Collins reagent

This article is about the oxidizing reagent. For the oxidation reaction, see Collins oxidation.
Collins reagent
Names
IUPAC name
Pyridine - trioxochromium (2:1)
Other names
Dipyridine chromium(VI) oxide[1]
Identifiers
3D model (JSmol)
ChemSpider
  • InChI=1S/2C5H5N.Cr.3O/c2*1-2-4-6-5-3-1;;;;/h2*1-5H;;;;
    Key: NPRDHMWYZHSAHR-UHFFFAOYSA-N
  • InChI=1/2C5H5N.Cr.3O/c2*1-2-4-6-5-3-1;;;;/h2*1-5H;;;;/r2C5H5N.CrO3/c2*1-2-4-6-5-3-1;2-1(3)4/h2*1-5H;
    Key: NPRDHMWYZHSAHR-RGHLCDNPAM
  • c1ccncc1.c1ccncc1.O=[Cr](=O)=O
Properties
C10H10CrN2O3
Molar mass 258.194
Appearance Red crystals[1]
Density 1.565 g/cm3
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Collins reagent is the complex of chromium(VI) oxide with pyridine in dichloromethane.[2] This metal-pyridine complex, a red solid, is used to oxidize primary alcohols to the corresponding aldehydes and secondary alcohols to the corresponding ketones. This complex is a hygroscopic orange solid.[1]

Synthesis and structure

The complex is produced by treating chromium trioxide with pyridine.[2] The complex is diamagnetic. According to X-ray crystallography, the complex is 5-coordinate with mutually trans pyridine ligands. The Cr-O and Cr-N distances are respectively 163 and 215 picometers.[3]

In terms of history, the complex was first produced by Sisler et al.[4]

Reactions

Collins reagent is especially useful for oxidations of acid sensitive compounds. Primary and secondary alcohols are oxidized respectively to aldehydes and ketones in yields of 87-98%.[5]

Like other oxidations by Cr(VI), the stoichiometry of the oxidations is complex because the metal undergoes 3e reduction and the substrate is oxidized by 2 electrons:

3 RCH2OH + 2 CrO3(pyridine)2 → 3 RCHO + 3 H2O + Cr2O3 + 4 pyridine

The reagent is typically used in a sixfold excess. Methylene chloride is the typical solvent, with the solubility of 12.5 g/100 ml.

The application of this reagent to oxidations was discovered by G. I. Poos, G. E. Arth, R. E. Beyler and L.H. Sarett in 1953. It was popularized by J. C. Collins several years later.[6]

Other reagents

Collins reagent can be used as an alternative to the Jones reagent and pyridinium chlorochromate (PCC) when oxidizing secondary alcohols to ketones. PCC and pyridinium dichromate (PDC) oxidations have largely supplanted Collins oxidation.[1]

Safety and environmental aspects

The solid is flammable.[1] Generally speaking chromium (VI) compounds are carcinogenic.

References

  1. ^ a b c d e Fillmore Freeman (2001). "Dipyridine Chromium(VI) Oxide". e-EROS Encyclopedia of Reagents for Organic Synthesis. doi:10.1002/047084289X.rd452m. ISBN 0471936235.
  2. ^ a b J. C. Collins, W.W. Hess (1972). "Aldehydes from Primary Alcohols by Oxidation with Chromium Trioxide: Heptanal". Organic Syntheses. 52: 5. doi:10.15227/orgsyn.052.0005.
  3. ^ Cameron, T Stanley; Clyburne, Jason AC; Dubey, Pramod K.; Grossert, J Stuart; Ramaiah, K.; Ramanatham, J.; Sereda, Sergei V. (2003). "Compounds of chromium(VI): The Pyridine.Chromic Anhydride Complex, Benzimidazolinium Dichromate, and Three 2-Alkyl-1H-benzimidazolinium Dichromates". Canadian Journal of Chemistry. 81 (6): 612–619. doi:10.1139/v03-042.
  4. ^ Sisler, Harry H.; Bush, Jack D.; Accountius, Oliver E. (1948). "Addition Compounds of Chromic Anhydride with Some Heterocyclic Nitrogen Bases". Journal of the American Chemical Society. 70 (11): 3827–3830. doi:10.1021/ja01191a085. PMID 18102959.
  5. ^ Ronald Ratcliffe and Ronald Rodehorst (1970). "Improved Procedure for Oxidations with the Chromium Trioxide-Pyridine Complex". J. Org. Chem. 35 (11): 4000–4001. doi:10.1021/jo00836a108.
  6. ^ J. C. Collins, W. W. Hess and F. J. Frank (1968). "Dipyridine-chromium(VI) oxide oxidation of alcohols in dichloromethane". Tetrahedron Lett. 9 (30): 3363–3366. doi:10.1016/S0040-4039(00)89494-0.

Read other articles:

Luis Enrique

Untuk orang lain dengan nama yang sama, lihat Luis Enrique (disambiguasi). Nama ini menggunakan cara penamaan Spanyol: nama keluarga pertama atau paternalnya adalah Martínez dan nama keluarga kedua atau maternalnya adalah García. Luis Enrique Enrique pada 2020Informasi pribadiNama lengkap Luis Enrique Martínez García[1]Tanggal lahir 8 Mei 1970 (umur 53)[1]Tempat lahir Gijón, Spanyol[1]Tinggi 185 cm (6 ft 1 in)[1]Posisi bermain Gela...

 

الدوري المنغولي لكرة القدم 2000

الدوري المنغولي لكرة القدم 2000 تفاصيل الموسم الدوري المنغولي لكرة القدم  البلد منغوليا  البطل نادي إركيم  الدوري المنغولي لكرة القدم 1999  الدوري المنغولي لكرة القدم 2001  تعديل مصدري - تعديل   الدوري المنغولي لكرة القدم 2000 هو موسم من الدوري المنغولي لكرة القدم. �...

 

2017 Swiss Open Gstaad – Doubles

This article has multiple issues. Please help improve it or discuss these issues on the talk page. (Learn how and when to remove these template messages) This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed.Find sources: 2017 Swiss Open Gstaad – Doubles – news · newspapers · books · scholar · JSTOR (July 2017) (Learn how and...

Baltimore

Largest city in Maryland, U.S. This article is about the city in Maryland. For other uses, see Baltimore (disambiguation). Independent city in Maryland, United StatesBaltimoreIndependent cityThe Inner Harbor skylineFell's PointOriole Park at Camden YardsEmerson TowerWashington and Lafayette MonumentsNational Aquarium FlagSealNicknames: Charm City;[1] B'more;[2] Mobtown[3]Motto(s): The Greatest City in America,[1] Get in on it.,[1] Believe[...

 

Apollo 4

First test flight of the Apollo Saturn V rocket Apollo 4The first flight of a Saturn V launch vehicleMission typeUncrewed Earth orbital CSM flight (A)OperatorNASACOSPAR ID1967-113A (command and service modules)1967-113B (S-IVB)[1]SATCAT no.3032Mission duration8 hours, 36 minutes, 59 secondsOrbits completed3 Spacecraft propertiesSpacecraftApollo CSM-017Apollo LTA-10RManufacturerNorth American RockwellLaunch mass36,856 kilograms (81,253 lb) Start of missionLaunch dateNove...

 

Associazione Sportiva Rieti 1946-1947

Questa voce sull'argomento stagioni delle società calcistiche italiane è solo un abbozzo. Contribuisci a migliorarla secondo le convenzioni di Wikipedia. Segui i suggerimenti del progetto di riferimento. Voce principale: Football Club Rieti. Associazione Sportiva RietiStagione 1946-1947Sport calcio Squadra Rieti Allenatore Ermes Borsetti Presidente Florido Floridi Serie B6º posto nel girone C. Maggiori presenzeCampionato: Borsetti (39) Miglior marcatoreCampionato: Borsetti, Ceca...

Aurora Pro Patria 1919 2011-2012

Voce principale: Aurora Pro Patria 1919. Aurora Pro Patria 1919Stagione 2011-2012Sport calcio Squadra Pro Patria Allenatore Giovanni Cusatis Presidente Pietro Vavassori Seconda Divisione7º posto Coppa Italia1º turno Coppa Italia Lega Pro1º turno eliminazione diretta Maggiori presenzeCampionato: Bruccini (36) Miglior marcatoreCampionato: M. Serafini (19) StadioCarlo Speroni (4.627) Maggior numero di spettatori1 700 vs. Mantova[1] Minor numero di spettatori750 vs. Sambonif...

 

Eliaquim Mangala

Eliaquim Mangala Mangala bermain untuk Porto pada 2013Informasi pribadiNama lengkap Eliaquim Hans MangalaTanggal lahir 13 Februari 1991 (umur 33)Tempat lahir Colombes, PrancisTinggi 1,88 m (6 ft 2 in)[1]Posisi bermain BekInformasi klubKlub saat ini Valencia(pinjaman dari Manchester City)Nomor 5Karier junior1996–2002 AC Lustin2002–2004 CS Wépionnais2004–2008 NamurKarier senior*Tahun Tim Tampil (Gol)2008–2011 Standard Liège 77 (2)2011–2014 Porto 51 (6)20...

 

Associazione Calcio Reggiana 1979-1980

Voce principale: Associazione Calcio Reggiana 1919. AC ReggianaStagione 1979-1980Sport calcio Squadra Reggiana Allenatore Franco Marini Presidente Franco Vacondio Serie C111º nel girone A Coppa Italia SemiprofessionistiOttavi di finale Maggiori presenzeCampionato: Erba e Pagani (33) Miglior marcatoreCampionato: Mossini (8) StadioMirabello Abbonati1 300 Maggior numero di spettatori6 542 vs Cremonese(27 gennaio 1980) Minor numero di spettatori1 500 vs Novara(18 maggio 1980...

Harta Karun

Buyung, benda peninggalan masyarakat Lidia yang ditemukan di dekat Uşak Harta Kârun adalah nama yang diberikan kepada koleksi artefak yang terdiri atas 363 barang berharga peninggalan masyarakat Lidia dari sekitar abad ke-7 Pramasehi dan ditemukan di Provinsi Uşak, kawasan barat Turki, yang diperebutkan lewat jalur hukum oleh Turki dan Museum Seni Rupa Metropolitan New York antara tahun 1987 sampai 1993, dan akhirnya dipulangkan ke Turki pada tahun 1993 sesudah pihak Museum Seni Rupa Metro...

 

Satyricon

This article is about the book. For other uses, see Satyricon (disambiguation). Latin work of fiction attributed to Petronius Satyricon A modern illustration of the SatyriconAuthorPetroniusCountryRoman EmpireLanguageLatinPublisherVariousPublication dateLate 1st century AD The Satyricon, Satyricon liber (The Book of Satyrlike Adventures), or Satyrica,[1] is a Latin work of fiction believed to have been written by Gaius Petronius in the late 1st century AD, though the manuscript traditi...

 

ソー (オー＝ド＝セーヌ県)

Sceaux 行政国 フランス地域圏 (Région) イル＝ド＝フランス地域圏県 (département) オー＝ド＝セーヌ県郡 (arrondissement) アントニー郡小郡 (canton) 小郡庁所在地INSEEコード 92071郵便番号 92330市長（任期） フィリップ・ローラン（2008年-2014年）自治体間連合 (fr) メトロポール・デュ・グラン・パリ人口動態人口 19,679人（2007年）人口密度 5466人/km2住民の呼称 Scéens地理座標 北緯48度4...

Hamilton, Montana

City in Montana, United States City in Montana, United StatesHamiltonCityDowntown HamiltonLocation of Hamilton, MontanaCoordinates: 46°14′54″N 114°9′35″W / 46.24833°N 114.15972°W / 46.24833; -114.15972CountryUnited StatesStateMontanaCountyRavalliGovernment • MayorDominic A Farrenkopf [1]Area[2] • Total2.60 sq mi (6.73 km2) • Land2.54 sq mi (6.58 km2) • Water0.06...

 

Shading

Depicting depth through varying levels of darkness This article is about shading in computer graphics. For the GPU technology that performs these techniques, see Shader. For other uses, see Shade. This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed.Find sources: Shading – news · newspapers · books · scholar · JSTOR (May 2007)...

 

Державний комітет телебачення і радіомовлення України

Державний комітет телебачення і радіомовлення України (Держкомтелерадіо) Приміщення комітетуЗагальна інформаціяКраїна  УкраїнаДата створення 2003Керівне відомство Кабінет Міністрів УкраїниРічний бюджет 1 964 898 500 ₴[1]Голова Олег НаливайкоПідвідомчі ор...

中華民國國軍中的中共間諜列表

 本表是動態列表，或許永遠不會完結。歡迎您參考可靠來源來查漏補缺。 潛伏於中華民國國軍中的中共間諜列表收錄根據公開資料來源，曾潛伏於中華民國國軍、被中國共產黨聲稱或承認，或者遭中華民國政府調查審判，為中華人民共和國和中國人民解放軍進行間諜行為的人物。以下列表以現今可查知時間為準，正確的間諜活動或洩漏機密時間可能早於或晚於以下所歸�...

 

Amélie Beaury-Saurel

Amélie Beaury-SaurelLahirAmélie Beaury1849 (1849)Barcelona, SpanyolMeninggal30 Mei 1924(1924-05-30) (umur 74–75)KebangsaanPrancisDikenal atasLukisan Amélie Beaury-Saurel (19 Desember 1849 – 30 Mei 1924) adalah seorang pelukis Perancis terkenal untuk potret. Life and career Lahir di Barcelona sebagai Amélie Beaury, ia menambahkan Saurel ke namanya sebagai pengakuan atas keluarga ibunya yang dapat melacak garis keturunan mereka hingga kaisar Bizantium pada abad ...

 

Redwall Limestone

Geologic formation in Arizona, USA Redwall LimestoneStratigraphic range: Early and early Late Mississippian[1][2]Redwall Limestone cliff, and upper platform of cliff extension (resting on very short Muav Limestone cliff), from Tower of Set, central Grand Canyon, adjacent Granite Gorge. The bottom of Redwall cliffs typically rest on sections of Temple Butte Formation-(locally), or attached sections of Muav Limestone cliffs (regionally exposed in Grand Canyon, elsewhere in Arizo...

علم الفلك الرصدي

جزء من سلسلة عنعلم الكون الفيزيائي الانفجار العظيمالفضاء الكوني عمر الكون تاريخ الكون التسلسل الزمني للانفجار العظيم بدايات الكون التضخم الكونيالتخليق النووي بعد الانفجار العظيم الخلفية الكونية لموجة جاذبية إشعاع الأمواج الصغرية للخلفية الكونيةإشعاع نيوترينوي للخلفي...

 

First Church and Parish in Dedham

First Church and Parish, Dedham MA The First Church and Parish in Dedham is a Unitarian Universalist congregation in Dedham, Massachusetts. It was the 14th church established in Massachusetts.[1] The current minister, Rev. Rali M. Weaver, was called in March 2007, settled in July, and is the first female minister to this congregation. History Dedham was first settled in 1635 and incorporated in 1636. On July 18, 1637, the Town voted to admit a group of very religious men that would r...