....
in a process that was inspired by the Monsanto acetic acid synthesis.

CH₃CO₂CH₃ + CO ? (CH₃CO)₂O

In this process methyl acetate converts to methyl iodide, which in turn affords acetyl iodide, which reacts with acetate salts or acetic acid to give the product. Rhodium iodides and lithium salts are employed as catalysts. Because acetic anhydride is not stable in water, the conversion is conducted under anhydrous conditions in contrast to the Monsanto acetic acid synthesis.