Allenlar: Versiyalar orasidagi farq

Vikipediya, ochiq ensiklopediya
Keyingi tahrir →
Kontent oʻchirildi Kontent qoʻshildi
VizualVikimatn
„Allenes“ sahifasi tarjima qilib yaratildi
(Farq yoʻq)

24-Noyabr 2022, 03:52 dagi koʻrinishi

Propadien, eng oddiy allen sifatida tanilgan

Organik kimyoda allenlar organik birikmalar bo'lib, ularda bitta uglerod atomi o'zining ikkita qo'shni uglerod markazining har biri bilan qo'sh bog'lanishga (C=C=C) ega. Allenlar to'plangan dienlar ham hisoblanadi. Ushbu sinfning asosiy birikmasi propadien bo'lib, allenlar sinifiga mansub. Allen tipidagi tuzilishga ega, ammo uchdan ortiq uglerod atomiga ega bo'lgan birikmalar kumulenlar deb ataladi.

Tarixi

Ko'p yillar davomida allenlar qiziqish sifatida qaralgan, ammo sintetik jihatdan foydasiz va ularni tayyorlash, ishlash qiyin deb hisoblangan[1][2]. Ma'lum bo'lishicha[3] allen, glutin kislotasining birinchi sintezi bo'lib, birikmalar sinfi mavjudligini isbotlash maqsadida[4][5] 1950 - 2012-yilgacha allenlar bo'yicha 300d an ortiq maqola chop etildi[6]. Bu birikmalar nafaqat qiziqarli oraliq mahsulotlar, balki sintetik jihatdan qimmatli maqsadlarda masalan, 150 dan ortiq tabiiy mahsulotlar allen yoki kumulen tarkibi bilan ma'lum.

Tuzilishi va xususiyatlari

Geometriya tuzilishi

Propadienning 3D ko'rinishi (allen)

Allenlarning markaziy uglerod atomi ikkita sigma bog' va ikkita pi bog' hosil qilib birikadi. Markaziy uglerod atomi sp-gibridlangan va ikkita uglerod atomi sp2 - gibridlangan. Uchta uglerod atomi tomonidan hosil qilingan bog'lanish burchagi 180° bo'lib, markaziy uglerod atomi uchun chiziqli geometriyani ko'rsatadi. Ikkita uglerod atomi tekis bo'lib, bu tekisliklar bir-biridan 90°ga farq qiladi. Tuzilish strukturasi metanga o'xshash shaklda "kengaytirilgan tetraedral" sifatida ham ko'rish mumkin, bu o'xshashlik ma'lum lotin molekulalarining stereokimyoviy tahlilida hosil bo'ladi.

Simmetriya tuzilishi

Allenlarning simmetriyasi va izomeriyasi uzoq vaqtdan beri organik kimyogarlarni hayratda qoldirdi. Allenlar uchun markaziy uglerod atomi orqali molekulasining ikkala uchida CH2 tekisligi 45°ga egilgan va ikkita ikki tomonlama aylanish o'qi mavjud. Shunday qilib, molekulani ikki qanotli pervanel deb hisoblash mumkin. C=C=C bogʻlanishlari orqali uchinchi ikki qavatli aylanish oʻqi oʻtadi. Shunday qilib, molekulalarning bu sinfi D2d nuqta guruhiga mansub. Simmetriyasi sababli dipol momentga ega emas, ya'ni u qutbsiz molekuladir.  

Kimyoviy va spektral xossalari

Allenlarning kimyoviy xossalari jihatidan boshqa alkenlardan ancha farq qiladi. Ajratilgan va konyugatsiyalangan dienlar bilan solishtirganda ular ancha barqaror emas. Allenlarni hosil bo'lish issiqligi, izomerik pentadienlar bilan solishtirganda 1,2-pentadien uchun 33,6 kkal/mol. 1.3-pentadien uchun esa 18,1 kkal/mol va 1,4-pentadien uchun 25,4 kkal/mol[7].

Allenlarning 13C NMR spektri sp-gibridlangan uglerod atomining signali bilan xarakterlanadi va 200-220 ppmda rezonanslanadi. Bundan farqli o'laroq, sp2-gibridlangan uglerod atomlari alkin va nitril uglerod atomlari uchun xos bo'lgan hududda 80 ppm atrofida rezonanslanadi, terminal allenning CH2 guruhining protonlari esa 4,5 ppm atrofida rezonanslanadi - bu vinillik protonning biroz yuqorisida ro'y beradi[8].

Allenlar boy siklo yuklanish kimyosiga ega, jumladan, [4+2] va [2+2] qoʻshilish usullari[9][10], hamda metallar tomonidan katalizlangan rasmiy siklo yuklanish jarayonlarida ishtirok etadi[11][12]. Shuningdek allenlar metallning katalizlangan gidrofunksionalizatsiya reaksiyalari uchun substrat bo'lib xizmat qiladi[13][14][15].

Sintezlanishi

Allenlar ko'pincha maxsus sintezni talab qilsa-da, propadien sanoatda keng miqyosda metilatsetilen bilan muvozanat aralashmasi sifatida ishlab chiqariladi.

<math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow class="MJX-TeXAtom-ORD"><mstyle displaystyle="true" scriptlevel="0"><mrow class="MJX-TeXAtom-ORD"><msubsup><mtext> </mtext><mrow class="MJX-TeXAtom-ORD"><mn> </mn></mrow></msubsup><mtext> </mtext><mrow class="MJX-TeXAtom-ORD"><mo> </mo></mrow><mtext> </mtext><mrow class="MJX-TeXAtom-ORD"><mo> </mo></mrow><msubsup><mtext> </mtext><mrow class="MJX-TeXAtom-ORD"><mn> </mn></mrow></msubsup><mrow class="MJX-TeXAtom-REL"><mover><mrow class="MJX-TeXAtom-OP MJX-fixedlimits"><mrow class="MJX-TeXAtom-ORD"><mpadded depth="0" height="0"><mrow class="MJX-TeXAtom-ORD"><mo stretchy="false"> </mo></mrow><mrow class="MJX-TeXAtom-ORD"><mo> </mo></mrow></mpadded></mrow></mrow><mrow class="MJX-TeXAtom-ORD"><mstyle displaystyle="false" scriptlevel="0"><mrow class="MJX-TeXAtom-ORD"><mrow class="MJX-TeXAtom-ORD"><mo> </mo></mrow><mrow class="MJX-TeXAtom-ORD"><mo stretchy="false"> </mo></mrow></mrow></mstyle></mrow></mover></mrow><msubsup><mtext> </mtext><mrow class="MJX-TeXAtom-ORD"><mn> </mn></mrow></msubsup><mtext> </mtext><mrow class="MJX-TeXAtom-ORD"><mo> </mo></mrow><mtext> </mtext><mrow class="MJX-TeXAtom-ORD"><mo> </mo></mrow><mtext> </mtext></mrow></mstyle></mrow><annotation encoding="application/x-tex"> </annotation></semantics></math>

MAPP gazi sifatida tanilgan ushbu aralashma savdo sifatida mavjud. 298 Kda bu reaksiyaning ΔG°si –1,9 kkal/mol, Kekv = 24,7ga mos keladi[16].

Sintezlangan birinchi allenni 1887-yilda Burton va Pechmann tomonidan penta-2,3-diendioik kislotasi yaratilgan. Biroq, strukturasi 1954-yilda aniqlangan[17].

Ko'pgina halqalar yoki halqa tizimlari yarim tizimli nomlar bilan ma'lum bo'lib, ular to'planmagan aloqalarning maksimal sonini o'z ichiga oladi. Yig'ilgan bog'lanishlarni (va shuning uchun skeletdan kutilganidan kamroq vodorod atomlarini) o'z ichiga olgan hosilalarni bir ma'noda belgilash uchun kichik deltadan ushbu atomdan to'plangan qo'sh aloqalar sonini ko'rsatadigan pastki belgisi bilan foydalanish mumkin, masalan, 8d2 -benzosiklonon. Bu nostandart valentlik holatlarini belgilash uchun l-konventsiya bilan birlashtirilishi mumkin, masalan, 2l 4 d 2 ,5l 4 d 2 -tieno[3,4-c]tiofen. [18]

Yana qarang

  • Uch yoki undan ortiq qo'shni uglerod-uglerod qo'sh bog'lari bo'lgan birikmalar kumulenlar deb ataladi.

Manbalar

  1. ↑ The Chemistry of the Allenes (vol. 1−3); Landor, S. R., Ed.; cademic Press: London, 1982.
  2. ↑ Taylor, David R. (1967-06-01). "The Chemistry of Allenes" (en). Chemical Reviews 67 (3): 317–359. doi:10.1021/cr60247a004. ISSN 0009-2665. https://pubs.acs.org/doi/abs/10.1021/cr60247a004. 
  3. ↑ Hoffmann-Röder, Anja; Krause, Norbert (2004-02-27). "Synthesis and Properties of Allenic Natural Products and Pharmaceuticals" (en). Angewandte Chemie International Edition 43 (10): 1196–1216. doi:10.1002/anie.200300628. ISSN 1433-7851. PMID 14991780. https://onlinelibrary.wiley.com/doi/10.1002/anie.200300628. 
  4. ↑ Burton, B. S.; von Pechmann, H. (January 1887). "Ueber die Einwirkung von Chlorphosphor auf Acetondicarbonsäureäther" (de). Berichte der Deutschen Chemischen Gesellschaft 20 (1): 145–149. doi:10.1002/cber.18870200136. https://onlinelibrary.wiley.com/doi/10.1002/cber.18870200136. 
  5. ↑ Jones, E. R. H.; Mansfield, G. H.; Whiting, M. C. (1954). "Researches on acetylenic compounds. Part XLVII. The prototropic rearrangements of some acetylenic dicarboxylic acids" (en). Journal of the Chemical Society (Resumed): 3208–3212. doi:10.1039/jr9540003208. ISSN 0368-1769. http://xlink.rsc.org/?DOI=jr9540003208. 
  6. ↑ Data from the Web of Science database.
  7. ↑ Informatics, NIST Office of Data and (1997) (en). Welcome to the NIST WebBook. doi:10.18434/T4D303. https://webbook.nist.gov/index.html.en-us.en. Qaraldi: 2020-10-17. Allenlar]]
  8. ↑ Pretsch, Ernö, 1942-. Structure determination of organic compounds : tables of spectral data, Bühlmann, P. (Philippe), 1964-, Badertscher, M., Fourth, Revised and Enlarged, Berlin: Springer, 2009. ISBN 978-3-540-93810-1. OCLC 405547697. 
  9. ↑ Alcaide, Benito; Almendros, Pedro; Aragoncillo, Cristina (2010-01-28). "Exploiting [2+2 cycloaddition chemistry: achievements with allenes"] (en). Chemical Society Reviews 39 (2): 783–816. doi:10.1039/B913749A. ISSN 1460-4744. PMID 20111793. https://pubs.rsc.org/en/content/articlelanding/2010/cs/b913749a. 
  10. ↑ Pasto, Daniel J. (January 1984). "Recent developments in allene chemistry" (en). Tetrahedron 40 (15): 2805–2827. doi:10.1016/S0040-4020(01)91289-X. https://linkinghub.elsevier.com/retrieve/pii/S004040200191289X. 
  11. ↑ Alcaide, Benito; Almendros, Pedro (August 2004). "The Allenic Pauson−Khand Reaction in Synthesis" (en). European Journal of Organic Chemistry 2004 (16): 3377–3383. doi:10.1002/ejoc.200400023. ISSN 1434-193X. http://doi.wiley.com/10.1002/ejoc.200400023. 
  12. ↑ Mascareñas, José L.; Varela, Iván; López, Fernando (2019-02-19). "Allenes and Derivatives in Gold(I)- and Platinum(II)-Catalyzed Formal Cycloadditions" (en). Accounts of Chemical Research 52 (2): 465–479. doi:10.1021/acs.accounts.8b00567. ISSN 0001-4842. PMID 30640446. PMC 6497370. //www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=6497370. 
  13. ↑ Zi, Weiwei; Toste, F. Dean (2016-08-08). "Recent advances in enantioselective gold catalysis" (en). Chemical Society Reviews 45 (16): 4567–4589. doi:10.1039/C5CS00929D. ISSN 1460-4744. PMID 26890605. https://pubs.rsc.org/en/content/articlelanding/2016/cs/c5cs00929d. 
  14. ↑ Lee, Mitchell; Nguyen, Mary; Brandt, Chance; Kaminsky, Werner; Lalic, Gojko (2017-12-04). "Catalytic Hydroalkylation of Allenes" (en). Angewandte Chemie International Edition 56 (49): 15703–15707. doi:10.1002/anie.201709144. PMID 29052303. 
  15. ↑ Kim, Seung Wook; Meyer, Cole C.; Mai, Binh Khanh; Liu, Peng; Krische, Michael J. (2019-10-04). "Inversion of Enantioselectivity in Allene Gas versus Allyl Acetate Reductive Aldehyde Allylation Guided by Metal-Centered Stereogenicity: An Experimental and Computational Study". ACS Catalysis 9 (10): 9158–9163. doi:10.1021/acscatal.9b03695. PMID 31857913. PMC 6921087. //www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=6921087. 
  16. ↑ Robinson, Marin S.; Polak, Mark L.; Bierbaum, Veronica M.; DePuy, Charles H.; Lineberger, W. C. (1995-06-01). "Experimental Studies of Allene, Methylacetylene, and the Propargyl Radical: Bond Dissociation Energies, Gas-Phase Acidities, and Ion-Molecule Chemistry". Journal of the American Chemical Society 117 (25): 6766–6778. doi:10.1021/ja00130a017. ISSN 0002-7863. https://doi.org/10.1021/ja00130a017. 
  17. ↑ Jones, E. R. H.; Mansfield, G. H.; Whiting, M. C. (1954-01-01). "Researches on acetylenic compounds. Part XLVII. The prototropic rearrangements of some acetylenic dicarboxylic acids" (en). Journal of the Chemical Society (Resumed): 3208–3212. doi:10.1039/JR9540003208. ISSN 0368-1769. https://pubs.rsc.org/en/content/articlelanding/1954/jr/jr9540003208. 
  18. ↑ "Nomenclature for cyclic organic compounds with contiguous formal double bonds (the δ-convention)". Pure Appl. Chem. 60: 1395-1401. 1988. doi:10.1351/pac198860091395. http://www.chem.qmul.ac.uk/iupac/hetero/De.html. 

Adabiyotlar

Tashqi manbalar

"https://uz.wikipedia.org/w/index.php?title=Allenlar&oldid=3302448" dan olindi