page_title: Physical organic chemistry
section_title: Catalysis
hierarchical_section_title: Physical organic chemistry / Kinetics / Catalysis
caption_attribution_description: English: catalytic reaction coordinate
context_page_description: Physical organic chemistry, a term coined by Louis Hammett in 1940, refers to a discipline of organic chemistry that focuses on the relationship between chemical structures and reactivity, in particular, applying experimental tools of physical chemistry to the study of organic molecules. Specific focal points of study include the rates of organic reactions, the relative chemical stabilities of the starting materials, reactive intermediates, transition states, and products of chemical reactions, and non-covalent aspects of solvation and molecular interactions that influence chemical reactivity. Such studies provide theoretical and practical frameworks to understand how changes in structure in solution or solid-state contexts impact reaction mechanism and rate for each organic reaction of interest.
context_section_description: The study of catalysis and catalytic reactions is very important to the field of physical organic chemistry. A catalyst participates in the chemical reaction but is not consumed in the process.  A catalyst lowers the activation energy barrier (ΔG‡), increasing the rate of a reaction by either stabilizing the transition state structure or destabilizing a key reaction intermediate, and as only a small amount of catalyst is required it can provide economic access to otherwise expensive or difficult to synthesize organic molecules. Catalysts may also influence a reaction rate by changing the mechanism of the reaction.
caption: Reaction coordinate energy diagram for uncatalysed and catalysed reactions, the latter without and with change in mechanism.[citation needed] Trace A. presents the uncatalysed reaction pathway (orange), with its free energy of activation. Trace B. presents a catalysed reaction pathway (blue), with its lowered relative free energy of activation. Trace C. presents a complex, altered reaction pathway (brown) for the same reaction proceeding by a different mechanism involving two kinetically discreet intermediates.
exif: {"Image XResolution": "72", "Image YResolution": "72", "Image ResolutionUnit": "Pixels/Inch", "Image ExifOffset": "78", "EXIF ExifImageWidth": "720", "EXIF ExifImageLength": "540"}