Editing Destructive distillation (section)

{{Short description|Chemical process}}
'''Destructive distillation''' is a [[chemical process]] in which [[Thermal decomposition|decomposition]] of [[Raw material|unprocessed material]] is achieved by heating it to a high temperature; the term generally applies to processing of [[Organic chemistry|organic]] material in the absence of air or in the presence of limited amounts of oxygen  or other [[reagents]], [[Catalysis|catalysts]], or [[solvents]], such as [[steam]] or [[phenols]]. It is an application of [[pyrolysis]]. The process breaks up or "[[Cracking (chemistry)|cracks]]" large molecules. [[Coke (fuel)|Coke]], [[coal gas]], [[gas carbon|gaseous carbon]], [[coal tar]], [[ammonium hydroxide|ammonia liquor]], and [[coal oil]] are examples of commercial products historically produced by the destructive distillation of [[coal]].

[[Image:Distillation_by_Retort.png|thumb|300px|Many early experiments used [[retort]]s for destructive distillation.]]

Destructive distillation of any particular inorganic feedstock produces only a small range of products as a rule, but destructive distillation of many organic materials commonly produces very many compounds, often hundreds, although not all products of any particular process are of commercial importance. The distillate are generally lower molecular weight. Some fractions however [[polymerise]] or [[Condensation reaction|condense]] small molecules into larger molecules, including heat-stable [[tar]]ry substances and [[Char (chemistry)|char]]s. Cracking feedstocks into liquid and volatile compounds, and polymerising, or the forming of chars and solids, may both occur in the same process, and any class of the products might be of commercial interest.

Currently the major industrial application of destructive distillation is to [[coal]].<ref>{{cite book |last=Lunge |first=George |title=Coal-tar and ammonia |publisher=Gurney and Jackson |year=1887 |url=https://archive.org/details/coaltarandammon00lunggoog }}</ref><ref>{{cite book |last=Speight |first=James G. |title=The Refinery of the Future |publisher=William Andrew |year=2010 |isbn=978-0-8155-2041-2 }}</ref>

Historically the process of destructive distillation and other forms of pyrolysis led to the discovery of many chemical compounds or elucidation of their structures before contemporary organic chemists had developed the processes to synthesise or specifically investigate the parent molecules. It was especially in the early days that investigation of the products of destructive distillation, like those of other destructive processes, played parts in enabling chemists to deduce the chemical nature of many natural materials.<ref>{{cite book |last1=Schorlemmer |first1=Carl |last2=Smithells |first2=Arthur |title=The rise and development of organic chemistry |publisher=Macmillan |year=1894 |url=https://archive.org/details/risedevelopmento00schorich }}</ref> Well known examples include the deduction of the structures of [[pyranose]]s and [[furanose]]s.<ref>I.L. Finar Organic Chemistry vol 1 ( 4th.ed.) Longmans 1963 plus I.L. Finar Organic Chemistry vol 2 ( 3rd.ed.) Longmans Green & Co. 1964 May be downloaded from: https://archive.org/details/OrganicChemistryVol1 plus https://archive.org/details/OrganicChemistryVol2</ref>