Name: air-free solvent transfer by vacuum
Uploaded: 2023-04-30T06:30:46.000Z
Duration: 9 min 41 s
Channel: JoVE

K12 Standards

new-york-state-science-learning-standards

New York State Science Learning Standards

High School

Physical Science

HS. Chemical Reactions

HS-PS1-2.

Schlenk Lines Transfer of Solvents

1. 使用施伦克线
1&#160;启动
<ol>
	<li>确保 manifold 上所有工作端口均已关闭，并且所有接口均均匀涂抹了高真空润滑脂。</li>
	<li>将溶剂捕集阱连接至真空管线，并开启真空泵进行密封。注意：每台真空泵在系统抽气时都会发出“独特”的声音。熟悉您的真空泵在抽气过程中以及达到完全真空时的正常声音非常重要。</li>
	<li>在溶剂捕集阱周围放置真空密封杜瓦瓶，并向杜瓦瓶中加入液氮（最佳）或干冰/丙酮浆（仅适用于低蒸气压溶剂——存在损坏真空泵的风险），以低温保护真空泵。</li>
	<li>打开受控的惰性气体气流，通过观察鼓泡器的冒泡速率调节气体流量。（每 10 秒约 5 个气泡的流速较为理想）</li>
	<li>使用厚壁橡胶管或直接使用标准磨口玻璃仪器，将所需装置连接至 manifold 的端口。</li>
	<li>通过执行 3 次抽真空/惰性气体回填循环，清除反应头空间（以及可能的装置内部）残留的空气和水分：（1）将反应端口打开至真空，等待达到完全真空后，关闭反应端口与真空的连接；（2）缓慢地将反应端口通入惰性气体，等待鼓泡器重新开始冒泡。若迅速打开惰性气体端口，可能导致空气通过鼓泡器被吸入系统。随后关闭反应端口与惰性气体的连接；（3）总共重复 3 次。</li>
</ol>
2 关闭
<ol>
	<li>关闭所有多通阀的端口，并关闭惰性气体气流。</li>
	<li>取下溶剂捕集阱的杜瓦瓶。注意：若在取下时发现捕集阱中存在蓝色液体，则可能是液氧（沸点 -183 °C），其可在液氮温度（沸点 -196 °C）下冷凝，并与有机化合物形成爆炸性混合物，或在系统升温时因快速增压而在密闭系统中引发爆炸。7 若发现液氧存在，应立即重新装回杜瓦瓶以保持捕集阱低温，关闭通风橱窗，通知周围人员。保持捕集阱连接且系统处于真空状态，让其缓慢升温并蒸发。为避免冷凝液氧，应确保多通阀系统无泄漏，并尽量减少系统在真空下暴露于空气中的时间。液氩（沸点 -186 °C）也可能发生类似情况，应注意避免将大量氩气抽入液氮（LN2）捕集阱中。</li>
	<li>关闭真空泵，并通过打开溶剂捕集阱的放空阀（如配备）或主真空多通阀上的端口，将系统通入环境大气中。</li>
	<li>拆下溶剂捕集阱，并将其中捕集的挥发性物质倒入适当的废液容器中处理。</li>
</ol>
2. 烃类溶剂/试剂的干燥
警告： 金属钠与水发生剧烈反应。Ketyl 自由基与某些溶剂存在严重不相容性，特别是卤代溶剂。在为特定溶剂选择合适的干燥剂之前，应查阅适当的参考文献。请遵循《实验室化学品纯化》中的相关指南。8-9
1 “溶剂锅”的制备——每升溶剂加入 5 g Ph2CO。10
<ol>
	<li>参见图1以获取所需玻璃器皿。在惰性气氛下，称取约1 cm5,6金属钠（丝状或块状），将其切割成较小碎片，并放入带有24/40标准磨口颈的500-mL圆底烧瓶中。</li>
	<li>称取约1.25 g二苯甲酮（Ph2CO），并将其与钠一同加入500&#160;mL圆底烧瓶中。</li>
	<li>将一个高强度搅拌子放入500&#160;mL圆底烧瓶中，然后使用已涂抹少量高强度高真空润滑脂的180° 24/40接头密封烧瓶。在接头处安装Keck夹具，以确保连接牢固。</li>
	<li>将烧瓶从手套箱中取出，并按照第1.2.6节所述方法在施伦克线或高真空线上进行抽气。在保持真空状态下，密封180°接头，并将烧瓶从真空线上取下。</li>
	<li>将漏斗连接至溶剂锅顶部（切勿使用润滑脂！），并在漏斗中加入所需溶剂。使用连接氮气管线的长针，向溶剂中通入氮气以进行初步脱气。</li>
	<li>在持续通氮气的同时，缓慢打开180°接头，使溶剂流入溶剂锅中。当漏斗内液面接近180°接头时，关闭接头并移除漏斗。&#160;注意：溶剂可通过其他方式加入，其无水无氧操作的严格程度有所不同。通常，用户可选择在开放空气中加料，随后进一步脱气；也可选择直接从溶剂纯化系统中取用预先干燥的溶剂进行填充。</li>
	<li>搅拌溶剂锅数小时，期间溶液将变为深紫色，表明钠-二苯甲酮联苯甲醇自由基已生成。若溶液未变为深紫色，则对溶液进行脱气处理（见第2.2节），并再次搅拌。</li>
</ol>
2 通过冻抽-解冻循环去除溶剂中的气体
警告： 液氮常用于在冻抽-解冻循环中“冷冻”溶剂。除非绝对必要并在咨询主管人员后，强烈建议不要使用液氮。将密闭系统冷却至液氮温度会显著增加系统泄漏时液化氧气的风险。此外，较大的温度梯度会因热冲击而增加玻璃器皿破裂的可能性。在几乎所有情况下，将系统冷却至 -78 °C 即可充分满足脱气需求，同时将溶剂损失降至最低。
<ol style="margin-left: 40px;">
	<li>启动Schlenk线或高真空系统（第1.1节），并将溶剂瓶连接至多通管（第1.1.6节）。</li>
	<li>使用干冰/丙酮冷却浴将瓶内溶剂冷却至-78 °C。根据溶剂的凝固点，这可能导致溶剂冻结。&#160; 注意：“冷冻-抽气-解冻”过程中一个常见的误解是必须将溶剂完全冻结才能脱气。这是不正确的；事实上，冷液体比冻结的固体更容易脱气，因为气体容易被困在固体基质中。</li>
	<li>如果溶剂的凝固点高于-78 °C且已冻结，打开180°接头使溶剂瓶与真空相连，以除去瓶内顶部空间的气体。&#160; 等待系统恢复至完全真空后，关闭溶剂瓶与真空的连接。</li>
	<li>让溶剂瓶恢复至室温，并观察固/液混合物中是否有气泡产生。若有气泡出现，则表明溶剂尚未完全脱气，应重复步骤2.2.2–2.2.4。通常进行三次“冷冻-抽气-解冻”循环即可充分脱气。</li>
	<li>如果溶剂的凝固点低于-78 °C，且在-78 °C时具有较低的蒸气压，则可不执行步骤2.2.3和2.2.4，而直接将溶剂瓶与真空连接约5分钟（或直至气泡停止产生），以实现系统脱气。5分钟后关闭180°接头。少量溶剂可能被带入真空泵捕集阱中。</li>
	<li>如果溶剂的凝固点低于-78 °C，且在-78 °C时具有较高的蒸气压，则有两种选择：采用液氮代替-78 °C冷却浴进行步骤2.2.3和2.2.4（溶剂损失较少，但风险较高），或缩短步骤2.2.5的操作时间（溶剂损失较多，但更安全）。</li>
</ol>
3. 真空转移溶剂/化学品
<ol>
	<li>将一个500 mL的接收用Straus烧瓶和一个U形真空转移桥在干燥烘箱（125 °C）中干燥至少1小时。</li>
	<li>将Straus烧瓶和溶剂瓶连接到U形桥上，并在所有接口处均匀涂抹少量真空润滑脂。将U形桥连接至真空管线。&#160; 注意： 该系统较重，应使用升降架和Keck夹具进行支撑，以防止其从管线上脱落并破裂。仅靠真空歧管的吸力可能不足以稳固地固定该系统。</li>
	<li>按照步骤1.1.6所述方法对系统抽真空。</li>
	<li>按照第2.2节所述方法对溶剂瓶进行脱气。</li>
	<li>关闭U形桥顶部的阀门，使真空转移装置与动态真空隔离。此时系统应处于静态真空状态，Straus烧瓶的阀门保持打开，而溶剂瓶的180°适配器保持关闭。</li>
	<li>使用升降架将装有-78 °C丙酮/干冰的冷却浴升至接收用Straus烧瓶周围，以冷却该烧瓶。&#160; 警告： 禁止使用液氮冷却密闭系统，因为一旦系统存在泄漏，极有可能冷凝出液氧，造成严重安全隐患。尽管在液氮温度下进行真空转移可能速度更快，但其安全风险远大于收益。本操作在我方实验室中被明令禁止。若某种溶剂无法在-78 °C条件下完成真空转移，建议采用更高真空度或考虑采用热蒸馏方法。</li>
	<li>开启磁力搅拌器以搅拌溶剂瓶，然后缓慢打开溶剂瓶上180°适配器的活塞，防止溶剂瓶中的液体迅速暴沸进入U形接头。</li>
	<li>不久后，溶剂应开始在接收烧瓶中冷凝。等待直至溶剂瓶几乎完全干燥或已收集到所需量的溶剂。随后关闭接收用Straus烧瓶的活塞及溶剂瓶上的阀门，溶剂瓶可重新加料或再次使用。</li>
	<li>若在转移过程中溶剂瓶发生冻结，应先关闭Straus烧瓶的阀门，待溶剂瓶自然升温至室温后再继续操作。</li>
	<li>若真空转移过程极慢或明显变慢，应按照第2.2节中的规程重新对系统进行脱气处理。</li>
</ol>
4. 在氮气手套箱中测试收集的溶剂
1 酮基溶液的制备
<ol>
	<li>在20&#160;mL小瓶中称取0.137 g Ph2CO和超过0.028 g的钠金属。</li>
	<li>向小瓶中加入20 mL THF和一根小搅拌子，盖上瓶盖后搅拌过夜。应得到浓度为0.0337 M的深紫色Na/Ph2CO羰基自由基溶液，瓶底残留少量过量的钠。&#160;</li>
</ol>
2 收集溶剂的滴定
<ol>
	<li>将约 4 mL 待测溶剂移入一个 4&#160;mL 小瓶</li>
	<li>使用巴斯德吸管小心地滴加 单个 紫色 Na/Ph 滴液2将CO THF溶液加入小瓶中。</li>
	<li>轻轻用移液管搅拌小瓶中的溶液 清洁 移液枪头并分析产生的颜色。含有10 ppm H的溶剂2O级或更低级别应保持淡紫色。非蓝色</li>
	<li>如果溶剂会与 Ph 发生反应2CO自由基（例如 卤代溶剂（如二氯甲烷）、通过卡尔·费休滴定法检测溶剂，或对于氘代溶剂， 1,2,3氢核磁共振波谱法&#160;</li>
</ol>

施伦克线溶剂转移

来源：Hsin-Chun Chiu 和 Tyler J. Morin，Ian Tonks 博士实验室——明尼苏达大学双城分校
施伦克线（Schlenk lines）和高真空线均通过在惰性气体（通常为 N2 或 Ar）的微正压或真空条件下进行反应，以排除反应中的水分和氧气。真空转移技术被开发用于将溶剂（或其他挥发性试剂）从干燥剂（或其他非挥发性试剂）中分离，并将其转移至反应或储存容器中，同时维持无空气的环境。与热蒸馏类似，真空转移通过在另一个接收容器中蒸发并冷凝溶剂来实现分离；然而，真空转移利用施伦克线和高真空线歧管中的低压，使溶剂的沸点降低至室温甚至更低，从而实现低温蒸馏。该技术可为收集无水无氧溶剂提供一种比热蒸馏更安全的替代方法。在真空转移完成后，可通过卡尔·费休滴定法对所收集溶剂中的水分含量进行定量测定，也可通过钠/二苯基萘（Na/Ph2CO）溶液滴定进行定性检测，或通过 1H 核磁共振（NMR）波谱法进行分析。

正在拍摄真空转移过程中的图片（图2）以及钠/苯基反应后2CO 滴定滴定实验已执行（图3).
通过该方法收集的溶剂已通过酮醇滴定法进行检测。 图3 显示了酮醇试验的常见可能结果。(a) 中的紫色表明 &lt; 10 ppm H2溶剂中的蓝色和无色溶液表明溶剂含水量较高，需在用于对水敏感的应用前进一步纯化。
<img alt="蒸馏装置用玻璃器皿组件；包括用于实验室的烧瓶、接头和连接件。" src="/files/ftp_upload/5679/5679fig1.jpg" data-altupdatedat="1761830439000" data-alt="图1"> 
图1. 制备ketyl反应瓶及向Straus烧瓶进行减压转移所需的玻璃器皿。 (a) 向ketyl反应瓶...

来源：Hsin-Chun Chiu 和 Tyler J. Morin，Ian Tonks 博士实验室——明尼苏达大学双城分校  
Schlenk 线和高真空线是……

某些化学反应必须保持无水无氧。Schlenk 线是一种双排管装置，用于安全操作对空气和水分敏感的试剂。该装置由 Wilhelm Schlenk 于 20 世纪 20 年代发明。其设计中的一个关键部件是 Schlenk 烧瓶。它带有旋塞，可根据需要向系统施加真空或惰性气体。瓶口可与其他装置连接，或用隔垫密封，从而可在不引入空气的情况下加入试剂。一旦将试剂加入装置后，即可在无氧无水的环境中对其进行操作。本视频将重点介绍施伦克线的基本操作步骤，然后通过溶剂的真空转移实验在实验室中演示其原理。Schlenk 线是一种管状玻璃装置，其中一条管线用于提供真空，另一条管线用于输送惰性气体。这两条管线共同构成一个双排管系统。双排管具有四到六个带阀门的接口，通过厚橡胶管连接至各种反应装置。惰性气体排管连接至经过压力调节的惰性气体源，并通过油鼓泡器排气，以使管线压力略高于大气压。油鼓泡器还可防止环境空气进入排管，从而避免管线污染。将真空多通管连接至真空泵。在真空多通管与泵之间需安装一个低温捕集阱，通常使用液氮或干冰-溶剂混合物进行冷却，用于冷凝挥发性组分，防止其进入并损坏真空泵。施伦克线系统可用于多种技术和反应，例如溶剂的真空转移。该过程涉及在保持无空气环境的同时，将溶剂从一个容器转移至另一个容器。现在您已经了解了施伦克线操作的原理，接下来我们演示如何转移无空气和无氧溶剂。首先，确保 manifold 上所有工作端口均处于关闭状态，并且所有接口均已均匀涂抹高真空润滑脂。将溶剂捕集器连接到真空管线上，并通过开启真空泵进行密封。将真空密封的杜瓦瓶放置在溶剂捕集器周围，并用液氮填充，以对泵进行低温保护。打开可控惰性气体气流，通过观察鼓泡器调节流量。使用厚壁橡胶管或标准磨口玻璃仪器，将所需装置（如施伦克瓶）连接到多通管的接口上。通过首先将反应口连接至真空，完全抽空烧瓶中的顶空来清除烧瓶内的气体。关闭与真空的连接，然后缓慢打开反应口通入惰性气体，并等待鼓泡器重新开始冒泡。关闭惰性气体通路，再重复此过程两次。下一步是准备一个溶剂蒸馏装置。该装置用于制备敏感反应所需的无水无氧溶剂。本实验采用常见的二苯甲酮-钠体系。 首先，将玻璃器皿和试剂放入惰性气氛的手套箱中。取约一立方厘米的钠金属，并将其切割成较小的碎片。将碎片放入带有标准磨口颈接头的500 mL圆底烧瓶中。称取1.25 g二苯甲酮，并将其加入含有钠的圆底烧瓶中。加入一个高强度搅拌子。使用少量重型高真空润滑脂润滑180° 24/40接头后，将其密封在烧瓶上。在接口处放置一个Keck夹，以确保连接牢固。将烧瓶从手套箱中取出，并使用施伦克线抽空烧瓶顶部空间。密封180°接头，并在保持真空条件下将烧瓶从管线上取下。将漏斗连接至溶剂瓶顶部，向漏斗中加入约 300 mL 所需溶剂。将连接氮气管线的长针插入溶剂中，通入氮气鼓泡，使溶剂部分脱气。在持续通入氮气的同时，缓慢打开180°适配器，将溶剂引入溶剂瓶中。当漏斗中的液面接近适配器时，关闭适配器并取下漏斗。搅拌数小时。溶液将变为深紫色，表明生成了钠-二苯甲酮自由基（sodium benzophenone ketyl radical）。自由基的形成表明溶剂已干燥且无氧。如果溶液未变为深紫色，则需对溶液进行脱气处理。采用冷冻-抽气-解冻法，具体操作详见本合集中的“通过冷冻-抽气-解冻循环对液体进行脱气”。将一个500 mL的接收斯特劳斯烧瓶和一个U形真空转移桥在干燥箱中干燥。斯特劳斯烧瓶是一种双颈圆底烧瓶，其中一个颈部带有螺纹，可用于连接插塞阀。在所有接头处均匀涂抹少量真空脂，将U形桥连接至真空管线。将Straus烧瓶和溶剂瓶连接到U形桥上。务必使用Keck夹固定该较重的装置系统。抽真空并按照前述方法对溶剂进行脱气处理。关闭顶部U型桥阀以切断真空。系统应在Straus阀打开且溶剂瓶180°适配器关闭的情况下保持静态真空。使用实验室升降架将-78°C的丙酮/干冰浆液升至接收用Straus烧瓶处，以进行冷却。开始搅拌溶剂瓶，然后缓慢打开180°接头的活塞。务必缓慢旋转活塞，以防止液体迅速沸腾进入U型接头。溶剂将开始在接收瓶中冷凝。若在转移过程中溶剂瓶冻结，请关闭Straus瓶阀门，待溶剂瓶升温至室温后再继续操作。如果溶剂转移极其缓慢，使用冷冻-抽气-解冻法再次对系统进行脱气。等待溶剂瓶几乎蒸干，或收集到所需量的溶剂。关闭接收瓶和溶剂瓶上的活塞。此时可将密封的烧瓶从系统中取下。关闭系统时，首先关闭所有歧管端口，并关闭惰性气体流量。接下来，移除溶剂捕集器和杜瓦瓶。如果捕集器中存在任何蓝色液体，必须格外小心，因其可能是液态氧。请参照安全规程采取适当措施。施伦克线系统广泛应用于有机化学中多种对空气敏感的反应。量子点被广泛用于单分子荧光成像。在此示例中，量子点在惰性气氛下使用施伦克线（Schlenk line）合成。首先在惰性气体和真空条件下合成小尺寸的硒化镉量子点核。其荧光特性由纳米粒子的尺寸决定。将硒迅速注入镉溶液中，以完成核的合成。随后，通过修饰汞和生物相容性聚合物涂层，提高其荧光产率。这些量子点的荧光持续时间远超过传统染料或蛋白质。挥发性及对空气敏感气体的处理与分析通常具有挑战性，但使用施伦克线（Schlenk line）可安全地完成。在此示例中，利用施伦克线将挥发性气体转移至可密封的试管中。使用液氮冷却试管，以冷凝气体并将其捕获在试管中。然后利用密封的试管和定制的连接系统，将所含气体转移至质谱仪中。您刚刚观看了 JoVE 关于施伦克线系统的介绍。现在您应该了解如何操作施伦克线、干燥和纯化溶剂，以及如何进行真空转移。感谢观看！

Education

教育

JoVE Science Education

Chemistry

化学

Organic Chemistry

有机化学

溅镀转移的溶剂

air-free solvent transfer by vacuum

Schlenk lines and high vacuum lines are used to move solvents without exposing them to moisture or oxygen. They do this by keeping reactions under a slight overpressure of inert gas, usually nitrogen or argon, or by using vacuum.

Vacuum transfer is a separate method for isolating solvents and other volatile reagents from drying agents or other nonvolatile materials. It lets users dispense clean solvent into a reaction vessel or storage vessel while the air-free environment is maintained. The method works in a way that is similar to thermal distillation, because the solvent is vaporized and then condensed in a second receiving vessel.

A key advantage of vacuum transfer is that the low pressure in Schlenk and high vacuum line manifolds lowers boiling points to room temperature or even below. This makes cryogenic distillations possible. It can also be a safer alternative to thermal distillation when collecting air-free, moisture-free solvents.

After transfer, the collected solvent can be checked for water content. Common tests include Karl Fischer titration, titration with a Na/Ph2CO solution, and 1H NMR spectroscopy.

Air-Free Solvent Transfer by Vacuum

introduction to catalysis

Catalysis in Industry and Sustainability

Catalysis is a major part of modern technology. It helps chemical reactions happen by lowering activation energy, which is the energy needed to start a reaction. Catalysts can also affect selectivity, or which products form during a reaction. Catalysis has a large impact on industry and daily life. It is linked to about 35% of global GDP. It also supports the food supply for about 33% of the world’s population through fertilizers made by the Haber process. Because catalysts improve how...

assembly of a reflux system for heated chemical reactions

assembly-of-a-reflux-system-for-heated-chemical-reactions

Reflux Setup for Heating Reactants Safely

A reflux setup lets chemists heat reactants without losing material to evaporation. Many chemical experiments need elevated temperatures before a reaction starts. When the reactants or solvent have low boiling points, heating can cause them to escape as vapor. A reflux system prevents that loss by condensing the vapor that forms during heating. The condensed liquid then flows back into the reaction vessel. This keeps the reactants and solvent in the flask while the reaction is heated.

conducting reactions below room temperature

conducting-reactions-below-room-temperature

Cooling Baths for Low-Temperature Reactions

Low-temperature reactions are often run with cooling baths to keep the reaction flask below room temperature. Chemists use this setup when they want a reaction to stay within a specific temperature range. The reagents in the flask do not touch the cooling bath itself. Reaction rate depends on molecular collisions. At higher temperatures, atoms and molecules move faster, collide more often, and react more effectively. A common rule of thumb based on the Arrhenius equation says that raising the...

schlenk lines transfer of solvents

Schlenk lines and high vacuum lines are used to move solvents without exposing them to moisture or oxygen. They do this by keeping reactions under a slight overpressure of inert gas, usually nitrogen or argon, or by using vacuum. Vacuum transfer is a separate method for isolating solvents and other volatile reagents from drying agents or other nonvolatile materials. It lets users dispense clean solvent into a reaction vessel or storage vessel while the air-free environment is maintained. The...

degassing liquids with freeze-pump-thaw cycling

degassing-liquids-with-freeze-pump-thaw-cycling

Freeze-Pump-Thaw for Removing Dissolved Gases

Freeze-pump-thaw cycling is a method for removing dissolved gases from a liquid. Degassing means taking dissolved gases out of a liquid. These gases can include oxygen or carbon dioxide. Dissolved gases can cause problems in the lab. They can interfere with chemical reactions that use sensitive reagents. They can also affect spectroscopic measurements and cause unwanted bubble formation. Several methods can be used to degas liquids. These include heating, ultrasonic agitation, chemical...

preparing anhydrous reagents and equipment

preparing-anhydrous-reagents-and-equipment

Moisture-Free Setup for Organic Reactions

Many organic reactions must be set up without water. Moisture in the air can react with sensitive reagents before the reaction even starts. When that happens, the desired reaction may fail or give poor yields because the reactants have changed chemically. To prevent this, the reaction is run under an inert atmosphere. An inert atmosphere is a gas environment that does not react easily with the chemicals in the flask. Nitrogen gas is often used, and argon may be used for reactions that are even...

purifying compounds by recrystallization

Recrystallization for Solid Compound Purity

Recrystallization is a technique for purifying solid compounds. It uses the fact that solids are often more soluble in hot liquids than in cold liquids. An impure solid is dissolved in a hot liquid until the solution becomes saturated, meaning it holds as much dissolved material as it can at that temperature. The solution is then allowed to cool. As the temperature drops, the compound should form relatively pure crystals. Most impurities should stay in the solution and not become part of the...

separation of mixtures via precipitation

Solubility-Based Mixture Separation

Solubility-based separation removes a compound from a mixture by making it insoluble in water. Most samples of interest contain many different components, so sample preparation is an important step before analysis. It helps remove interferences that could affect the results. This separation method is useful in both academic and industrial settings. The process relies on the solubility properties of compounds in aqueous solutions. A compound’s solubility can depend on ionic strength, pH, and...

solid-liquid extraction

Solvent Separation in Solid Samples

Solid samples can be prepared for chemical analysis by moving the target analyte into a liquid. This solid-liquid extraction step is used in many chemical analyses before spectroscopic or chromatographic identification and quantification. It helps separate the analyte from the rest of the sample matrix, which is the material surrounding it. A simple approach is to mix the solid with a solvent that can dissolve the analyte. Agitation helps the analyte leave the solid and partition into the...

rotary evaporation to remove solvent

Rotovap Use in Organic Chemistry

Rotary evaporation is a common lab method for drying and purifying samples in organic chemistry. It helps remove a solvent from a compound of interest when the compound has a higher boiling point. A rotary evaporator is often called a rotovap. The rotovap was invented in 1950 by the chemist Lyman C. Craig. It is widely used because it works quickly and can handle large volumes of solvent. For this reason, many laboratories prefer rotary evaporation when they need to remove low boiling point...

fractional distillation

Separating Liquids by Boiling Point

Fractional distillation separates liquid mixtures by using differences in boiling point. Chemists use this lab technique to purify organic liquids. When a mixture is carefully distilled, compounds with different boiling points split into individual parts. There are two main types of distillation: simple distillation and fractional distillation. Simple distillation is used when a liquid is relatively pure, when it contains no more than 10% liquid contaminants, or when it has a non-volatile...

growing crystals for x-ray diffraction analysis

growing-crystals-for-x-ray-diffraction-analysis

X-ray Crystal Growth for Structure Analysis

X-ray crystal growth is a key step in X-ray crystallography, the method used to determine the spatial arrangement of atoms in a crystalline solid. That structure reveals the three-dimensional shape of a molecule or complex. Since structure and function are closely linked, this information can help explain a compound's behavior and reactivity. X-ray crystallography is one of the most useful ways to solve a compound's three-dimensional structure. In some cases, it may be the only practical...

performing 1d thin layer chromatography

Thin Layer Chromatography for Mixture Separation

Thin layer chromatography separates mixtures of non-volatile compounds. It uses a TLC plate with a thin layer of adsorbent material as the stationary phase. The adsorbent layer is fixed to a solid support such as plastic, aluminum, or glass. The sample and a reference compound are first dissolved in a suitable solvent. They are then applied as small spots near the bottom edge of the TLC plate. This placement helps the compounds move with the developing solvent in a controlled way. To run the...

column chromatography

Purifying Compounds with a Chromatography Column

Column chromatography is a useful method for purifying compounds. It uses a stationary phase packed into a column and a mobile phase that flows through it. The separation works because different molecules have different polarities, so they move through the column at different rates. The most common stationary phases are silica gel, or SiO2, and alumina, or Al2O3. The mobile phase is usually an organic solvent. The solvent choice depends on the polarity of the molecules being purified. More...

nuclear magnetic resonance (nmr) spectroscopy

nuclear-magnetic-resonance-nmr-spectroscopy

Using NMR to Track Organic Reactions

Nuclear magnetic resonance (NMR) spectroscopy helps organic chemists study molecules and check reaction results. It can show molecular structure, sample content, and sample purity. Because NMR is non-destructive, it is useful when the sample needs to be recovered after analysis. One of the most common methods is proton, or 1H, NMR. Protons in a molecule respond differently depending on their chemical environment. That difference makes it possible to infer the structure of the molecule from the...

organic chemistry

该系列的特点是在有机化学实验室中经常使用的技术, 侧重于在化学反应和 post-reaction 细化过程中调节温度和气氛。

Learn how Schlenk lines and high vacuum lines move solvents under inert gas or vacuum, separate them from drying agents, and support air-free collection.

Air-Free Solvent Transfer by Vacuum | JoVE K12

HS-PS1-5.

Overview

Principles of Schlenk Line Transfer

Schlenk Line Startup

Preparation of a Solvent Pot

Vacuum Transfer of Solvents

Applications

Summary

The Periodic Table

As early chemists discovered more elements, they realized that various elements could be grouped by their similar chemical behaviors. One such grouping ...

Alkali Metals

Group 1 elements are soft and shiny metallic solids. They are malleable, ductile, and good conductors of heat and electricity. The melting points of the ...

Halogens

Group 17 elements, known as halogens, are nonmetals. At room temperature, fluorine and chlorine are gases, bromine is a liquid, and iodine a solid. ...

Noble Gases


The elements in group 18 are noble gases (helium, neon, argon, krypton, xenon, and radon). They earned the name &ldquo;noble&rdquo; because they were ...

Classifying Matter by State

Chemistry is the study of matter and the changes it undergoes. Matter is anything that has mass and occupies space. Matter is all around us; the air, ...

Classifying Matter by Composition

Matter: Pure Substances and Mixtures
According to its composition, the matter can be classified into two broad categories &mdash; pure substances and ...

physical-and-chemical-properties-of-matter

Physical and Chemical Properties of Matter

The characteristics that enable us to distinguish one substance from another are called properties.

Physical Properties of Matter

A physical property is ...

Types of Chemical Bonds

Chemical bonding theories were pioneered by American chemist Gilbert&#xA0;N. Lewis. He developed a model called the Lewis model to explain the type and ...

Lewis Symbols and the Octet Rule

Chemical bonds are complex interactions between two or more atoms or ions, which reduce the potential energy of the molecule. Gilbert N. Lewis developed a ...

Ionic Bonding and Electron Transfer

Ions are atoms or molecules bearing an electrical charge. A cation (a positive ion) forms when a neutral atom loses one or more electrons from its valence ...

The Born-Haber Cycle

Lattice Energy&#xA0;

An ionic compound is stable because of the electrostatic attraction between its positive and negative ions. The lattice energy of a ...

trends-in-lattice-energy-ion-size-and-charge

Trends in Lattice Energy: Ion Size and Charge

An ionic compound is stable because of the electrostatic attraction between its positive and negative ions. The lattice energy of a compound is a measure ...

Covalent Bonding and Lewis Structures

Compared to ionic bonds, which results from the transfer of electrons between metallic and nonmetallic atoms, covalent bonds result from the mutual ...

Electronegativity

Whether a bond is nonpolar or polar covalent is determined by a property of the bonding atoms called electronegativity.&#xA0;

Electronegativity values of ...

Ionization Energy

The amount of energy required to remove the most loosely bound electron from a gaseous atom in its ground state is called its first ionization energy ...

bond-polarity-dipole-moment-and-percent-ionic-character

Bond Polarity, Dipole Moment, and Percent Ionic Character

Bond Polarity

The absolute value of the difference in electronegativity (&Delta;EN) of two bonded atoms provides a rough measure of the polarity to be ...

Electron Affinity

The electron affinity (EA) is the energy change for adding an electron to a gaseous atom to form an anion (negative ion).



This process can be either ...

lewis-structures-of-molecular-compounds-and-polyatomic-ions

Lewis Structures of Molecular Compounds and Polyatomic Ions

To draw Lewis structures for complicated molecules and molecular ions, it is helpful to follow a step-by-step procedure as outlined:


	Determine the ...

Assembly of a Reflux System for Heated Chemical Reactions

Source: Laboratory of Dr. Philip Miller &#8212; Imperial College London
Many chemical experiments require elevated temperatures before any reaction is ...

Resonance

The Lewis structure of a nitrite anion (NO2&minus;) may actually be drawn in two different ways, distinguished by the locations of the N-O and N=O ...

Conducting Reactions Below Room Temperature

Source: Laboratory of Dr. Dana Lashley - College of William and Mary
Demonstration by: Matt Smith
When new bonds are formed in the course of a chemical ...

Formal Charges

In some cases, there are seemingly more than one valid Lewis structures for molecules and polyatomic ions. The concept of formal charges can be used to ...

Coordination Chemistry Complexes

Source: Laboratory of Dr. Neal Abrams &#8212; SUNY College of Environmental Science and Forestry
Transition metals are found everywhere from vitamin ...

Exceptions to the Octet Rule

Many covalent molecules have central atoms that do not have eight electrons in their Lewis structures. These molecules fall into three categories:


	...

determining-rate-laws-and-the-order-of-reaction

Determining Rate Laws and the Order of Reaction

Source: Laboratory of Dr. Neal Abrams &#8212; SUNY College of Environmental Science and Forestry
All chemical reactions have a specific rate defining the ...

Bond Energies and Bond Lengths

Stable molecules exist because covalent bonds hold the atoms together. The strength of a covalent bond is measured by the energy required to break it, ...

Determining the Empirical Formula

Source: Laboratory of Dr. Neal Abrams - SUNY College of Environmental Science and Forestry
Determining the chemical formula of a compound is at the heart ...

Bonding in Metals

Metallic bonds are formed between two metal atoms. A simplified model to describe metallic bonding has been developed by Paul Dr&#xFC;de called the ...

determining-the-solubility-rules-of-ionic-compounds

Determining the Solubility Rules of Ionic Compounds

Source: Laboratory of Dr. Neal Abrams &#8212; SUNY College of Environmental Science and Forestry
An ionic compound&#39;s solubility can be determined via ...

atomic-radii-and-effective-nuclear-charge

Atomic Radii and Effective Nuclear Charge

The elements in groups of the periodic table exhibit similar chemical behavior. This similarity occurs because the members of a group have the same number ...

Introduction to Catalysis

Source: Laboratory of Dr. Ryan Richards &#8212; Colorado School of Mines
Catalysis is among the most important fields of modern technology and presently ...

Ionic Radii

Ionic radius is the measure used to describe the size of an ion. A cation always has fewer electrons and the same number of protons as the parent atom; it ...

Introduction to Titration

Source: Laboratory of Dr. Yee Nee Tan &#8212; Agency for Science, Technology, and Research
Titration is a common technique used to quantitatively ...

Le Ch&#226;telier's Principle

Source: Laboratory of Dr. Lynne O&#39;Connell &#8212; Boston College
When the conditions of a system at equilibrium are altered, the system responds in ...

Preparing Anhydrous Reagents and Equipment

Source: Laboratory of Dr. Dana Lashley - College of William and Mary
Demonstrated by: Timothy Beck and Lucas Arney
Many reactions in organic chemistry are ...

Proton Exchange Membrane Fuel Cells

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
The United States consumes a large amount of energy &#8211; the current ...

Solutions and Concentrations

Source: Laboratory of Dr. Michael Evans &#8212; Georgia Institute of Technology
A solution is a homogeneous mixture containing some components in small ...

spectrophotometric-determination-of-an-equilibrium-constant

Spectrophotometric Determination of an Equilibrium Constant

Source: Laboratory of Dr. Michael Evans &#8212; Georgia Institute of Technology
The equilibrium constant, K, for a chemical system is the ratio of product ...

using-differential-scanning-calorimetry-to-measure-changes-in-enthalpy

Using Differential Scanning Calorimetry to Measure Changes in Enthalpy

Source: Laboratory of Dr. Terry Tritt &#8212; Clemson University
Differential Scanning Calorimetry (DSC) is a method of thermodynamic analysis based on ...

Source: Hsin-Chun Chiu and Tyler J. Morin, laboratory of Dr. Ian Tonks&#8212;University of Minnesota Twin Cities
Schlenk lines and high vacuum lines are ...

Construct and revise an explanation for the outcome of a simple chemical reaction based on the outermost electron states of atoms, trends in the periodic table, and knowledge of the patterns of chemical properties.

Chemical Equations

Chemical equations represent the identities and relative quantities of substances involved in a chemical reaction. The substances undergoing reaction are ...

Chemical Reactions in Aqueous Solutions

Chemical substances interact in many different ways. Certain chemical reactions exhibit common patterns of reactivity. Due to the vast number of chemical ...

Precipitation Reactions

In a precipitation reaction, aqueous solutions of soluble salts react to give an insoluble ionic compound &#x2013; the precipitate. The reaction occurs ...

Oxidation-Reduction Reactions

Oxidation&ndash;Reduction Reactions

Earth&rsquo;s atmosphere contains about 20% molecular oxygen, O2, a chemically reactive gas that plays an essential ...

Oxidation Numbers

In redox reactions, the transfer of electrons occurs between reacting species. Electron transfer is described by a hypothetical number called the ...

Acids, Bases and Neutralization Reactions

An acid-base reaction is one in which a hydrogen ion, H+, is transferred from one chemical species to another. Such reactions are of central importance to ...

Synthesis and Decomposition Reactions

Synthesis and decomposition are two types of redox reactions. Synthesis means to make something, whereas decomposition means to break something. The ...

Develop a model to illustrate that the release or absorption of energy from a chemical reaction system depends upon the changes in total bond energy.

HS-PS1-4.

Reaction Rate

The rate of reaction is the change in the amount of a reactant or product per unit time. Reaction rates are therefore determined by measuring the time ...

Measuring Reaction Rates

Polarimetry finds application in chemical kinetics to measure the concentration and reaction kinetics of optically active substances during a chemical ...

Concentration and Rate Law

The rate of a reaction is affected by the concentrations of reactants. Rate laws (differential rate laws) or rate equations are mathematical expressions ...

Determining Order of Reaction

Rate laws describe the relationship between the rate of a chemical reaction and the concentration of its reactants. In a rate law, the rate constant k and ...

the-integrated-rate-law-the-dependence-of-concentration-on-time

The Integrated Rate Law: The Dependence of Concentration on Time

While the differential rate law relates the rate and concentrations of reactants, a second form of rate law called the integrated rate law relates ...

Apply scientific principles and evidence to explain how the rate of a physical or chemical change is affected when conditions are varied.

Air-Free Solvent Transfer by Vacuum

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