Name: controlled photoredox ring-opening polymerization of o-carboxyanhydrides mediated by ni/zn complexes
Uploaded: 2017-11-21T15:00:00.000+00:00
Duration: 5 min 48 s
Description: Watch this Scientific Journal Video about Controlled Photoredox Ring-Opening Polymerization of O-Carboxyanhydrides Mediated by Ni/Zn Complexes at JoVE.com

이 작품은 버지니아 폴 리 테크닉 연구소 및 주립 대학에서 시작 자금에 의해 지원 되었다. Q.F. 인정 국가 자연 과학 재단의 (21504047), 자연 과학 재단의 장쑤 성 (BK20150834), 게시물의 난징 대학 중국과 통신 과학 재단 NUPTSF (NY214179)에서 지원 합니다.

주의: 모든 관련 재료 안전 데이터 시트 (MSDS) 사용 하기 전에 참조 하십시오. 많은 화학 물질 합성에 사용 되는 심하게 독성 발암 성입니다. 반응 공학 컨트롤 (증기 두건 및 글러브) 및 개인 보호 장비 (안전 안경, 장갑, 실험실 외 투, 전장 바지, 폐쇄 발가락 신발, 블루 빛의 사용을 포함 하 여 수행할 때 모든 적절 한 안전 관행을 사용 하시기 바랍니다 안전 차단 고글). 다음 절차는 장갑 상자에 표준 공기 무료 처리 기술을 포함. 모든 솔루션 피 펫을 사용 하 여 전송 됩니다.
1입니다. 촉매 및 초기자의 준비
참고: 전체 프로세스는 콜드 트랩으로 글러브 박스에서 실시. 모든 화학 물질 건조 또는 상자에 이동 하기 전에 정화. 13 모든 병 및 유리는 건조 하 고 상자에 이동 하기 전에 오븐에서가 열.
<ol><li>
(Bpy)Ni(COD) 솔루션의 준비 참고: (bpy)Ni(COD) 갓 대비해 야 제자리에. 그것은 장갑 상자 냉동 실 (-35 ° C)에 저장 한다 고 1 주일 이내 사용. 모든 다른 촉매 및 초기자 솔루션 수 있습니다 저장할 수 글러브 박스 냉장고에 1 개월 이상.<ol>
<li>7 mL 섬광 유리병에 Ni(COD)2 (3.5 mg, 12.7 µmol, 1.0 eq)를 무게.</li>
		<li>2, 2 '-bipyridine (5.9 mg, 37.8 µmol) 섬광 7 mL 유리병에 무게.</li>
		<li>2, 2-bipyridine 무수 tetrahydrofuran (THF)의 1 mL에 용 해.</li>
		<li>결과 2, 2 ' bipyridine 솔루션 (337 µ L) Ni(COD)2를 들어 있는 유리병에 추가 합니다.</li>
		<li>무수 THF의 1 mL에 섞어 희석.</li>
		<li>유리병 뚜껑을 2 시간에 대 한 실 온에서 반응 혼합물을 두십시오. 참고: Ni(COD)2 , THF에 용 해 되지 않습니다 반면 (bpy)Ni(COD)는 THF에 용 해. 2 시간 후에 보라색 솔루션에 강 수 있어야 합니다.</li>
		<li>저장소 (bpy)Ni(COD)-35 ° C 냉동 고에.</li>
	</ol>
</li>
	<li>
Zn(HMDS)2 솔루션의 준비
	<ol>
<li>7 mL 섬광 유리병에 Zn(HMDS)2 (3.3 mg, 4 µ L, 8.5 µmol)를 추가 합니다.</li>
		<li>Zn(HMDS)2 무수 THF의 1 mL에 용 해.</li>
		<li>-35 ° C 냉동 고에서 Zn(HMDS)2 솔루션을 저장 합니다.</li>
	</ol>
</li>
	<li>
BnOH 솔루션의 준비
	<ol>
<li>7 mL 섬광 유리병에 BnOH (4.0 mg, 4 µ L, 37.0 µmol)를 추가 합니다.</li>
		<li>BnOH 무수 THF의 4 mL에 용 해.</li>
		<li>-35 ° C 냉동 고에서 BnOH 솔루션을 저장 합니다.</li>
	</ol>
</li>
	<li>
Ir-1 솔루션의 준비
	<ol>
<li>글로브 박스 빛을 해제 합니다. 주의: 그것은 중 합 전에 Ir-1 의 비활성화를 방지 하려면 글로브 박스 빛 해제 해야 합니다.</li>
		<li>7 mL 섬광 유리병에 Ir-1 (2.9 mg, 2.6 µmol)를 추가 합니다.</li>
		<li>Ir-1 무수 THF의 3 mL에 용 해.</li>
		<li>-35 ° C 냉장고에서 Ir-1 솔루션을 저장 합니다.</li>
	</ol>
</li>
</ol>2. l-1의 Photoredox 반지 개통 중 합
참고: 전체 프로세스는 콜드 트랩으로 글러브 박스에서 실시. 모든 OCA 단위체는 박막 사용 하기 전에 장갑 상자에. 13 여기 우리에 게는 중 합 예 DP에서 = 500 ([l -1] /[(bpy)Ni(COD)]/[Zn(HMDS)2] / [BnOH] / [Ir-1] = 500/1/1/1/0.1). 다른 DPs에 중합체는 단위체를 대량 적절 하 게 조정 하 여 준비 또한 수 있습니다.
<ol><li>
중 합을 위한 l-1 솔루션의 준비
	<ol>
<li>7 mL 섬광 유리병에 l-1 (72.2 mg, 375.7 µmol)를 추가 합니다.</li>
		<li>무수 THF의 722 µ L에서 l-1 를 분해.</li>
		<li>다른 7 mL 섬광 유리병 볶음 바 장착으로 l-1 솔루션의 200 µ L를 추가 합니다.</li>
		<li>7 mL 섬광 유리병에 무수 THF의 100 µ L를 추가 합니다.</li>
		<li>유리병 뚜껑과 콜드 트랩에 l-1 솔루션을 놓습니다.</li>
		<li>글로브 박스 빛을 해제 합니다. 주의: 그것은 중 합 전에 Ir-1 의 비활성화를 방지 하려면 글로브 박스 빛 해제 해야 합니다.</li>
	</ol>
</li>
	<li>
콜드 트랩 냉각
	<ol>
<li>박스 안에 콜드 트랩에 온도계를 넣어.</li>
		<li>상자, ca. 에탄올 500ml에 추가 dewar 플라스 크.</li>
		<li>Dewar 플라스 크에 액체 질소를 추가 합니다.</li>
		<li>콜드 트랩에 KGW dewar 플라스 크를 로드 합니다.</li>
		<li>쿨-50 ° c.에 콜드 트랩</li>
		<li>놔 파문 접시 아래 추위 트랩 ( 그림 1참조).</li>
	</ol>
</li>
	<li>
Photoredox 반지 개통 중 합을 수행 참고: 시작 하기 전에 중 합, 장소 안전 고글 블록 블루 빛 도달 시간. 모든 촉매 시스템 솔루션은 즉시 냉동 실에서 촬영 하 고 있는 일시 중지 또는 중단 없이 동작 하는 l-1 의 20 밀리 그램 이상 30 7 mL 섬광 유리병으로 연속적으로 추가 s.<ol>
<li>추가 (bpy)Ni(COD) 솔루션 (16.4 µ L, 0.208 µmol) l-1 (2.1에서 준비)를 포함 하는 7 mL 섬광 유리병에.</li>
		<li>유리병에 Zn(HMDS)2 솔루션 (24.4 µ L, 0.208 µmol)를 추가 합니다.</li>
		<li>유리병에 BnOH 솔루션 (22.5 µ L, 0.208 µmol)를 추가 합니다.</li>
		<li>유리병에 Ir-1 솔루션 (24.2 µ L, 0.0208 µmol)를 추가 하 고 유리병 뚜껑.</li>
		<li>블루 LED 빛을 차단 하는 안전 고글을 착용. 주의: 파란색 LED로 상대 강도 높은 조명 사용, 전체 과정에서 안전 고글을 착용.</li>
		<li>라이트 블루 LED 빛 (34 승)에 LED에 의해 생성 된 열을 방산 하 팬 설정. 콜드 트랩에 유리병으로 빛을 직접. (그림 1)</li>
		<li>교 반기를 켭니다.</li>
		<li>커버 알루미늄 호 일로 콜드 트랩.</li>
		<li>-15 ± 5 ° C에서 반응 온도 유지 하 고 추가 액체 질소 15 ~ 20 분 간격. 참고: 반응 온도 유지 중 합 및 MW 제어에 대 한 중요 하다.</li>
	</ol>
</li>
</ol>3. 모니터 퓨 리에 변환 적외선 스펙트럼에 의해 단위체 변환
참고: 퓨 리에 변환 적외선 스펙트럼 (FTIR) 다이아몬드 ATR 및 전송 샘플링 액세서리를 갖춘 FT-적외선 분석기에 기록 됩니다.
<ol><li>특정 시간 점에서 7 mL 섬광 유리병에 폴리머 솔루션 (20 µ L)의 작은 약 수를 추가 하 고 출장.</li>
	<li>글러브 박스에서 유리병을 제거 합니다.</li>
	<li>즉시 솔루션 (3 µ L) ATR FTIR 다이아몬드 샘플러에 드롭. 10 필름을 형성 하는 솔루션 스펙트럼 측정에 대 한 s.</li>
	<li>샘플의 FTIR 스펙트럼을 측정 합니다. 참고: 단위체 변환 1760 c m-1 와 1805s c m-1간 강도 비율에 의해 결정 되었다: 변환 % = 내가1760/ (나1760 +1805) (대표 결과 그림2에서). 일반적으로 중 합 걸립니다 약 1-8 h 200에서 1000 까지의 DP (자세한 활동 참조 13에서 설명).</li>
</ol>4. 젤 투과 크로마토그래피에 의해 고분자의 분자량의 측정
참고: 겔 침투 크로마토그래피 (GPC) 실험 degasser, multiangle 레이저 산란 (MALS) 검출기와 isocratic 펌프를 갖춘 시스템에서 수행 됩니다 (GaAs 30 mW 레이저 λ = 690 nm), 및 차동 굴절률 (DRI) 검출기 와 함께 690 nm 빛 소스. 분판을 직렬 연결된 크기 제외 열을 사용 하 여 수행 됩니다 (100 Å, 500 Å, 103 Å, 그리고 10 Å4 열, 5 µ m, 300 × 4.6 m m) THF를 사용 하 여 a 0.35 mL/min의 유량에서 모바일 위상으로 35 ° C에서. 고분자 분자량 (MW) 및 분자량 분포 (Ð) MALS DRI 데이터의 맞는 Zimm 모델을 사용 하 여 결정 됩니다. 금속 고분자에 복잡 한의 존재는 GPC 측정 결과 영향을 미치지 않습니다.
<ol><li>글러브 박스에서 폴리머 솔루션 (50 µ L)의 작은 약 수를 제거 합니다.</li>
	<li>유리병에 THF의 100 µ L를 추가 합니다.</li>
	<li>GPC 샘플러에 샘플을 삽입할.</li>
	<li>GPC 실행 완료 되 면 결과 분석 합니다. 참고: 폴리머 좁은 Đ 와 monodispersed 이어야 한다 (대표 결과 그림3에서). 폴리머 (20mg) 건조 하 고 1 mL diethyl 에테르 Ni의 87% 및 Zn 단지, 유도 결합된 플라즈마 질량 분석 (ICP-MS)에 의해 결정의 50%를 제거할 수 있습니다 1% 메탄올 HOAc 및 1 mL를 포함 하 여 씻어 수 있습니다.</li>
</ol>

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Chem. 52, 2306-2315 (2014).</li><li>Buchard, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Preparation+of+stereoregular+isotactic+poly(mandelic+acid)+through+organocatalytic+ring-opening+polymerization+of+a+cyclic+O-carboxyanhydride.">Preparation of stereoregular isotactic poly(mandelic acid) through organocatalytic ring-opening polymerization of a cyclic O-carboxyanhydride.</a> Angew. Chem. Int. Ed. 53, 13858-13861 (2014).</li><li>Zhuang, X. -. l., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Polymerization+of+lactic+O-carboxylic+anhydride+using+organometallic+catalysts.">Polymerization of lactic O-carboxylic anhydride using organometallic catalysts.</a> Chin. J. Polym. Sci. 29, 197-202 (2010).</li><li>He, Z., Jiang, L., Chuan, Y., Li, H., Yuan, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ring-opening+polymerization+of+L-lactic+acid+O-carboxyanhydrides+initiated+by+alkoxy+rare+earth+compounds.">Ring-opening polymerization of L-lactic acid O-carboxyanhydrides initiated by alkoxy rare earth compounds.</a> Molecules. 18, 12768-12776 (2013).</li><li>Jia, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=One-pot+atom-efficient+synthesis+of+bio-renewable+polyesters+and+cyclic+carbonates+through+tandem+catalysis.">One-pot atom-efficient synthesis of bio-renewable polyesters and cyclic carbonates through tandem catalysis.</a> Chem. Commun. 51, 8504-8507 (2015).</li><li>Tong, R., Cheng, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Drug-initiated,+controlled+ring-opening+polymerization+for+the+synthesis+of+polymer-drug+conjugates.">Drug-initiated, controlled ring-opening polymerization for the synthesis of polymer-drug conjugates.</a> Macromolecules. 45, 2225-2232 (2012).</li><li>Bonduelle, C., Martin-Vaca, B., Bourissou, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lipase-catalyzed+ring-opening+polymerization+of+the+O-carboxylic+anhydride+derived+from+lactic+acid.">Lipase-catalyzed ring-opening polymerization of the O-carboxylic anhydride derived from lactic acid.</a> Biomacromolecules. 10, 3069-3073 (2009).</li><li>Yamamoto, T., Igarashi, K., Komiya, S., Yamamoto, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Preparation+and+properties+of+phosphine+complexes+of+nickel-containing+cyclic+amides+and+esters+[(PR3)nNiCH2CH(R1)COZ+(Z+=+NR2,+O)].">Preparation and properties of phosphine complexes of nickel-containing cyclic amides and esters [(PR3)nNiCH2CH(R1)COZ (Z = NR2, O)].</a> J. Am. Chem. Soc. 102, 7448-7456 (1980).</li><li>Deming, T. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Amino+acid+derived+nickelacycles:+intermediates+in+nickel-mediated+polypeptide+synthesis.">Amino acid derived nickelacycles: intermediates in nickel-mediated polypeptide synthesis.</a> J. Am. Chem. Soc. 120, 4240-4241 (1998).</li><li>Lee, D. -. Y., Hartwig, J. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Zinc+trimethylsilylamide+as+a+mild+ammonia+equivalent+and+base+for+the+amination+of+aryl+halides+and+triflates.">Zinc trimethylsilylamide as a mild ammonia equivalent and base for the amination of aryl halides and triflates.</a> Org. Lett. 7, 1169-1172 (2005).</li><li>Yin, Q., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Drug-initiated+ring-opening+polymerization+of+O-carboxyanhydrides+for+the+preparation+of+anticancer+drug-poly(O-carboxyanhydride)+nanoconjugates.">Drug-initiated ring-opening polymerization of O-carboxyanhydrides for the preparation of anticancer drug-poly(O-carboxyanhydride) nanoconjugates.</a> Biomacromolecules. 14, 920-929 (2013).</li></ol>

저자 아무 경쟁 금융 관심사를 선언합니다. 임시 특허 (미국 특허 응용 프로그램 번호: 62/414,016)이이 문서에 소개 된 결과 관련 된 제기 되었습니다.

프로토콜 내에서 중요 한 단계-15 ±에서 반응 온도 유지 하는 5 ° c. 모든 촉매 솔루션 및 OCA 단위체는 중 합 하기 전에-35 ° C에서 글러브 박스 냉장고에 저장할 수 있다. 반응 튜브 미리 콜드 트랩에 냉각 해야 합니다. 반응, 동안 LED 빛, 열 방출 되므로 반응 15-20 분 마다 모니터링 하는 데 필요한. 일단 온도 발생을-10 ° C에 액체 질소 추가 해야 함정을 dewar에. 낮은 온도 대 한 이유는 실내 온도 제어 p...

폴 리 (α-hydroxy 산) (PAHA)는 생 분해성 및 생체 고분자 생물 의학 장치에서 포장 재료에 이르기까지 응용 프로그램의 중요 한 클래스. 1 , 2 비록 PAHAs는 직접 α-hydroxy 산의 축 중 합에 의해 준비 될 수 있다, 결과 PAHAs의 분자 무게 (MWs)는 일반적으로 낮은. 3 반지 개통 중 합 (ROP) lactones (예: lactide 및 glycolide)의 축 중 합 보다 MWs와 분자량 분포 (Đ)에 더 나은 제어를 제공 하는 다른 합성 접근 이다. 그러나, 사이드 체인 기능 PAHAs와 lactones의 부족 육체 및 화학 재산 및 그들의 응용의 다양성을 제한 합니다. 4 , 5 2006 년부터, 1, 3-dioxolane-2, 4-디, 소위 O-carboxyanhydrides (졸업), 다양 한 사이드 체인 기능,6,,78, 준비 될 수 있는 9 , 10 , 11 , 12 , 13 폴 리 에스테 르 중 합에 대 한 높은 활성 단위체의 대체 클래스 등장 했습니다. 14 , 15
졸업의 ROP에 대 한 촉매 시스템 organocatalysts,8,12,,1617 유기 금속 촉매12,18,19 로 분류 될 수 있다 20,21 그리고 biocatalysts. 22 epimerization (즉, stereoregularity의 부족) 졸업 전자 철회 그룹,8,17 베어링 등 다소 통제 방식으로 일반적으로, 졸업의 ROP organocatalyst에 의해 추진 진행 예측할 수 없는 MWs, 또는 느린 중 합 속도 론입니다. 13 이러한 문제를 해결 하려면 활성 Zn alkoxide 복잡 한 졸업 ROP에 대 한 개발 되었다. 12 well-controlled Rop epimerization 없이 합 (DP)의 낮은 정도에 달성 했다. 그러나,이 Zn alkoxide 촉매는 고분자 중 합 (DP ≥ 300)의 높은 수준의 생산 효율적으로 수 없습니다. 13
우리 최근 사용자와 PAHA 합성 (그림 1)의 효율은 크게 향상 유망한 접근을 보고 있다. 13 우리는 OCA decarboxylation 아연 alkoxide 반지 개통 중 합 졸업의 중재와 홍보 photoredox Ni/Ir 촉매를 병합 합니다. 낮은 온도 (-15 ° C) 및 photoredox Ni/Ir 촉매의 사용은 반지-체인 전파, 바람직하지 않은 측면 반응을 피하고 있는 동안 예를 들어, Ni 카보닐기의 형성에 대 한 OCA의 decarboxylation와 synergistically 가속 한다. 23 , 24 transmetalation Ni 복잡 한와 따라 활성 Zn alkoxide는 체인 전파에 대 한 체인에 있습니다. 13
이 프로토콜에 신선한 준비 추가 (bpy)Ni(COD) (bpy = 2, 2'-bipyridyl, 대구 = 1, 5-cyclooctadiene), Zn(HMDS)2 (HMDS = hexamethyldisilazane),25 벤 질 알코올 (BnOH)와 Ir [dF (CF3) ppy]2(dtbbpy) PF6 ( Ir-1, dF (CF3) ppy = 2-(2, 4-difluorophenyl)-5-(trifluoromethyl) pyridine, dtbbpy = 4, 4'-디-tert-부 틸-2, 2'-bipyridine)에 모노 머 l-1 솔루션26 의 존재에서 콜드 트랩으로 글러브 박스에는 블루 LED 빛 (400-500 nm)과 온도 (그림 1)를 유지 하기 위해 팬. 온도-15 ° C ± 5 ° C에는 중 합 동안 유지 됩니다. OCA의 변환 푸리에 변환 적외선 분광학에 의해 모니터링 됩니다. 결과 폴리머 MWs Đ의젤 투과 크로마토그래피 (GPC)에 의해 특징입니다. Homodecoupling 1H NMR 연구 획득된 폴리머 아이 소 택 틱 인지 여부를 결정 합니다. 대부분의 화학 물질은 습기에 매우 민감한, 자세한 비디오 프로토콜 새로운 실무자 photoredox ROP의 졸업과 관련 된 함정을 피할 수 있도록 위한 것입니다.

<table><tbody><tr><td>Ni(COD)&lt;sub&gt;2&lt;/sub&gt;</td><td>Strem</td><td>28-0010</td><td>Stored in the glove box freezer.</td></tr><tr><td>2,2&amp;prime;-bipyridine</td><td>Strem</td><td>07-0290</td><td>Stored in the glove box freezer.</td></tr><tr><td>Zn(HMDS)&lt;sub&gt;2&lt;/sub&gt;</td><td>N/A</td><td>N/A</td><td>Synthesized following reported procedures.&lt;sup class=&quot;xref&quot;&gt;25&lt;/sup&gt; Stored in the glove box freezer.</td></tr><tr><td>Benzyl alcohol</td><td>Sigma-Aldrich</td><td>402834</td><td>Stored with 4&amp;Aring; molecular sieve</td></tr><tr><td>Ir[dF(CF&lt;sub&gt;3&lt;/sub&gt;)ppy]&lt;sub&gt;2&lt;/sub&gt;(dtbbpy)PF&lt;sub&gt;6&lt;/sub&gt;</td><td>Strem</td><td>77-0425</td><td>Stored in the glove box freezer.</td></tr><tr><td>THF</td><td>Sigma-Aldrich</td><td>34865</td><td>Dried by alumina columns and stored with 4&amp;Aring; molecular sieve in the dark bottle in the glove box.</td></tr><tr><td>Ethanol</td><td>Sigma-Aldrich</td><td>793175</td><td></td></tr><tr><td>GPC with an isocratic pump</td><td>Agilent</td><td>Agilent 1260 series</td><td></td></tr><tr><td>Dawn Heleos II Light Scatterer</td><td>Wyatt</td><td></td><td></td></tr><tr><td>Optilab rEX differential refractive index detector</td><td>Wyatt</td><td></td><td></td></tr><tr><td>Size exclusion columns</td><td>Phenomenex</td><td></td><td></td></tr><tr><td>Glass Scintillation Vials - 7 ml</td><td>VWR</td><td></td><td></td></tr><tr><td>FTIR spectrometer</td><td>Agilent</td><td></td><td></td></tr><tr><td>Stir bars</td><td>VWR</td><td>58948-091</td><td></td></tr><tr><td>Balance</td><td></td><td></td><td></td></tr><tr><td>Glove box</td><td>Mbraun</td><td>Labstar Pro</td><td></td></tr></tbody></table>

controlled photoredox ring-opening polymerization of o-carboxyanhydrides mediated by ni/zn complexes

여기, 우리가 예상된 분자 무게와 효율적인 반지 개통 중 합, 아이 소 택 틱 폴 리 (α-hydroxy 산)의 합성에 대 한 허용에 대 한 Zn alkoxide를 사용 하 여 photoredox Ni/Ir 촉매를 결합 하는 효과적인 프로토콜을 설명 (> 140 kDa) 좁은 분자량 분포 (Mw/Mn < 1.1). 이 반지 개통 중 합은 Ni와 Zn 단지 알코올 초기자와 파란색 LED (400-500 nm)에 의해 조사 photoredox Ir 촉매의 존재에 의해 중재 됩니다. 중 합을 피하기 위해 바람직하지 않은 측면 반응 낮은 온도 (-15 ° C)에서 수행 됩니다. 좁은 분자량 분포와 가까운 예상된 분자량 폴리머를 제공 4-8 시간 전체 단위체 소비를 얻을 수 있습니다. 결과 수 평균 분자량 1000까지 합의 학위를 가진 선형 상관 관계를 보여 줍니다. Homodecoupling 1H NMR 연구 획득된 폴리머 epimerization 없이 아이 소 택 틱 확인 합니다. 이 중 합 본 보고 준비 stereoregular 폴 리 (α-hydroxy 산)와 다양 한 기능적 측면 체인 그룹 베어링의 공중 합체를 신속 하 고 제어 O-carboxyanhydrides 중 합을 달성 하기 위한 전략을 제공 합니다.

그림 2와 같이 OCA의 변환 푸리에 변환 적외선 분광학에 의해 모니터링 됩니다. 1805 c m-1 에서 피크 무수 물 본드 스트레치 OCA;에 할당 하는 1760 c m-1 에서 피크는 폴리머에 에스테 르 결합의 형성에 해당합니다. 단위체의 피크 1805 c m-1 에서 완전히 사라지면, 일단은 중 합 완료 됩니다.
<p class="jove_content" fo:keep-together.within-page="...

Watch this Scientific Journal Video about Controlled Photoredox Ring-Opening Polymerization of O-Carboxyanhydrides Mediated by Ni/Zn Complexes at JoVE.com

Controlled Photoredox Ring-Opening Polymerization of O-Carboxyanhydrides Mediated by Ni/Zn Complexes

O-carboxyanhydrides Ni/Zn 단지 중재의 제어 photoredox 반지 개통 중 합에 대 한 프로토콜 제공 됩니다.

O-Carboxyanhydrides Ni/Zn 단지 중재의 Photoredox 반지 개통 중 합 제어

Here, we describe an effective protocol that combines photoredox Ni/Ir catalysis with the use of a Zn-alkoxide for efficient ring-opening polymerization, ...

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Controlled Photoredox Ring-Opening Polymerization of O-Carboxyanhydrides Mediated by Ni/Zn Complexes

8.0K 조회수.  Nanjing University of Posts and Telecommunications. O-carboxyanhydrides Ni/Zn 단지 중재의 제어 photoredox 반지 개통 중 합에 대 한 프로토콜 제공 됩니다.

비디오: Controlled Photoredox Ring-Opening Polymerization of O-Carboxyanhydrides Mediated by Ni/Zn Complexes

Ethylene Polymerizations Using Parallel Pressure Reactors and a Kinetic Analysis of Chain Transfer Polymerization

We demonstrate a method for high-throughput catalyst screening using a parallel pressure reactor starting from the initial synthesis of a nickel &#945;-diimine ethylene polymerization catalyst. Initial polymerizations with the catalyst lead to optimized reaction conditions, including catalyst concentration, ethylene pressure and reaction time. Using gas-uptake data for these reactions, a procedure to calculate the initial rate of propagation (kp) is presented. Using the optimized conditions, the ability of the nickel &#945;-diimine polymerization catalyst to undergo chain transfer with diethylzinc (ZnEt2) during ethylene polymerization was investigated. A procedure to assess the ability of the catalyst to undergo chain transfer (from molecular weight and 13C NMR data), calculate the degree of chain transfer, and calculate chain transfer rates (ke) is presented.

A protocol for the high-throughput analysis of polymerization catalyst, chain transfer polymerizations, polyethylene characterization, and reaction kinetic analysis is presented.

병렬 반응기 압력 및 연쇄 이동 중합 키네틱 분석을 사용하여 에틸렌 중합

We demonstrate a method for high-throughput catalyst screening using a parallel pressure reactor starting from the initial synthesis of a nickel ...

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화학

Atom Transfer Radical Polymerization of Functionalized Vinyl Monomers Using Perylene as a Visible Light Photocatalyst

A standardized technique for atom transfer radical polymerization of vinyl monomers using perylene as a visible-light photocatalyst is presented. The procedure is performed under an inert atmosphere using air- and water-exclusion techniques. The outcome of the polymerization is affected by the ratios of monomer, initiator, and catalyst used as well as the reaction concentration, solvent, and nature of the light source. Temporal control over the polymerization can be exercised by turning the visible light source off and on. Low dispersities of the resultant polymers as well as the ability to chain-extend to form block copolymers suggest control over the polymerization, while chain end-group analysis provides evidence supporting an atom-transfer radical polymerization mechanism.

A method for the atom transfer radical polymerization of functionalized vinyl monomers using perylene as a visible-light photocatalyst is described.

가시광 광촉매 페 릴렌 사용 관능 비닐 모노머의 원자 이동 라디칼 중합

A standardized technique for atom transfer radical polymerization of vinyl monomers using perylene as a visible-light photocatalyst is presented. The ...

Solid-phase Synthesis of [4.4] Spirocyclic Oximes

A convenient synthetic route for spirocyclic heterocycles is well sought after due to the molecule&#39;s potential use in biological systems. By means of solid-phase synthesis, regenerating Michael (REM) linker strategies, and 1,3-dipolar cycloaddition, a library of structurally similar heterocycles, both with and without a spirocyclic center, can be constructed. The main advantages of the solid-support synthesis are as follows: first, each reaction step can be driven to completion using a large excess of reagents resulting in high yields; next, the use of commercially available starting materials and reagents keep the costs low; finally, the reaction steps are easy to purify via simple filtration. The REM linker strategy is attractive because of its recyclability and traceless nature. Once a reaction scheme is completed, the linker can be reused multiple times. In a typical solid-phase synthesis, the product contains either a part of or the whole linker, which can prove undesirable. The REM linker is &#34;traceless&#34; and the point of attachment between the product and the polymer is indistinguishable. The high diastereoselectivity of the intramolecular 1,3-dipolar cycloaddition is well documented. Limited by the insolubility of the solid support, the reaction progression can only be monitored by a change in the functional groups (if any) via infrared (IR) spectroscopy. Thus, the structural identification of intermediates cannot be characterized by conventional nuclear magnetic resonance (NMR) spectroscopy. Other limitations to this method stem from the compatibilities of the polymer/linker to the desired chemical reaction scheme. Herein we report a protocol that allows for the convenient production of spirocyclic heterocycles that, with simple modifications, can be automated with high-throughput techniques.

Here we present a protocol to demonstrate an efficient method for the synthesis of spirocyclic heterocycles. The five-step process utilizes solid-phase synthesis and regenerating Michael linker strategies. Generally difficult to synthesize, we present a customizable method for the synthesis of spirocyclic molecules otherwise inaccessible to other modern approaches.

[4.4] Spirocyclic Oximes의 고체 상 합성

A convenient synthetic route for spirocyclic heterocycles is well sought after due to the molecule&#39;s potential use in biological systems. By means of ...

Photogeneration of N-Heterocyclic Carbenes: Application in Photoinduced Ring-Opening Metathesis Polymerization

We report a method to generate the N-heterocyclic carbene (NHC) 1,3-dimesitylimidazol-2-ylidene (IMes) under UV-irradiation at 365 nm to characterize IMes and determine the corresponding photochemical mechanism. Then, we describe a protocol to perform ring-opening metathesis polymerization (ROMP) in solution and in miniemulsion using this NHC-photogenerating system. To photogenerate IMes, a system comprising 2-isopropylthioxanthone (ITX) as the sensitizer and 1,3-dimesitylimidazolium tetraphenylborate (IMesH+BPh4-) as the protected form of NHC is employed. IMesH+BPh4- can be obtained in a single step by anion exchange between 1,3-dimesitylimidazolium chloride and sodium tetraphenylborate. A real-time steady-state photolysis setup is described, which hints that the photochemical reaction proceeds in two consecutive steps: 1) ITX triplet is photo-reduced by the borate anion and 2) subsequent proton transfer takes place from the imidazolium cation to produce the expected NHC IMes. Two separate characterization protocols are implemented. Firstly, CS2 is added to the reaction media to evidence the photogeneration of NHC through formation of the IMes-CS2 adduct. Secondly, the amount of NHC released in situ is quantified using acid-base titration. The use of this NHC photo-generating system for the ROMP of norbornene is also discussed. In solution, a photopolymerization experiment is conducted by mixing ITX, IMesH+BPh4-, [RuCl2(p-cymene)]2 and norbornene in CH2Cl2, then irradiating the solution in a UV reactor. In a dispersed medium, a monomer miniemulsion is first formed then irradiated inside an annular reactor to produce a stable poly(norbornene) latex.

We describe a protocol to photogenerate N-heterocyclic carbenes (NHCs) by UV irradiation of a 2-isopropylthioxanthone/imidazolium tetraphenylborate salt system. Methods to characterize the photoreleased NHC and elucidate the photochemical mechanism are proposed. The protocols for ring-opening metathesis photopolymerization in solution and miniemulsion illustrate the potential of this 2-component NHC photogenerating system.

N-이종 환 식 Carbenes의 Photogeneration: Photoinduced 반지 개통 Metathesis 중 합에 응용

We report a method to generate the N-heterocyclic carbene (NHC) 1,3-dimesitylimidazol-2-ylidene (IMes) under UV-irradiation at 365 nm to characterize IMes ...

[(DPEPhos)(bcp)Cu]PF6: A General and Broadly Applicable Copper-Based Photoredox Catalyst

Our group recently reported the use of [(DPEPhos)(bcp)Cu]PF6 as a general copper-based photoredox catalyst which proved efficient to promote the activation of a broad variety of organic halides, including unactivated ones. These can then participate in various radical transformations such as reduction and cyclization reactions, as well as in the direct arylation of several (hetero)arenes. These transformations provide a straightforward access to a range of small molecules of interest in synthetic chemistry, as well as to biologically active natural products. Altogether, [(DPEPhos)(bcp)Cu]PF6 acts as a convenient photoredox catalyst which appears to be an attractive, cheap and complementary alternative to the state-of-the-art iridium- and ruthenium-based photoredox catalysts. Here, we report a detailed protocol for the synthesis of [(DPEPhos)(bcp)Cu]PF6, as well as NMR and spectroscopic characterizations, and we illustrate its use in synthetic chemistry for the direct arylation of (hetero)arenes and radical cyclization of organic halides. In particular, the direct arylation of N-methylpyrrole with 4-iodobenzonitrile to afford&#160;4-(1-methyl-1H-pyrrol-2-yl)benzonitrile and the radical cyclization of N-benzoyl-N-[(2-iodoquinolin-3-yl)methyl]cyanamide to afford natural product luotonin A are detailed. The scope and limitations of this copper-based photoredox catalyst are also briefly discussed.

[DPEPhosbcpCu]PF6: A General and Broadly Applicable Copper-Based Photoredox Catalyst

Detailed and general protocols are presented for the synthesis of [(DPEPhos)(bcp)Cu]PF6, a general copper-based photoredox catalyst, and for its use in synthetic chemistry for the direct arylation of C-H bonds in (hetero)arenes and radical cyclization of organic halides.

[(Bcp)] PF6: 일반적이 고 광범위 하 게 적용 가능한 구리 기반 포토에도 x 촉매

Our group recently reported the use of [(DPEPhos)(bcp)Cu]PF6 as a general copper-based photoredox catalyst which proved efficient to promote the ...

Cercosporin-Photocatalyzed [4+1]- and [4+2]-Annulations of Azoalkenes Under Mild Conditions

The interest on nitrogen-containing heterocycles has expanded rapidly in the synthetic community since they are important motifs for new drugs. Traditionally, they were synthesized through thermal cycloaddition reactions, whereas today, photocatalysis is preferred due to the mild and efficient conditions. With this focus, a new photocatalytic method for the synthesis of nitrogen-containing heterocycles is highly desired. Here, we report a protocol for the biosynthesis of cercosporin, which could function as a metal-free photocatalyst. We then illustrate cercosporin-photocatalyzed protocols for the synthesis of nitrogen-containing heterocycles 1,2,3-thiadiazoles through annulation of azoalkenes with KSCN, and synthesis of 1,4,5,6-tetrahydropyridazines [4+2] through cyclodimerization of azoalkenes under mild conditions, respectively. As a result, there is a new bridge between the microbial fermentation method and organic synthesis in a mild, cost-effective, environmentally friendly and sustainable manner.

New routes for the synthesis of nitrogen-containing heterocycles utilizing cercosporin as a metal-free photocatalyst were developed.

세르코스포린-포토카탈루즈 [4+1]- 및 [4+2]-온화한 조건하에서 아졸케네스의 탄화

The interest on nitrogen-containing heterocycles has expanded rapidly in the synthetic community since they are important motifs for new drugs. ...

Depolymerizable Olefinic Polymers Based on Fused-Ring Cyclooctene Monomers

The growing consumption of synthetic polymers and the accumulation of polymer waste have led to a pressing need for new routes to sustainable materials. Achieving a closed-loop polymer economy via chemical recycling to monomer (CRM) is one such promising route. Our group recently reported a new CRM system based on polymers prepared by ring-opening metathesis polymerization (ROMP) of trans-cyclobutane fused cyclooctene (tCBCO) monomers. This system offers several key advantages, including the ease of polymerization at ambient temperatures, quantitative depolymerization to monomers under mild conditions, and a broad range of functionalities and thermomechanical properties. Here, we outline detailed protocols for the preparation of tCBCO-based monomers and their corresponding polymers, including the preparation of elastic polymer networks and compression molding of linear thermoplastic polymers. We also outline the preparation of high ring strain E-alkene tCBCO monomers and their living polymerization. Finally, the procedures for the depolymerization of linear polymers and polymer networks are also demonstrated.

Here, we describe protocols for the preparation of trans-cyclobutane fused cyclooctenes (tCBCO),&#160;their polymerization to prepare depolymerizable olefinic polymers, and the depolymerization of these polymers under mild conditions. Additionally, protocols for the preparation of depolymerizable networks and compression molding of rigid linear plastics based on this system are described.

융합 고리 사이클로옥텐 단량체를 기반으로 하는 해중합 가능한 올레핀 폴리머

The growing consumption of synthetic polymers and the accumulation of polymer waste have led to a pressing need for new routes to sustainable materials. ...

Photochemical Initiation Of Radical Polymerization Reactions

Source: David C. Powers, Tamara M. Powers, Texas A&#38;M
In this video, we will carry out the photochemically initiated polymerization of styrene to generate polystyrene, which is an important commodity plastic. We will learn the fundamentals of photochemistry and use simple photochemistry to initiate radical polymerization reactions. Specifically, in this module we will examine the photochemistry of benzoyl peroxide and its role as a photo-initiator of styrene polymerization reactions. In the described experiments, we will investigate the role of wavelength, photon absorption, and excited state structure on the efficiency (measured as quantum yield) of photochemical reactions.

급진적 중합 반응의 광화학 개시

Source: David C. Powers, Tamara M. Powers, Texas A&#38;M
In this video, we will carry out the photochemically initiated polymerization of styrene to ...

교육

JoVE Science Education

무기 화학

Acid-Catalyzed Ring-Opening of Epoxides

Epoxides that are three-membered ring systems are more reactive than other cyclic and acyclic ethers. The high reactivity of epoxides originates from the strain present in the ring. This ring strain acts as a driving force for epoxides to undergo ring-opening reactions either with halogen acids or weak nucleophiles in the presence of mild acid. The acid catalyst converts the epoxide oxygen, a poor leaving group, into an oxonium ion, a better leaving group, making the reaction feasible. The reaction follows the SN2 mechanism, and the protonated oxygen, unlike other leaving groups, does not detach from the molecule. The regiochemistry of the products formed is governed by either steric or electronic effects. In the case of an asymmetrical epoxide bearing a primary and a secondary carbon, the steric effect dominates and favors the nucleophilic attack at a less-hindered carbon. However, in epoxides where one of the carbons is tertiary, the electronic effect comes into play and favors the attack at a more-hindered carbon. The stereochemistry of the products is similar to an SN2 reaction, where the nucleophile attacks anti to the leaving group. Notably, the anti-attack at a chiral carbon causes an inversion of configuration.

에폭사이드의 산 촉매 고리 개구부

Epoxides that are three-membered ring systems are more reactive than other cyclic and acyclic ethers. The high reactivity of epoxides originates from the ...

JoVE Core

유기화학

Unit 1

Ethers, Epoxides, Sulfides

주요 용어 및 개념

Base-Catalyzed Ring-Opening of Epoxides

Due to their highly strained structures, epoxides can readily undergo ring-opening reactions through nucleophilic substitution, either in the presence of an acid or a base. The nucleophilic substitution reactions in the presence of acid are called acid-catalyzed ring-opening reactions, and nucleophilic substitution reactions in the presence of a base are called base-catalyzed ring-opening reactions. Epoxides undergo base-catalyzed ring-opening reactions in the presence of a strong nucleophile or a base. A variety of nucleophiles like sodium hydroxide, sodium alkoxide, sodium hydrosulfide, sodium cyanide, lithium aluminum hydride, and Grignard reagent can open the epoxide ring. The nucleophilic attack on the epoxide ring proceeds via an SN2 mechanism and involves an alkoxide intermediate. The product formed in base-catalyzed reactions shows SN2-like stereoselectivity and regioselectivity. The nucleophile attacks at the less-hindered carbon and anti to the leaving group, leading to the inversion of configuration at a chiral center. In contrast to epoxides, acyclic ethers do not undergo direct nucleophilic substitutions, as the reaction is thermodynamically unfavorable.

에폭사이드의 염기 촉매 고리 개구부

Due to their highly strained structures, epoxides can readily undergo ring-opening reactions through nucleophilic substitution, either in the presence of ...