We are grateful to the Research Corporation for Science Advancement (20092), the National Science Foundation (CHE-1362140), and Texas State University for their generous support.

<ol>
	<li>Di&#769;ez-Gonza&#769;lez, S., Marion, N., Nolan, S. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=N-Heterocyclic+Carbenes+in+Late+Transition+Metal+Catalysis.">N-Heterocyclic Carbenes in Late Transition Metal Catalysis.</a> Chem. Rev. 109, 3612-3676 (2009).</li><li>Enders, D., Niemeier, O., Henseler, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Organocatalysis+by+N-Heterocyclic+Carbenes.">Organocatalysis by N-Heterocyclic Carbenes.</a> Chem. Rev. 107, 5606-5655 (2007).</li><li>Boydston, A. J., Williams, K. A., Bielawski, C. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Modular+Approach+to+Main-Chain+Organometallic+Polymers.">A Modular Approach to Main-Chain Organometallic Polymers.</a> J. Am. Chem. Soc. 127, 12496-12497 (2005).</li><li>Kamplain, J. W., Bielawski, C. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dynamic+covalent+polymers+based+upon+carbene+dimerization.">Dynamic covalent polymers based upon carbene dimerization.</a> Chem. Commun. , 1727-1729 (2006).</li><li>Back, O., Kuchenbeiser, G., Donnadieu, B., Bertrand, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Nonmetal-Mediated Fragmentation of P4: Isolation of P1and P2Bis(carbene). 48, 5530-5533 (2009).</li><li>Masuda, J. D., Schoeller, W. W., Donnadieu, B., Bertrand, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Carbene Activation of P4 and Subsequent Derivatization. 46, 7052-7055 (2007).</li><li>Masuda, J. D., Schoeller, W. W., Donnadieu, B., Bertrand, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=NHC-Mediated+Aggregation+of+P4:+Isolation+of+a+P12+Cluster..">NHC-Mediated Aggregation of P4: Isolation of a P12 Cluster..</a> J. Am. Chem. Soc. 129, 14180-14181 (2007).</li><li>Wang, Y., 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=Carbene-Stabilized+Diphosphorus.">Carbene-Stabilized Diphosphorus.</a> J. Am. Chem. Soc. 130, 14970-14971 (1021).</li><li>Wang, Y., 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=Carbene-Stabilized+Parent+Phosphinidene+Organometallics.">Carbene-Stabilized Parent Phosphinidene Organometallics.</a> 29, 4778-4780 (2010).</li><li>Back, O., Donnadieu, B., Parameswaran, P., Frenking, G., Bertrand, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation+of+crystalline+carbene-stabilized+P2-radical+cations+and+P2-dications.">Isolation of crystalline carbene-stabilized P2-radical cations and P2-dications.</a> Nature Chemistry. 2, 369-373 (2010).</li><li>Dorsey, C. L., Squires, B. M., Hudnall, T. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Isolation of a Neutral P8 Cluster by [2+2] Cycloaddition of a Diphosphene Facilitated by Carbene Activation of White Phosphorus. 52, 4462-4465 (2013).</li><li>Kuhn, K. M., Grubbs, R. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Facile+Preparation+of+Imidazolinium+Chlorides.">A Facile Preparation of Imidazolinium Chlorides.</a> Org. Lett. 10, 2075-2077 (2008).</li><li>Hudnall, T. W., Moerdyk, J. P., Bielawski, C. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ammonia+N-H+activation+by+a+N,N'-diamidocarbene.">Ammonia N-H activation by a N,N'-diamidocarbene.</a> Chem. Commun. 46, 4288-4290 (2010).</li><li>Lugan, N., Lavigne, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reprogramming+of+a+Malonic+N-Heterocyclic+Carbene:+A+Simple+Backbone+Modification+with+Dramatic+Consequences+on+the+Ligand's+Donor+Properties.">Reprogramming of a Malonic N-Heterocyclic Carbene: A Simple Backbone Modification with Dramatic Consequences on the Ligand's Donor Properties.</a> Eur. J. Inorg. Chem. 3, 361-365 (2010).</li><li>Blake, G. A., Moerdyk, J. P., Bielawski, C. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tuning+the+Electronic+Properties+of+Carbenes:+A+Systematic+Comparison+of+Neighboring+Amino+versus+Amido+Groups.">Tuning the Electronic Properties of Carbenes: A Systematic Comparison of Neighboring Amino versus Amido Groups.</a> Organometallics. 31, 3373-3378 (2012).</li><li>Martin, C. D., Weinstein, C. M., Moore, C. E., Rheingold, A. L., Bertrand, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Exploring+the+reactivity+of+white+phosphorus+with+electrophilic+carbenes:+synthesis+of+a+P4+cage+and+P8+clusters.">Exploring the reactivity of white phosphorus with electrophilic carbenes: synthesis of a P4 cage and P8 clusters.</a> Chem. Commun. 49, 4486-4488 (2013).</li></ol>

The authors have nothing to disclose.

ويرد إجراءات واضحة لتوليد carbenes زينت الكربونيل وتطبيقها في تفعيل الفسفور الأبيض هنا. الخطوات الحاسمة في البروتوكول لتوليف وcarbenes هي: (أ) التأكد من جميع المذيبات المجففة بشكل صحيح قبل استخدامها، (ب) التأكد من يتم إضافة حمض الكلوريد إلى formamidine ببطء شديد، (ج) إذا كان هو Celite ...

ظهرت carbenes مستقر كما الكواشف في كل مكان في الحفز المتجانس 1، 2 organocatalysis، وعلوم المواد 3،4، ومؤخرا الكيمياء مجموعة الرئيسي 5-9. في سياق هذا الأخير، وقد تم مؤخرا استخدام carbenes مستقر في تفعيل وfunctionalization الفوسفور الأبيض (P 4) 5-9. أصبحت القدرة على تحويل مباشرة P 4 إلى مركبات الفوسفور العضوية هدف البحث موضعي في محاولة لتطوير أساليب &quot;خضراء&quot; أن الالتفاف على استخدام السلائف الفوسفور المكلورة أو oxychlorinated. على الرغم من استخدامها على نطاق واسع، وإعداد ومناولة carbenes والمركبات المتفاعلة مثل P 4 يمكن أن يكون مهمة شاقة. لهذا السبب، فإننا قد كتبت هذه المخطوطة لتوفير بروتوكول واضح ودقيق من شأنها أن تسمح الكيميائيين الاصطناعية من جميع مستويات المهارة لتجميع والتلاعب اثنين ج مستقرة فريدة جداarbenes. بالإضافة إلى ذلك، وتفعيل P 4 باستخدام carbenes وصف مفصل. نحن هنا بالتفصيل بروتوكول لتركيب اثنين الإلكترون نقص الكربونيل carbenes زينت. لقد اخترنا هذه carbenes لأنها تختلف فقط في ممتلكاتهم بالإلكترونات، وليس المعلمات الخاصة بهم الفراغية، مما يجعلها مثالية لدراسة آثار الالكترونيات carbene على التفاعل. ويتمثل أهمية الالكترونيات carbene فيما يتعلق التفاعل من قبل اثنين من مركبات مماثلة للصيغة العامة carbene P-2 -carbene التي تم الإبلاغ عنها من قبل برتراند وروبنسون 5،8. ويدعم برتراند P 2 مشتق من قبل اثنين من دوري carbene ألكيل الأمينية (CAAC) بروابط، و هو هيكليا، photophysically، ومختلفة electrochemically من مجمع روبنسون وهو جزء P 2 تساندها طائرتان carbenes N-الحلقية غير المتجانسة (NHCs) 5،8. في الواقع، P برتراند 2 </يتميز الفرعية&gt; مجمع كمادة صلبة الأصفر الذي يتميز carbene إلى الفوسفور روابط مزدوجة في الحالة الصلبة، في حين أن مشتقات ذكرت روبنسون هو الأحمر الداكن الصلبة التي تحتوي NHC → P السندات صيغة المجرور. هذا الاختلاف الهيكلي كما يتجلى هذا electrochemically أن مجمع روبنسون يحتوي على المزيد من مراكز الفوسفور الإلكترون الغنية التي يمكن أن تخضع للعكس الأكسدة 1- أو 2 الإلكترون على النقيض من مجمع برتراند التي يمكن أن تخضع إلا الأكسدة عكسها واحدة 10. بناء على الدراسات المذكورة أعلاه، أصبحنا مهتمين في دراسة تفعيل P 4 باستخدام ثنائي الأميد وmonoamidoamino carbenes بالإلكترونات للغاية لتحديد ما إذا كان يمكن إعداد المتآصلة استقرت carbene جديدة من الفوسفور. ركزنا على diamidocarbene (DAC) 1، وcarbene monoamidoamino (MAAC) 2 التي تختلف فقط في electrophilicities كل منهم في interrogأكل ما هو الدور الذي تلعبه في الالكترونيات carbene P 4 التنشيط. ومن المثير للاهتمام عند استخدام DAC أكثر بالإلكترونات، وتريس (phosphaalkenyl) phosphane (3) يمكن أن تكون معزولة كمنتج حصري، بينما عند استخدام MAAC، واستقرت carbene P 8 متآصل (4) ويمكن الحصول على 11. نحن التحقيق أيضا آلية لتشكيل (4)، ووجدت أن يتم تشكيلها عن طريق [2 + 2] cylcoaddition dimerization رد فعل diphosphene عابرة. تم تأكيد وجود هذا diphosphene من خلال محاصرة مع 2،3-ثنائي ميثيل-1،3-بوتادين لتأثيث [4 + 2] الاضافه الحلقيه 5 معقد إضافي. يوصف بروتوكول لتوليف هذه carbenes زينت الكربونيل وعلى المقابلة P 4 مركبات تنشيط هنا.

<table border="0" cellpadding="0" cellspacing="0" width="580">
	<tbody>
		<tr height="22">
			<td height="22" style="height:22px;width:171px;">2,4,6-trimethylaniline</td>
			<td style="width:92px;">Alfa Aesar</td>
			<td style="width:123px;">AAA13049-0E</td>
			<td style="width:195px;">98%</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:171px;">Triethylorthoformate</td>
			<td style="width:92px;">Alfa Aesar</td>
			<td style="width:123px;">AAA13587</td>
			<td style="width:195px;">98%</td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:171px;">Dimethylmalonyl dichloride</td>
			<td style="width:92px;">TCI</td>
			<td style="width:123px;">D2723</td>
			<td style="width:195px;">&#62;98%</td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:171px;">3-chloro-pivaloyl chloride</td>
			<td style="width:92px;">Aldrich</td>
			<td style="width:123px;">225703-25G</td>
			<td style="width:195px;">98%</td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:171px;">Triethylamine</td>
			<td style="width:92px;">Alfa Aesar</td>
			<td style="width:123px;">AAA12646</td>
			<td style="width:195px;">Stored over dried, activated 3 &#197; molecular sieves</td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:171px;">Celite&#8482; 545</td>
			<td style="width:92px;">EMD</td>
			<td style="width:123px;">CX0574-3D</td>
			<td style="width:195px;">Oven-dried at 180 &#176;C for a minimum of 12 hrs</td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:171px;">Sodium hexamethyldisilazide</td>
			<td style="width:92px;">Across</td>
			<td style="width:123px;">200014-462</td>
			<td style="width:195px;">95+%</td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:171px;">2,3-dimethyl-1,3-butadiene</td>
			<td style="width:92px;">Alfa Aesar</td>
			<td style="width:123px;">AAAL04207-09</td>
			<td style="width:195px;">98%</td>
		</tr>
		<tr height="64">
			<td height="64" style="height:64px;width:171px;">dichloromethane</td>
			<td style="width:92px;">EMD</td>
			<td style="width:123px;">DX0835-5</td>
			<td style="width:195px;">Purified through solvent purification system, or standard methods</td>
		</tr>
		<tr height="64">
			<td height="64" style="height:64px;width:171px;">tetrahydrofuran</td>
			<td style="width:92px;">Mallinckrodt</td>
			<td style="width:123px;">8498-09</td>
			<td style="width:195px;">Purified through solvent purification system, or standard methods</td>
		</tr>
		<tr height="64">
			<td height="64" style="height:64px;width:171px;">Hexanes</td>
			<td style="width:92px;">EMD</td>
			<td style="width:123px;">HX0299-3</td>
			<td style="width:195px;">Purified through solvent purification system, or standard methods</td>
		</tr>
		<tr height="64">
			<td height="64" style="height:64px;width:171px;">Benzene</td>
			<td style="width:92px;">EMD</td>
			<td style="width:123px;">BX0220-5</td>
			<td style="width:195px;">Purified through solvent purification system, or standard methods</td>
		</tr>
		<tr height="64">
			<td height="64" style="height:64px;width:171px;">Toluene</td>
			<td style="width:92px;">BDH</td>
			<td style="width:123px;">1151-19L</td>
			<td style="width:195px;">Purified through solvent purification system, or standard methods</td>
		</tr>
		<tr height="127">
			<td height="127" style="height:127px;width:171px;">white phosphorus</td>
			<td style="width:92px;">Generously donated from the Texas A&#38;M chemistry store room.</td>
			<td style="width:123px;">NA</td>
			<td style="width:195px;">Purified through sublimation and transferred directly into a glovebox while under vacuum in the sublimator</td>
		</tr>
	</tbody>
</table>

preparation and use of carbonyl-decorated carbenes in the activation of white phosphorus

هنا نقدم بروتوكول لتركيب اثنين متميزة carbenes زينت الكربونيل. كلا carbenes يمكن إعدادها باستخدام إجراءات متطابقة تقريبا بكميات نطاق متعددة غرام. الهدف من هذا المخطوط هو بوضوح بالتفصيل كيفية التعامل مع وإعداد هذه carbenes فريد بحيث الكيميائي الاصطناعية في أي مستوى المهارات يمكن أن تعمل معهم. وcarbenes المذكورين هم diamidocarbene (DAC، carbene 1) وmonoamidoaminocarbene (MAAC 2). هذه carbenes ودرجة عالية من نقص الإلكترون وعلى هذا النحو ملامح العرض التفاعلية التي هي شاذة من أكثر carbenes N-الحلقية غير المتجانسة التقليدية. بالإضافة إلى ذلك، هذه carbenes اثنين فقط تختلف في طابعها بالإلكترونات وليس المعلمات الخاصة بهم الفراغية، مما يجعلها مثالية لدراسة كيفية تأثير carbene الالكترونيات التفاعل. لإثبات هذه الظاهرة، نحن تصف أيضا تفعيل الفوسفور الأبيض (P 4) استخدام هذه carbenes. اعتمادا على carbenالبريد المستخدمة، واثنين من المركبات المحتوية على الفوسفور مختلفة جدا يمكن أن تكون معزولة. عند استخدام DAC 1، وتريس (phosphaalkenyl) phosphane يمكن عزل كمنتج حصري. لكن اللافت للنظر، عندما MAAC 2 يضاف إلى P 4 تحت ظروف التفاعل متطابقة، يتم عزل والمدعومة carbene غير متوقع P 8 متآصل من الفوسفور حصرا. وتظهر الدراسات أن هذه الآلية المدعومة carbene P 8 أشكال متآصل عبر [2 + 2] الاضافه الحلقيه dimerization من diphosphene عابرة الذي حوصر من قبل العلاج مع 2،3-ثنائي ميثيل-1،3-بوتادين.

القدرة على عزل تريس (phosphaalkenyl) phosphane مثل 3 أو -allotrope P 8 (4) من الفسفور الأبيض تعتمد على استخدام وسيلة carbene بالإلكترونات لتفعيل P 4 رباعي الوجوه 11،16. لذا، فمن الأهمية بمكان لإعداد carbenes مع تعزيز π حموضة المعدة، وبالتالي electrophilicity الشكل 2...

Watch this Scientific Journal Video about Preparation and Use of Carbonyl-decorated Carbenes in the Activation of White Phosphorus at JoVE.com

Preparation and Use of Carbonyl-decorated Carbenes in the Activation of White Phosphorus

Here, we present a protocol for the synthesis of two carbonyl-decorated carbenes. The protocol makes these interesting compounds readily available to chemists of all skill levels. In addition to the synthesis of these two carbenes, their use in the activation of white phosphorus is also described.

إعداد واستخدام Carbenes الكربونيل زينت في تفعيل الفسفور الأبيض

Here we present a protocol for the synthesis of two distinct carbonyl-decorated carbenes. Both carbenes can be prepared using nearly identical procedures ...

preparation-use-carbonyl-decorated-carbenes-activation-white

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13.5K Views.  Texas State University. Here, we present a protocol for the synthesis of two carbonyl-decorated carbenes. The protocol makes these interesting compounds readily available to chemists of all skill levels. In addition to the synthesis of these two carbenes, their use in the activation of white phosphorus is also described.

Video: Preparation and Use of Carbonyl-decorated Carbenes in the Activation of White Phosphorus

Preparation and Use of Samarium Diiodide (SmI2) in Organic Synthesis: The Mechanistic Role of HMPA and Ni(II) Salts in the Samarium Barbier Reaction

Although initially considered an esoteric reagent, SmI2 has become a common tool for synthetic organic chemists. SmI2 is generated through the addition of molecular iodine to samarium metal in THF.1,2-3 It is a mild and selective single electron reductant and its versatility is a result of its ability to initiate a wide range of reductions including C-C bond-forming and cascade or sequential reactions. SmI2 can reduce a variety of functional groups including sulfoxides and sulfones, phosphine oxides, epoxides, alkyl and aryl halides, carbonyls, and conjugated double bonds.2-12 One of the fascinating features of SmI-2-mediated reactions is the ability to manipulate the outcome of reactions through the selective use of cosolvents or additives. In most instances, additives are essential in controlling the rate of reduction and the chemo- or stereoselectivity of reactions.13-14 Additives commonly utilized to fine tune the reactivity of SmI2 can be classified into three major groups: (1) Lewis bases (HMPA, other electron-donor ligands, chelating ethers, etc.), (2) proton sources (alcohols, water etc.), and (3) inorganic additives (Ni(acac)2, FeCl3, etc).3
Understanding the mechanism of SmI2 reactions and the role of the additives enables utilization of the full potential of the reagent in organic synthesis. The Sm-Barbier reaction is chosen to illustrate the synthetic importance and mechanistic role of two common additives: HMPA and Ni(II) in this reaction. The Sm-Barbier reaction is similar to the traditional Grignard reaction with the only difference being that the alkyl halide, carbonyl, and Sm reductant are mixed simultaneously in one pot.1,15 Examples of Sm-mediated Barbier reactions with a range of coupling partners have been reported,1,3,7,10,12 and have been utilized in key steps of the synthesis of large natural products.16,17 Previous studies on the effect of additives on SmI2 reactions have shown that HMPA enhances the reduction potential of SmI2 by coordinating to the samarium metal center, producing a more powerful,13-14,18 sterically encumbered reductant19-21 and in some cases playing an integral role in post electron-transfer steps facilitating subsequent bond-forming events.22 In the Sm-Barbier reaction, HMPA has been shown to additionally activate the alkyl halide by forming a complex in a pre-equilibrium step.23
Ni(II) salts are a catalytic additive used frequently in Sm-mediated transformations.24-27 Though critical for success, the mechanistic role of Ni(II) was not known in these reactions. Recently it has been shown that SmI2 reduces Ni(II) to Ni(0), and the reaction is then carried out through organometallic Ni(0) chemistry.28
These mechanistic studies highlight that although the same Barbier product is obtained, the use of different additives in the SmI2 reaction drastically alters the mechanistic pathway of the reaction. The protocol for running these SmI2-initiated reactions is described.

Preparation and Use of Samarium Diiodide SmI2 in Organic Synthesis: The Mechanistic Role of HMPA and NiII Salts in the Samarium Barbier Reaction

A straightforward procedure for the preparation of samarium diiodide (SmI2) in THF is described. The role of two main additives namely hexamethylphosphoramide (HMPA) and Ni(acac)2 in Sm mediated reactions is demonstrated in the Sm-Barbier reaction.

إعداد واستخدام ثنائي يوديد السمريوم (SMI<sub&gt; 2</sub&gt;) في التركيب العضوي: دور الميكنة من أملاح النيكل وHMPA (II) في رد فعل باربييه السمريوم

Although initially considered an esoteric reagent, SmI2 has become a common tool for synthetic organic chemists. SmI2 is generated through the addition of ...

The Use of Gas Chromatography to Analyze Compositional Changes of Fatty Acids in Rat Liver Tissue during Pregnancy

Gas chromatography (GC) is a highly sensitive method used to identify and quantify the fatty acid content of lipids from tissues, cells, and plasma/serum, yielding results with high accuracy and high reproducibility. In metabolic and nutrition studies GC allows assessment of changes in fatty acid concentrations following interventions or during changes in physiological state such as pregnancy. Solid phase extraction (SPE) using aminopropyl silica cartridges allows separation of the major lipid classes including triacylglycerols, different phospholipids, and cholesteryl esters (CE). GC combined with SPE was used to analyze the changes in fatty acid composition of the CE fraction in the livers of virgin and pregnant rats that had been fed various high and low fat diets. There are significant diet/pregnancy interaction effects upon the omega-3 and omega-6 fatty acid content of liver CE, indicating that pregnant females have a different response to dietary manipulation than is seen among virgin females.

Pregnancy leads to significant changes to the fatty acid composition of maternal tissues. Lipid profiles can be obtained via gas chromatography to allow identification and quantification of fatty acids in individual lipid classes among rats fed various high and low fat diets during pregnancy.

استعمال اللوني للغاز لتحليل التغييرات التركيبية من الأحماض الدهنية في الفئران الكبد الأنسجة أثناء الحمل

Gas chromatography (GC) is a highly sensitive method used to identify and quantify the fatty acid content of lipids from tissues, cells, and plasma/serum, ...

Use of Stopped-Flow Fluorescence and Labeled Nucleotides to Analyze the ATP Turnover Cycle of Kinesins

The kinesin superfamily of microtubule associated motor proteins share a characteristic motor domain which both hydrolyses ATP and binds microtubules. Kinesins display differences across the superfamily both in ATP turnover and in microtubule interaction. These differences tailor specific kinesins to various functions such as cargo transport, microtubule sliding, microtubule depolymerization and microtubule stabilization. To understand the mechanism of action of a kinesin it is important to understand how the chemical cycle of ATP turnover is coupled to the mechanical cycle of microtubule interaction. To dissect the ATP turnover cycle, one approach is to utilize fluorescently labeled nucleotides to visualize individual steps in the cycle. Determining the kinetics of each nucleotide transition in the ATP turnover cycle allows the rate-limiting step or steps for the complete cycle to be identified. For a kinesin, it is important to know the rate-limiting step, in the absence of microtubules, as this step is generally accelerated several thousand fold when the kinesin interacts with microtubules. The cycle in the absence of microtubules is then compared to that in the presence of microtubules to fully understand a kinesin&#8217;s ATP turnover cycle. The kinetics of individual nucleotide transitions are generally too fast to observe by manually mixing reactants, particularly in the presence of microtubules. A rapid mixing device, such as a stopped-flow fluorimeter, which allows kinetics to be observed on timescales of as little as a few milliseconds, can be used to monitor such transitions. Here, we describe protocols in which rapid mixing of reagents by stopped-flow is used in conjunction with fluorescently labeled nucleotides to dissect the ATP turnover cycle of a kinesin.

Kinesins are characterized by nucleotide-dependent interaction with microtubules: a cycle of ATP turnover coupled to a cycle of microtubule interaction. Here, we describe protocols to analyze the kinetics of individual nucleotide transitions in the ATP turnover cycle of a kinesin using fluorescently labeled nucleotides and stopped-flow fluorescence.

استخدام توقف تدفق الإسفار وإعتبر النيوكليوتيدات لتحليل دورة دوران اعبي التنس المحترفين من Kinesins

The kinesin superfamily of microtubule associated motor proteins share a characteristic motor domain which both hydrolyses ATP and binds microtubules. ...

HPLC Measurement of the DNA Oxidation Biomarker, 8-oxo-7,8-dihydro-2&#8217;-deoxyguanosine, in Cultured Cells and Animal Tissues

Oxidative stress is associated with many physiological and pathological processes, as well as xenobiotic metabolism, leading to the oxidation of biomacromolecules, including DNA. Therefore, efficient detection of DNA oxidation is important for a variety of research disciplines, including medicine and toxicology. A common biomarker of oxidatively damaged DNA is 8-oxo-7,8-dihydro-2&#39;-deoxyguanosine (8-oxo-dGuo; often erroneously referred to as 8-hydroxy-2&#39;-deoxyguanosine (8-OH-dGuo or 8-oxo-dG)). Several protocols for 8-oxo-dGuo measurement by high pressure liquid chromatography with electrochemical detection (HPLC-ED) have been described. However, these were mainly applied to purified DNA treated with pro-oxidants. In addition, due to methodological differences between laboratories, mainly due to differences in analytical equipment, the adoption of published methods for detection of 8-oxo-dGuo by HPLC-ED requires careful optimization by each laboratory. A comprehensive protocol, describing such an optimization process, is lacking. Here, a detailed protocol is described for the detection of 8-oxo-dGuo by HPLC-ED, in DNA from cultured cells or animal tissues. It illustrates how DNA sample preparation can be easily and rapidly optimized to minimize undesirable DNA oxidation that can occur during sample preparation. This protocol shows how to detect 8-oxo-dGuo in cultured human alveolar adenocarcinoma cells (i.e., A549 cells) treated with the oxidizing agent KBrO3, and from the spleen of mice exposed to the polycyclic aromatic hydrocarbon dibenzo(def,p)chrysene (DBC, formerly known as dibenzo(a,l)pyrene, DalP). Overall, this work illustrates how an HPLC-ED methodology can be readily optimized for the detection of 8-oxo-dGuo in biological samples.

HPLC Measurement of the DNA Oxidation Biomarker, 8-oxo-7,8-dihydro-2&amp;#8217;-deoxyguanosine, in Cultured Cells and Animal Tissues

The goal of this protocol is the detection of the DNA oxidation marker, 8-oxo-7,8-dihydro-2&#39;-deoxyguanosine (8-oxo-dGuo) by HPLC-ED, in DNA from cultured cells or animal tissues.

HPLC قياس الحمض النووي الأكسدة العلامات البيولوجية، 8 أوكسو 7،8-ثنائي هيدرو-2&#39;-deoxyguanosine، في الخلايا المستزرعة والأنسجة الحيوانية

Oxidative stress is associated with many physiological and pathological processes, as well as xenobiotic metabolism, leading to the oxidation of ...

Synthesis of Protein Bioconjugates via Cysteine-maleimide Chemistry

The chemical linking or bioconjugation of proteins to fluorescent dyes, drugs, polymers and other proteins has a broad range of applications, such as the development of antibody drug conjugates (ADCs) and nanomedicine, fluorescent microscopy and systems chemistry. For many of these applications, specificity of the bioconjugation method used is of prime concern. The Michael addition of maleimides with cysteine(s) on the target proteins is highly selective and proceeds rapidly under mild conditions, making it one of the most popular methods for protein bioconjugation.
We demonstrate here the modification of the only surface-accessible cysteine residue on yeast cytochrome c with a ruthenium(II) bisterpyridine maleimide. The protein bioconjugation is verified by gel electrophoresis and purified by aqueous-based fast protein liquid chromatography in 27% yield of isolated protein material. Structural characterization with MALDI-TOF MS and UV-Vis is then used to verify that the bioconjugation is successful. The protocol shown here is easily applicable to other cysteine - maleimide coupling of proteins to other proteins, dyes, drugs or polymers.

Synthesis of Protein Bioconjugates via Cysteine-maleimide Chemistry

This protocol details the important steps required for the bioconjugation of a cysteine containing protein to a maleimide, including reagent purification, reaction conditions, bioconjugate purification and bioconjugate characterization.

تخليق البروتين Bioconjugates<em&gt; عبر</em&gt; سيستين-maleimide الكيمياء

The chemical linking or bioconjugation of proteins to fluorescent dyes, drugs, polymers and other proteins has a broad range of applications, such as the ...

Visualization of Ambient Mass Spectrometry with the Use of Schlieren Photography

This manuscript outlines how to visualize mass spectrometry ambient ionization sources using schlieren photography. In order to properly optimize the mass spectrometer, it is necessary to characterize and understand the physical principles of the source. Most commercial ambient ionization sources utilize jets of nitrogen, helium, or atmospheric air to facilitate the ionization of the analyte. As a consequence, schlieren photography can be used to visualize the gas streams by exploiting the differences in refractive index between the streams and ambient air for visualization in real time. The basic setup requires a camera, mirror, flashlight, and razor blade. When properly configured, a real time image of the source is observed by watching its reflection. This allows for insight into the mechanism of action in the source, and pathways to its optimization can be elucidated. Light is shed on an otherwise invisible situation.

This paper presents a protocol for the visualization of gaseous streams of an ambient ionization source using schlieren photography and mass spectrometry.

تصور المحيطة الطيف الكتلي مع استخدام انعراجي التصوير الفوتوغرافي

This manuscript outlines how to visualize mass spectrometry ambient ionization sources using schlieren photography. In order to properly optimize the mass ...

Preparation and Reactivity of a Triphosphenium Bromide Salt: A Convenient and Stable Source of Phosphorus(I)

We present herein the optimized synthesis of a triphosphenium bromide salt. Apart from being a versatile metathesis reagent, this unusually stable low-valent-phosphorus-containing compound acts as a useful P+ transfer agent. Unlike traditional methods employed to access low-coordinate phosphorus species which usually require pyrophoric phosphorus-containing precursors (white phosphorus, Tris(trimethylsilyl)phosphine, etc.), or harsh reducing agents (alkali metals, potassium graphite, etc.), the current approach does not involve pyrophoric or explosive reagents and can be done on large scales (&#62;20 g) in excellent yields by undergraduates with basic air-free synthetic training. The bromide counter ion is readily exchanged with other anions such as tetraphenyl borate (described herein) using typical salt metathesis reagents to obtain materials with desired properties and reactivities. The versatility of this P+ transfer approach is exemplified by the reactions of these triphosphenium precursors with an N-heterocyclic carbene and an anionic bisphosphine, each of which readily displace the neutral bisphosphine to give an NHC-stabilized phosphorus(I) cation and a phosphorus(I) containing zwitterion, respectively.

Preparation and Reactivity of a Triphosphenium Bromide Salt: A Convenient and Stable Source of PhosphorusI

The synthesis of a triphosphenium bromide salt is described and its use as a P+ transfer agent is outlined by reactions with an N-heterocyclic carbene and an anionic bisphosphine, yielding an NHC-stabilized P(I) cation and a P(I) containing zwitterion, respectively.

إعداد والتفاعلية من Triphosphenium بروميد الملح: والمصدر مريحة ومستقرة من الفوسفور (I)

We present herein the optimized synthesis of a triphosphenium bromide salt. Apart from being a versatile metathesis reagent, this unusually stable ...

Preparation of Chitosan-based Injectable Hydrogels and Its Application in 3D Cell Culture

The protocol presents a facile, efficient, and versatile method to prepare chitosan-based hydrogels using dynamic imine chemistry. The hydrogel is prepared by mixing solutions of glycol chitosan with a synthesized benzaldehyde terminated polymer gelator, and hydrogels are efficiently obtained in several minutes at room temperature. By varying ratios between glycol chitosan, polymer gelator, and water contents, versatile hydrogels with different gelation times and stiffness are obtained. When damaged, the hydrogel can recover its appearances and modulus, due to the reversibility of the dynamic imine bonds as crosslinkages. This self-healable property enables the hydrogel to be injectable since it can be self-healed from squeezed pieces to an integral bulk hydrogel after the injection process. The hydrogel is also multi-responsive to many bio-active stimuli due to different equilibration statuses of the dynamic imine bonds. This hydrogel was confirmed as bio-compatible, and L929 mouse fibroblast cells were embedded following standard procedures and the cell proliferation was easily assessed by a 3D cell cultivation process. The hydrogel can offer an adjustable platform for different research where a physiological mimic of a 3D environment for cells is profited. Along with its multi-responsive, self-healable, and injectable properties, the hydrogels can potentially be applied as multiple carriers for drugs and cells in future bio-medical applications.

Here we describe a facile preparation of chitosan-based injectable hydrogels using dynamic imine chemistry. Methods to adjust the hydrogel&#8217;s mechanical strength and its application in 3D cell culture are presented.

إعداد المستندة إلى الشيتوزان الهلاميات المائية القابلة للحقن وتطبيقه في ثقافة الخلية 3D

The protocol presents a facile, efficient, and versatile method to prepare chitosan-based hydrogels using dynamic imine chemistry. The hydrogel is ...

The MPLEx Protocol for Multi-omic Analyses of Soil Samples

Mass spectrometry (MS)-based integrated metaproteomic, metabolomic, and lipidomic (multi-omic) studies are transforming our ability to understand and characterize microbial communities in environmental and biological systems. These measurements are even enabling enhanced analyses of complex soil microbial communities, which are the most complex microbial systems known to date. Multi-omic analyses, however, do have sample preparation challenges, since separate extractions are typically needed for each omic study, thereby greatly amplifying the preparation time and amount of sample required. To address this limitation, a 3-in-1 method for the simultaneous extraction of metabolites, proteins, and lipids (MPLEx) from the same soil sample was created by adapting a solvent-based approach. This MPLEx protocol has proven to be both simple and robust for many sample types, even when utilized for limited quantities of complex soil samples. The MPLEx method also greatly enabled the rapid multi-omic measurements needed to gain a better understanding of the members of each microbial community, while evaluating the changes taking place upon biological and environmental perturbations.

A protocol is presented for simultaneously extracting metabolites, proteins, and lipids from a single soil sample, allowing reduced sample preparation times and enabling multi-omic mass spectrometry analyses of samples with limited quantities.

بروتوكول مبليكس لمتعدد omic تحاليل عينات التربة

Mass spectrometry (MS)-based integrated metaproteomic, metabolomic, and lipidomic (multi-omic) studies are transforming our ability to understand and ...

Application of Elemental Lanthanides in the Selective C-F Activation of Trifluoromethylated Benzofulvenes Providing Access to Various Difluoroalkenes

The selective activation of one carbon-fluorine bond in polyfluorinated aromatic molecules or in trifluoromethyl-containing substrates offers the possibility of accessing unique fluorine-containing molecules, which are difficult to obtain by other synthetic pathways. Among various metals, which can undergo C-F activation, lanthanides (Ln) are good candidates as they form strong Ln-F bonds. Lanthanide metals are strong reducing agents with a redox potential Ln3+/Ln&#160;of approximately -2.3 V, which is comparable to the value of the Mg2+/Mg&#160;redox couple. In addition, lanthanide metals display a promising functional group tolerance and their reactivity can vary along the lanthanide series, making them suitable reagents for fine-tuning reaction conditions in organic and organometallic transformations. However, due to their oxophilicity, lanthanides react readily with oxygen and water and therefore require special conditions for storage, handling, preparation, and activation. These factors have limited a more widespread use in organic synthesis. We herein present how dysprosium metal - and by analogy all lanthanide metals - can be freshly prepared under anhydrous conditions using glovebox and Schlenk techniques. The freshly filed metal, in combination with aluminum chloride, initiates the selective C-F activation in trifluoromethylated benzofulvenes. The resulting reaction intermediates react with nitroalkenes to obtain a new family of difluoroalkenes.

This protocol describes the preparation of elemental lanthanides under inert atmosphere and their application in a selective C-F activation process involving trifluoromethylated benzofulvenes.