Borinic acid

The IUPAC name borinic acid is a unique name for the acid.{{cite book |last1=Connelly |first1=Neil G. |last2=Damhus |first2=Ture |last3=Hartshorn |first3=Richard M. |author4=Alan T. Hutton |title=Nomenclature of Inorganic Chemistry |year=2005| publisher=International Union of Pure and Applied Chemistry |isbn=0-85404-438-8 |page=127| chapter=Table IR-8.1 Acceptable common names}} The anhydrides are named diboroxanes, H₂BOBH₂, as the base compound and H being able to be substituted, e.g. tetraethyldiboroxane, as the anhydride for diethylborinic acid. Organic naming standard in the Bluebook allows skeletal replacement naming where the name is shorter, 3-borapentan-3-ol versus diethyl borinic acid. The grouping -BH-O-BH₂ is called diboroxanyl. Substituting sulfur for oxygen gives borinothioic acid (H₂BSH). (Dimethylboranyl)oxy is used for the group (CH₃)₂B-O− and methyl(hydroxy)boranyl for the grouping CH₃B(OH)-.

There are several ways to produce substituted borinic acids.

Firstly borinic acids can be made from oxidizing trialkylborane starting materials (R₃B) with exposure to moist air, or treatment with iodine, which makes a dialkyliodoborane (R₂BI). Hydrolysis then results in the boronic acid (R₂BOH). Trialkylborates [(RO)₃B] or trialkoxyboroxine [(ROBO)₃] can be reduced to borinic acid by us of a Grignard reagent. Grignard reagents can also reduce a boronic ester [RB(OR')₂] to a borinic ester.

:Bu₃B + N2CHCOR → BuCH=C(R)OBBu₂

:Bu₃B + CH2=CHCOCH₃ → BuCH₂CH=C(CH₃)OBBu₂

:RCOC₂H₅ + R₂BOTf → RC(OBR₂)=CHCH₃

::(Tf = Trifluoromethanesulfonate)

(Z)-Enolates give syn aldol product when reacted with an aldehyde, whereas (E)-enolates give and anti aldol products.

Dialkyl boron chloride (R₂BCl) with tertiary amine react with ketones to form an enol borinate.{{cite web|url=http://www.dtic.mil/dtic/Ftr/fulltext/u2/a209988.pdf|archive-url=https://web.archive.org/web/20160303220248/http://www.dtic.mil/dtic/Ftr/fulltext/u2/a209988.pdf|archive-date=March 3, 2016|title=Major Effect of the Leaving Group in Dialkyl Boron Chlorides and Triflates in COntrolling the Stereoscopic COnversion of Ketones into Either [E] or [Z]- Enol Borinates|last=Brown|first=Herbert C|author2=Rhaj K. Dhar|date=March 16, 1989|access-date=25 September 2013}}

A trialkoxyborane can react with lithium containing organic molecules to eliminate lithium and one or two alkoxy groups to make boronic and borinic esters.{{cite web|url=http://www.chemspecevents.com/europe/images/uploads/chemsource/10-5_Delbrayelle.pdf|title=Boronic Acids Manufacture at Industrial Scale|last=Delbrayelle|first=Dominique|date=15 June 2010|access-date=5 October 2013|archive-url=https://web.archive.org/web/20130628012416/http://www.chemspecevents.com/europe/images/uploads/chemsource/10-5_Delbrayelle.pdf|archive-date=28 June 2013}}

Purification of the mixtures that result from the reactions is required, as often boronic esters will also be produced and mixed in with the borinic esters. The method of Letsinger is to dissolve the mixture in ether and precipitate the borinic ester by forming a complex with ammonia. Treatment with ethanolamine ends up making an aminoetylborinate.

A wide variety of borinic acids, anhydrides ((R₂B)₂O), and esters (R₂BO{{prime|R}}) are known.{{cite patent|country=US|number=20020161230|invent1=Erbes, Michael|invent2=Forstinger, Klaus|invent3=Meudt, Andreas|status=Abandoned|title=Process for preparing boronic and borinic acids|pubdate=31 Oct 2002|fdate=28 Feb 2002|assign=Clariant GmbH|url=https://patents.google.com/patent/US20020161230}}{{cite thesis|url=http://ufdcimages.uflib.ufl.edu/UF/00/09/15/96/00001/Binder1.pdf|title=Boroxines: Their Reactions and Ring Stability|last=Povlock|first=Thomas Paul|degree=PhD|publisher=UFl|date=August 1960|access-date=5 October 2013|archive-date=5 March 2016|archive-url=https://web.archive.org/web/20160305011944/http://ufdcimages.uflib.ufl.edu/UF/00/09/15/96/00001/Binder1.pdf|url-status=dead}}

File:2-Aminoethoxydiphenyl borate 3D spacefill.png

2-Aminoethoxydiphenyl borate (2-APB) inhibits transient receptor potential channels.{{cite book|title=Carboxylic Acids—Advances in Research and Application|url=https://books.google.com/books?id=dpCfvweP9uUC&pg=PA93|page=93|year=2012| publisher=ScholarlyEditions |isbn=978-1-4649-9392-3}} This kind of inhibition, particularly inhibition of TRPM7, is being studied to find treatments for prostate cancer. 2-APB can work as a catalyst to add an alkyl group from an alkyl halide to a polyol or carbohydrate that contains a cis-vicinal diol to a precise position. It does this by first combining with the two hydroxy groups to make a ring containing OCCOB⁻.{{cite journal|last=Chan|first=Lina|author2=Taylor, Mark S.|title=Regioselective Alkylation of Carbohydrate Derivatives Catalyzed by a Diarylborinic Acid Derivative|journal=Organic Letters|date=17 June 2011|volume=13|issue=12|pages=3090–3093|doi=10.1021/ol200990e|pmid=21591630}} It can also calatlyse acid chloride or chloroformate reaction a specific region of the diol.{{cite journal|last=Lee|first=Doris|author2=Taylor, Mark S.|title=Borinic Acid-Catalyzed Regioselective Acylation of Carbohydrate Derivatives|journal=Journal of the American Chemical Society|date=23 March 2011|volume=133|issue=11|pages=3724–3727|doi=10.1021/ja110332r|pmid=21355584|bibcode=2011JAChS.133.3724L }}

Diphenylborinic acid was discovered in 1894 by Michaelis who produced it by hydrolyzing the chloride. Letsinger determined its properties in 1955.{{cite web|url=http://ufdcimages.uflib.ufl.edu/UF/00/09/15/96/00001/Binder1.pdf|title=Boroxines: Their Reactions and Ring Stability|last=Povlock|first=Thomas Paul|date=August 1960|access-date=5 October 2013|archive-date=5 March 2016|archive-url=https://web.archive.org/web/20160305011944/http://ufdcimages.uflib.ufl.edu/UF/00/09/15/96/00001/Binder1.pdf|url-status=dead}}

Diphenylborinic acid has an extra high affinity for catechols compared with carbohydrates.{{cite journal|last=Chudzinski|first=Michael G.|author2=Chi, Yuechuan |author3=Taylor, Mark S. |title=Borinic Acids: A Neglected Class of Organoboron Compounds for Recognition of Diols in Aqueous Solution|journal=Australian Journal of Chemistry|date=1 January 2011|volume=64|issue=11|page=1466|doi=10.1071/CH11294}}

Diphenylborinic acid can catalyse the condensation of pyruvic acids with aldehydes to yield substituted isotetronic acid.{{cite journal|last=Lee|first=Doris|author2=Newman, Stephen G. |author3=Taylor, Mark S. |title=Boron-Catalyzed Direct Aldol Reactions of Pyruvic Acids|journal=Organic Letters|date=3 December 2009|volume=11|issue=23|pages=5486–5489|doi=10.1021/ol902322r|pmid=19904926}}

Diphenylborinic acid is an inhibitor of several enzymes such as α-chymotrypsin, subtilisin BPN', and trypsin.{{cite journal|last=Steiner|first=Steven J.|author2=Bien, Jeffrey T. |author3=Smith, Bradley D. |title=Diphenylborinic acid is a strong inhibitor of serine proteases|journal=Bioorganic & Medicinal Chemistry Letters|date=1 October 1994|volume=4|issue=20|pages=2417–2420|doi=10.1016/S0960-894X(01)80401-7}}

Borinate radicals (RR'BO^·) can be formed from peroxyborinate decomposition.{{cite book|title=Stable Radicals: Fundamentals and Applied Aspects of Odd-Electron Compounds|url=https://books.google.com/books?id=WuwW8QDuCKIC&pg=PT518|author=Robin Hicks|date=2 August 2011|publisher=John Wiley and Sons|page=518|isbn=978-1-119-95696-9}}

Other compounds include methoxy(dimethyl)borane, methoxy(methyl)boron, methoxy(methylidene)borane (with a C=B double bond).{{cite web|url=https://www.ncbi.nlm.nih.gov/pccompound?LinkName=pccompound_pccompound&cmd=Link&from_uid=138247|title=Similar compounds|access-date=4 October 2013}}

[C₅H₅BR]⁻ uses a B⁻ to be equivalent to carbon in an aromatic benzene like ring. This too is called borinate. The 1-methyl and 1-phenyl borinates can form some of the few organo-thallium(I) compounds.{{cite journal|last=Janiac|year=1997|title=(Organo) thallium (I) and (II) chemistry: syntheses, structures, properties and applications of subvalent thallium complexes with alkyl, cyclopentadienyl, arene or hydrotris (pyrazolyl) borate ligands|journal=Coordination Chemistry Reviews|volume=163|page=124|url=http://portal.uni-freiburg.de/janiak/veroffentlichungen/pdf/59.pdf/at_download/file | doi = 10.1016/s0010-8545(97)00011-8 }}

HB(C₆F₅)₂ + phosphino alcohol → ^tBu₂P⁺HCH₂C(CH₃)₂OB⁻H(C₆F5)₂ → H₂ + ^tBu₂PCH₂C(CH₃)₂OB(C₆F5)₂ and same for ^tBu₂PCH₂C(CF₃)₂OB(C₆F5)₂{{cite journal|last=Chapman|first=Andy M.|author2=Haddow, Mairi F. |author3=Orton, Jonathan P. H. |author4= Wass, Duncan F. |date=1 January 2010|title=Facile dihydrogen release from phosphino-borinate ester Lewis pairs|journal=Dalton Transactions|volume=39|issue=27|pages=6184–6|doi=10.1039/c0dt00513d|pmid=20544115}}

di-Tris(tert-butoxy)siloxy borinic acid HOB[OSi(O(t)Bu)₃]₂ can be made from tributoxyborate and tributoxysiloxane. It can form a very complex crystal with Cp₂Zr(Me)[OB[OSi(O(t)Bu)₃]₂]₂.{{cite journal|last1=Fujdala|first1=KL|date=Feb 24, 2003|title=Tris(tert-butoxy)siloxy derivatives of boron, including the boronous acid HOB[OSi(O(t)Bu)(3)](2) and the metal (siloxy)boryloxide complex Cp(2)Zr(Me)OB[OSi(O(t)Bu)(3)](2): a remarkable crystal structure with 18 independent molecules in its asymmetric unit|journal=Inorganic Chemistry|volume=42|issue=4|pages=1140–1150|pmid=12588150|doi=10.1021/ic0205482|last2=Oliver|first2=A. G.|last3=Hollander|first3=F. J.|last4=Tilley|first4=T. D.}}

Diborinic acids have two RBOH groups linked together by an organic connection such as diphenyl or phenyl.{{cite journal|last=Suzuki|first=Akinobu Z.|author2=Shoichiro Ozaki, Jun-Ichi Goto Katsuhiko Mikishiba|date=15 Feb 2010|title=Synthesis of bisboron Compounds and their Strong Inhibitory Activity on Store-operated Calcium Entry|journal=Bioorganic & Medicinal Chemistry Letters|volume=20|issue=4|pages=1395–1398|doi=10.1016/j.bmcl.2009.12.108|pmid=20097561}}

1,1,1,3,3,3-Hexafluoroisopropylbis(pentafluorophenyl)borinate can greatly increase solubility of LiF by complexing the F⁻ anion.{{cite web|url=http://www.electrochem.org/dl/ma/204/Fpdfs/0298.pdf|title=Borinates: A New Family of Anion Complexing Agents|last=McBreen|first=J.|author2=H. S. Lee|author3=X. Q. Yang|year=2003|publisher=The Electrochemical Society, Inc.|access-date=25 September 2013}} This has potential to improve lithium batteries.

Borinic esters are being researched as bacterial growth inhibitors{{cite journal|last=Bailey|first=P. J.|author2=G Cousins |author3=G A Snow |author4=A J White |date=April 1980|title=Boron-containing antibacterial agents: effects on growth and morphology of bacteria under various culture conditions|journal=Antimicrobial Agents and Chemotherapy|publisher=American Society for Microbiology|volume=17|issue=4|pages=549–553|pmc=283830|doi=10.1128/aac.17.4.549|pmid=6994634}} due to their ability to disable some bacterial enzymes such as menaquinone methyltransferase and CcrM.{{cite journal|vauthors=Benkovic SJ, Baker SJ, Alley MR, Woo YH, Zhang YK, Akama T, Mao W, Baboval J, Rajagopalan PT, Wall M, Kahng LS, Tavassoli A, Shapiro L |title=Identification of Borinic Esters as Inhibitors of Bacterial Cell Growth and Bacterial Methyltransferases, CcrM and MenH|journal=Journal of Medicinal Chemistry|date=1 November 2005|volume=48|issue=23|pages=7468–7476|doi=10.1021/jm050676a|pmid=16279806}} This may result in development of treatments for topical application on skin.{{cite journal |vauthors=Baker SJ, Akama T, Zhang YK, Sauro V, Pandit C, Singh R, Kully M, Khan J, Plattner JJ, Benkovic SJ, Lee V, Maples KR |title=Identification of a novel boron-containing antibacterial agent (AN0128) with anti-inflammatory activity, for the potential treatment of cutaneous diseases |journal=Bioorg. Med. Chem. Lett. |volume=16 |issue=23 |pages=5963–7 |year=2006 |pmid=16997550 |doi=10.1016/j.bmcl.2006.08.130 }}

{{Reflist}}

• {{cite journal|last=Dimitrijević|first=Elena|author2=Taylor, Mark S.|title=Organoboron Acids and Their Derivatives as Catalysts for Organic Synthesis|journal=ACS Catalysis|date=3 May 2013|volume=3|issue=5|pages=945–962|doi=10.1021/cs4000848}} Review of use borinic acids as a catalyst
• {{cite journal|last=Roth|first=HJ|author2=Miller, B|title=Synthesis of Phenyl- and Thienyl-Substituted Boronic and Borinic Acids|journal=Archiv der Pharmazie|date=September 1964|volume=297|issue=9|pages=513–523|pmid=14341914|doi=10.1002/ardp.19642970902|s2cid=95181696}}

{{commons category|Borinate esters}}

{{Boron compounds}}

Category:Organoboron compounds