Suprafaciální a antarafaciální

Suprafaciální (Woodwardovův–Hoffmannův symbol s) a antarafaciální (Woodwardův-Hoffmannův symbol a) jsou pojmy, které označují vzájemný vztah dvou chemických vazeb současně vznikajících nebo zanikajících na reakčním centru nebo v jeho okolí.[1] Reakčním centrem zde může být atomový orbital p nebo hybridizovaný orbital spn- (Woodwardův-Hoffmannův symbol ω), konjugovaný systém (π) nebo i vazba sigma (σ).

  • Reakce probíhá suprafaciálně, pokud jsou do procesu zapojeny orbitaly na stejné straně π systému nebo samotného orbitalu. U vazby sigma to odpovídá účasti dvou „vnitřních“ nebo dvou „vnějších“ laloků vazby.
  • Reakce probíhá antarafaciálně, jestliže jsou do procesu zapojeny orbitaly na opačných stranách π systému nebo orbitalu. U vazby sigma to odpovídá účasti jednoho „vnitřního“ a jednoho „vnějšího“ laloku vazby.

Složky všech pericyklických reakcí, jako jsou například sigmatropní reakce, cykloadice a elektrocyklizace, lze rozdělit na suprafaciální a antarafaciální, konkrétní konfigurací reakce je určena stereochemie produktu. Antarafaciální topologie reakce obecně vede k obrácení stereochemie u [1, n]-sigmatropních reakcí a ke konrotaci u elektrocyklických reakcí, zatímco suprafaciální k jejímu zachování u [1, n]-sigmatropních reakcí, případně k disrotaci u reakcí elektrocyklických.

Příkladem je [1,3]-hydridový posun, kdy interagujícími orbitaly jsou 1s orbitaly allylového radikálu a vodíku. Suprafaciální posun je symetricky znemožněn, protože orbitaly mají opačná znaménka překryvů. Reakce neprobíhá ani antarafaciálně, protože by u příslušného meziproduktu bylo přítomno velké sterické napětí. Oproti tomu je [1,5]-hydridový posun symetricky povolený, probíhá suprafaciálně a je poměrně běžný.[2]

Reference

V tomto článku byl použit překlad textu z článku Antarafacial and suprafacial na anglické Wikipedii.

  1. ↑ IUPAC Gold Book definition [1]
  2. ↑ F. A. Carey, R. J. Sundberg, Advanced Organic Chemistry Part A ISBN 0-306-41087-7

Read other articles:

JO1

JO1ジェイオーワンJO1 pada bulan November 2023Informasi latar belakangAsalChiba, Jepang[1]GenreJ-Pop[2][3]K-Pop[3][4]Tahun aktif2020 (2020)–sekarangLabelLapone EntertainmentSitus webhttps://jo1.jpAnggota Issei Mamehara Junki Kono Keigo Sato Ren Kawashiri Ruki Shiroiwa Shion Tsurubo Sho Yonashiro Shosei Ohira Sukai Kinjo Syoya Kimata Takumi Kawanishi JO1 (ジェイオーワンcode: ja is deprecated , Jeiōwan) adalah grup vokal pria asal Je...

 

 

Festival Glastonbury

Festival GlastonburyStatusAktifJenisFestival musikFrekuensiTahunan(akhir pekan bulan Juni)LokasiPilton, Somerset, InggrisKoordinat51°09′18″N 2°35′10″W / 51.155°N 2.586°W / 51.155; -2.586Koordinat: 51°09′18″N 2°35′10″W / 51.155°N 2.586°W / 51.155; -2.586Tahun aktif53Acara pertama19 September 1970 (1970-09-19)PendiriMichael EavisTerakhir diadakan22 Juni 2016 (2016-06-22) – 26 Juni 2016 (2016-6-26)Acara beri...

 

 

Cináed mac Ailpín

Kenneth MacAlpinRaja PictBerkuasa841 atau 843 – 858 atau 859PendahuluMonarki didirikanPenerusDomnallInformasi pribadiKelahiran810Pulau Iona, SkotlandiaKematian13 Februari 858CinnbelachoirPemakamanIonaWangsaAlpinAyahAlpín mac EchdachAnakRincianConstantín, Raja PictÁed, Raja PictMáel Muire Cináed mac Ailpín (Gaelik Modern: Coinneach mac Ailpein), umumnya dianglisisasi menjadi Kenneth MacAlpin dan dalam daftar raja modern biasanya disebut Kenneth I (810 – 13 Februari 858), adalah raja ...

Smbat I Hetumian

King of the Armenian Kingdom of Cilicia This article is about the 13th century Cilician king. For others with similar names, see Smbat. A coin of Smbat. Legend: ՍՄԲԱ[Տ ԹԱԳԱԻՈՐ ՀԱՅՈՑ] (Smbat, king of the Armenians). Smbat (Armenian: Սմբատ; 1277 – c. 1310) was king of the Armenian Kingdom of Cilicia, ruling from 1296 to 1298. He was the son of Leo II of Armenia and Kyranna de Lampron and was part of the Hetoumid-family. Sempad seized the throne with the aid of his brothe...

 

 

Rogers Morton

American politician Rogers MortonCounselor to the PresidentIn officeFebruary 2, 1976 – April 1, 1976PresidentGerald FordPreceded byRobert T. HartmannJohn MarshSucceeded byRobert T. HartmannJohn Marsh22nd United States Secretary of CommerceIn officeMay 1, 1975 – February 2, 1976PresidentGerald FordPreceded byFrederick B. DentSucceeded byElliot Richardson39th United States Secretary of the InteriorIn officeJanuary 29, 1971 – April 30, 1975PresidentRichard NixonG...

 

 

Daftar bank di Guinea-Bissau

Artikel ini sebatang kara, artinya tidak ada artikel lain yang memiliki pranala balik ke halaman ini.Bantulah menambah pranala ke artikel ini dari artikel yang berhubungan atau coba peralatan pencari pranala.Tag ini diberikan pada Desember 2023. Daftar bank komersial di Guinea-Bissau[1] Banco Da Africa Ocidental Banco Da Uniao Banque Régionale de Solidarité Ecobank[2] Pranala luar Website of Central Bank of West African States Lihat pula Guinea Bissau Referensi ^ List of Lic...

1961–62 Creighton Bluejays men's basketball team

American college basketball season 1961–62 Creighton Bluejays men's basketball1962 NCAA Tournament, Sweet SixteenConferenceIndependentRecord21–5Head coachRed McManusHome arenaOmaha Civic AuditoriumSeasons← 1960–611962–63 → The 1961–62 Creighton Bluejays men's basketball team represented Creighton University during the 1961–62 NCAA Division I men's basketball season. The Bluejays, led by third year head coach John J. 'Red' McManus, played their home ...

 

 

قائمة مواقع التراث العالمي في أمريكا الجنوبية

هذه قائمة من مواقع التراث العالمي لليونسكو في أمريكا الجنوبية. أسطورة موقع؛ حسب الاسم المسجل رسميا [1] الموقع؛ على مستوى المدينة أو المستوى الإقليمي أو الإقليمي والعناصر الجغرافية المعايير؛ على النحو المحدد من قبل لجنة التراث العالمي [2] منطقة؛ في هكتار وفدان. إذا �...

 

 

Silang, Cavite

Peta menunjukkan lokasi Silang Untuk desa di Kabupaten Halmahera Selatan, Maluku Utara, lihat Silang, Bacan Timur, Halmahera Selatan. Silang (resmi: Municipality of Silang; bahasa Tagalog: Bayan ng Silang) adalah munisipalitas kelas 5 di Cavite bagian timur, Filipina. Menurut sensus penduduk tahun 2009, Silang berpenduduk 234.285 jiwa. Pembagian wilayah Secara administratif, Silang terbagi atas 67 barangay, yaitu: Adlas Balite I Balite II Balubad Batas Biga I Biluso Buho Bucal Bulihan Cab...

Omosessualità nel cinema

Questa voce o sezione sull'argomento storia del cinema è priva o carente di note e riferimenti bibliografici puntuali. Sebbene vi siano una bibliografia e/o dei collegamenti esterni, manca la contestualizzazione delle fonti con note a piè di pagina o altri riferimenti precisi che indichino puntualmente la provenienza delle informazioni. Puoi migliorare questa voce citando le fonti più precisamente. Derek Jarman Caro William Shakespeare, ho 14 anni e sono queer come te, studio arte e ...

 

 

Niní Marshall

Argentine comedian and actress (1903–1996) Niní MarshallBirth nameMarina Esther TravesoBorn(1903-06-01)June 1, 1903Buenos Aires, ArgentinaDiedMarch 18, 1996(1996-03-18) (aged 92)Buenos Aires, ArgentinaMediumFilm, music, theatreGenresCharacter comedySpouse Felipe Edelmann ​(m. 1924)​ Marcelo Salcedo ​(m. 1936)​ Carmelo Santiago Marina Esther Traveso (June 1, 1903 – March 18, 1996), known by her stage name Niní Marsha...

 

 

美国众议院

此條目需要补充更多来源。 (2021年7月4日)请协助補充多方面可靠来源以改善这篇条目，无法查证的内容可能會因為异议提出而被移除。致使用者：请搜索一下条目的标题（来源搜索：美国众议院 — 网页、新闻、书籍、学术、图像），以检查网络上是否存在该主题的更多可靠来源（判定指引）。 美國眾議院 United States House of Representatives第118届美国国会众议院徽章 众议院旗...

ريسكو (بطليوس)

ريسكو Risco  - بلدية -    الموقع الجغرافي تقسيم إداري البلد إسبانيا[1] المقاطعة بطليوس خصائص جغرافية إحداثيات 38°54′38″N 5°07′23″W / 38.910555555556°N 5.1230555555556°W / 38.910555555556; -5.1230555555556   [2] المساحة 39.5 كيلومتر مربع  الارتفاع 497 السكان التعداد السكاني 150 نس�...

 

 

Nihon Bijutsu Token Hozon Kyokai

Nihon Bijutsu Tōken Hozon Kyōkai日本美術刀剣保存協会The Japanese Sword Museum, where the headquarter office of the Foundation is located (Sumida-ku)AbbreviationNBTHKPronunciationNihon Bijutsu Tōken Hozon Kyōkai FormationApril 1, 2012TypePublic Interest Incorporated FoundationRegistration no.6011005003782PurposeContribution to the preservation of cultural heritage and promotion of Japanese culture.HeadquartersTokyo, JapanLocation1-12-9 Yokoami , Sumida-ku, TokyoOriginsN...

 

 

Abbazia di Farneta

Chiesa di Santa Maria AssuntaEsternoStato Italia RegioneToscana LocalitàCortona Coordinate43°13′34.61″N 11°52′15.71″E43°13′34.61″N, 11°52′15.71″E Religionecattolica Diocesi Arezzo-Cortona-Sansepolcro Inizio costruzioneEtà longobarda CompletamentoCitata nel 1014 Sito webwww.abbaziafarneta.it/ Modifica dati su Wikidata · Manuale La chiesa di Santa Maria Assunta, anche conosciuta come abbazia di Farneta dalla località in cui si trova, è un luogo di culto sito n...

حوار الحضارات

حوار الحضارات فكرة من أول من تكلم بها المفكر الفرنسي روجيه جارودي عبر نظريته الرائدة ومشروعه للجمع بين الحضارات المختلفة على أساس أرضية مشتركة للتفاهم على مستوى شعوب الأرض وسماه بـ' حوار الحضارات '.[1] طرح الرئيس الإيراني محمد خاتمي نظرية حوار الحضارات في سبتمبر/أيلول 1...

 

 

Leadenhall Street

Street in the City of London, England Leadenhall Street from Whittington Avenue in 2016 Leadenhall Street (/ˈlɛdənˌhɔːl/) is a street in the City of London. It is about 1⁄3-mile-long (0.54 km) and links Cornhill in the west to Aldgate in the east. It was formerly the start of the A11 road from London to Norwich, but that route now starts further east at Aldgate. Leadenhall Street has always been a centre of commerce. It connected the medieval market of Leaden Hall with Aldgat...

 

 

Jorge Negrete

Mexican actor and singer (1911–1953) 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: Jorge Negrete – news · newspapers · books · scholar · JSTOR (January 2013) (Learn how and when to remove this message) In this Spanish name, the first or paternal surname is Negrete and the second or maternal famil...

Bramberģe Manor

Manor house in Latvia Bramberģe ManorZemgale, Latvia Bramberģe ManorCoordinates56°34′46.2″N 23°35′08.6″E / 56.579500°N 23.585722°E / 56.579500; 23.585722TypeManor Bramberģe Manor (Latvian: Bramberģes muiža, German: Brandenburg[1]) is a manor in Bramberģe, Glūda parish, Jelgava Municipality in the historical region of Zemgale, in Latvia.[2] History The manor complex with the park was formed in the end of 16th century. In 1645 Duke Jaco...

 

 

Nicolae Timofti

Nicolae Timofti Nicolae Timofti (sinh ngày 22 tháng 12 năm 1948) là một chính trị gia và luật sư Moldova, là Tổng thống Moldova kể từ 23 tháng 3 năm 2012. Trước đây ông từng là người đứng đầu của Hội đồng Thẩm phán tối cao của Moldova. Ông được bầu làm Chủ tịch quốc hội ngày 16 tháng 3 năm 2012. Tiểu sử Nicolae Timofti sinh năm 1948 ở Ciutuleşti, Cộng hòa xã hội chủ nghĩa Moldova, Liên Xô, trong gia ...