Hydrogenolysis

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Hydrogenolysis

Hydrogenolysis is a chemical reaction

Chemical reaction

A chemical reaction is a process that always results in the interconversion of chemical substances. The substance or substances initially involved in a chemical reaction are called reactants....
whereby a carbon-carbon or carbon-heteroatom

Heteroatom

In the organic nomenclature of organic chemistry, a heteroatom is any atom that is not carbon or hydrogen. It is typically, but not exclusively, nitrogen, oxygen, sulfur, phosphorus, boron, chlorine, bromine, or iodine....
single bond is cleaved or undergoes "lysis" by hydrogen. The heteroatom may vary, but it usually is oxygen, nitrogen, or sulfur. A related reaction is hydrogenation

Hydrogenation

Hydrogenation is the chemical reaction that results from the addition of hydrogen . The process is usually employed to a redox or Saturation organic compounds....
, where hydrogen is added to the molecule, without cleaving bonds. Usually hydrogenolysis is conducted catalytically using hydrogen gas.

term "hydrogenolysis" was coined by Carleton Ellis

Carleton Ellis

Carleton Ellis was an American inventor and a pioneer in the field of organic chemistry. He is the forgotten father of margarine, polyester, anti-knock gasoline, paint and varnish remover, and holder of 753 patents ....
in reference to hydrogenolysis of carbon-carbon bonds.

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Encyclopedia

Hydrogenolysis is a chemical reaction

Chemical reaction

Heteroatom

Hydrogenation

History

The term "hydrogenolysis" was coined by Carleton Ellis

Carleton Ellis

Paul Sabatier (chemist)

Paul Sabatier was a French chemist, born at Carcassonne. He taught science classes most of his life before he became Dean of the Faculty of Science in 1905....
had already observed the hydrogenolysis of benzyl alcohol to toluene, and as early as 1906, Padoa and Ponti had observed the hydrogenolysis of furfuryl alcohol

Furfuryl alcohol

Furfuryl alcohol, also called 2-furylmethanol or 2-furancarbinol, is an organic compound containing a furan substitited with a hydroxymethyl group....
. Adkins and Connors were the first to call the carbon-oxygen bond cleavage "hydrogenolysis".

In the petrochemical industry

In petroleum refineries

Oil refinery

An oil refinery is an industrial process plant where crude oil is processed and refined into more useful petroleum products, such as gasoline, diesel fuel, asphalt, heating oil, kerosene, and liquefied petroleum gas....
, catalytic hydrogenolysis of feedstocks is conducted on a large scale to remove sulfur from feedstocks, releasing gaseous hydrogen sulfide

Hydrogen sulfide

Hydrogen sulfide is the chemical compound with the chemical formula Hydrogen2Sulfur. This colorless, toxic and flammable gas is partially responsible for the foul odor of egg and flatulence....
(H₂S). The hydrogen sulfide is subsequently recovered in an amine treater and finally converted to elemental sulfur

Sulfur

Sulfur or sulphur is the chemical element that has the atomic number 16. It is denoted with the symbol S. It is an abundant Valence non-metal....
in a Claus process

Claus process

The Claus process is the most significant gas desulfurizing process, recovering elemental sulfur from gaseous hydrogen sulfide. First invented over 100 years ago, the Claus process has become the industry standard....
unit. In those industries, desulfurization process units are often referred to as hydrodesulfurizers

Hydrodesulfurization

Hydrodesulfurization is a catalytic chemical process widely used to remove sulfur from natural gas and from oil refinery such as gasoline, jet fuel, kerosene, diesel fuel, and fuel oils....
(HDS) or hydrotreaters (HDT). Catalysts are based on molybdenum sulfide containing smaller amounts of cobalt or nickel. Hydrogenolysis is accompanied by hydrogenation.

Another hydrogenolysis reaction of commercial importance is the hydrogenolysis of esters into alcohols by catalysts such as copper chromite.

In the laboratory

In the laboratory, hydrogenolysis is used in organic synthesis

Organic synthesis

Organic synthesis is a special branch of chemical synthesis and is concerned with the construction of organic compounds via organic reactions. Organic_chemistry molecules can often contain a higher level of complexity compared to purely Inorganic_chemistry compounds, so the synthesis of organic compounds has developed into one of the most im...
. Debenzylation is most common and involves the cleavage of benzyl

Benzyl

In organic chemistry, benzyl is the term used to describe the substituent or molecular fragment possessing the structure C6H5CH2-....
ethers:

ROCH₂C₆H₅ + H₂ ? ROH + CH₃C₆H₅

Thioketal

A thioketal in chemistry is the sulfur analogue of a ketal with one of the oxygen replaced by sulfur. A dithioketal has both oxygenes replaced by sulfur....
s undergo hydrogenolysis using Raney Nickel

Raney nickel

Raney nickel is a solid catalyst composed of fine grains of a nickel-aluminium alloy, used in many industrial processes. It was developed in 1926 by United States engineer Murray Raney as an alternative catalyst for the hydrogenation of vegetable oils in industrial processes....
, a catalyst that, conveniently, carries its own hydrogen.