Editing Benzoic acid (section)

== Production ==

=== Industrial preparations ===
Benzoic acid is produced commercially by [[partial oxidation]] of [[toluene]] with [[oxygen]]. The process is catalyzed by [[cobalt]] or [[manganese]] [[naphthenate]]s. The process uses abundant materials, and proceeds in high yield.<ref>{{cite book|last1=Wade|first1=Leroy G.|title=Organic Chemistry|date=2014|publisher=Pearson Education Limited|location=Harlow|isbn=978-1-292-02165-2|page=985|edition=Pearson new international |ref=OrgChem}}</ref>
:[[Image:Benzoic acid-chemical-synthesis-1.svg|class=skin-invert-image|center|toluene oxidation]]

The first industrial process involved the reaction of [[benzotrichloride]] (trichloromethyl benzene) with [[calcium hydroxide]] in water, using [[iron]] or iron salts as [[catalyst]]. The resulting [[calcium benzoate]] is converted to benzoic acid with [[hydrochloric acid]]. The product contains significant amounts of [[Halogenation|chlorinated]] benzoic acid derivatives. For this reason, benzoic acid for human consumption was obtained by dry distillation of [[Benzoin (resin)|gum benzoin]]. Food-grade benzoic acid is now produced synthetically.

=== Laboratory synthesis ===
Benzoic acid is cheap and readily available, so the laboratory synthesis of benzoic acid is mainly practiced for its pedagogical value. It is a common undergraduate preparation.

Benzoic acid can be purified by [[Recrystallization (chemistry)|recrystallization]] from water because of its high solubility in hot water and poor solubility in cold water. The avoidance of organic solvents for the recrystallization makes this experiment particularly safe. This process usually gives a yield of around 65%.<ref>{{cite book | title = Purification of Laboratory Chemicals | url = https://archive.org/details/purificationofla0000perr_n7w5 | url-access = registration | edition = 3rd |author1=D. D. Perrin |author2=W. L. F. Armarego | publisher = Pergamon Press | pages = [https://archive.org/details/purificationofla0000perr_n7w5/page/94 94] | year = 1988 | isbn = 978-0-08-034715-8}}</ref>

==== By hydrolysis ====
Like other [[nitrile]]s and [[amide]]s, [[benzonitrile]] and [[benzamide]] can be hydrolyzed to benzoic acid or its conjugate base in acid or basic conditions.

==== From Grignard reagent====
[[Bromobenzene]] can be converted to benzoic acid by "carboxylation" of the intermediate [[phenylmagnesium bromide]].<ref>{{cite book|title=Introduction to Organic Laboratory Techniques: A Small Scale Approach|author=Donald L. Pavia|year=2004|publisher=Thomson Brooks/Cole|isbn=978-0-534-40833-6|pages=312–314}}</ref> This synthesis offers a convenient exercise for students to carry out a [[Grignard reaction]], an important class of [[carbon–carbon bond]] forming reaction in organic chemistry.<ref>{{cite journal|last=Shirley|first=D. A.|year=1954|title=The Synthesis of Ketones from Acid Halides and Organometallic Compounds of Magnesium, Zinc, and Cadmium|journal=[[Org. React.]]|volume=8|pages=28–58}}</ref><ref>{{cite book|last=Huryn|first=D. M.|year=1991|title=Comprehensive Organic Synthesis, Volume 1: Additions to C&mdash;X π-Bonds, Part 1|pages=49–75|chapter=Carbanions of Alkali and Alkaline Earth Cations: (ii) Selectivity of Carbonyl Addition Reactions|editor1-last=Trost|editor1-first=B. M.|editor2-last=Fleming|editor2-first=I.|isbn=978-0-08-052349-1|editor1-link=Barry Trost|editor2-link=Ian Fleming (chemist)|publisher= [[Elsevier Science]]|doi= 10.1016/B978-0-08-052349-1.00002-0}}</ref><ref>{{cite web|publisher=Portland Community College|title=The Grignard Reaction. Preparation of Benzoic Acid|url=http://spot.pcc.edu/~chandy/242/PreparationofBenzoicAcid.pdf|access-date=2015-03-12|url-status=dead|archive-url=https://web.archive.org/web/20150226115836/http://spot.pcc.edu/~chandy/242/PreparationofBenzoicAcid.pdf|archive-date=26 February 2015}}></ref><ref>{{cite web|publisher=University of Wisconsin-Madison|title=Experiment 9: Synthesis of Benzoic Acid via Carbonylation of a Grignard Reagent|url=http://www.chem.wisc.edu/courses/342/Fall2004/Experiment_9.pdf|access-date=12 March 2015|archive-url=https://web.archive.org/web/20150923202908/http://www.chem.wisc.edu/courses/342/Fall2004/Experiment_9.pdf|archive-date=23 September 2015|url-status=dead}}</ref><ref>{{cite web|publisher=Towson University|title=Experiment 3: Preparation of Benzoic Acid|url=http://pages.towson.edu/jdiscord/WWW/332_Lab_Info/332LabsIRPMR/Expt3Grignard.pdf|access-date=2015-03-12|url-status=dead|archive-url=https://web.archive.org/web/20150413011353/http://pages.towson.edu/jdiscord/www/332_lab_info/332labsirpmr/expt3grignard.pdf |archive-date=13 April 2015 |df=dmy-all }}></ref>

==== Oxidation of benzyl compounds====
[[Benzyl alcohol]]<ref>{{Cite journal|last1=Santonastaso|first1=Marco|last2=Freakley|first2=Simon J.|last3=Miedziak|first3=Peter J.|last4=Brett|first4=Gemma L.|last5=Edwards|first5=Jennifer K.|last6=Hutchings|first6=Graham J.|date=2014-11-21|title=Oxidation of Benzyl Alcohol using in Situ Generated Hydrogen Peroxide|journal=Organic Process Research & Development|volume=18|issue=11|pages=1455–1460|doi=10.1021/op500195e|issn=1083-6160}}</ref> and [[benzyl chloride]] and virtually all benzyl derivatives are readily oxidized to benzoic acid.