Name: separating mixtures with solvent extraction
Uploaded: 2020-03-26T07:22:28.000Z
Duration: 2 min 55 s
Channel: JoVE

추출은 혼합물에서 성분을 분리하는 기술입니다. 추출에 대해 이미 잘 알고 계실 것입니다. 차를 우려낼 때마다 찻잎에서 카페인과 향료와 같은 수용성 화합물을 뜨거운 물로 추출할 수 있습니다. 이것은 고체-액체 추출의 예입니다.
액체-액체 추출은 혼합물이 두 개의 혼합되지 않는 액체 상으로 용해되는 또 다른 유형의 추출입니다. 용매는 혼합되지 않아야 하며, 이는 혼합되지 않고 별도의 상임을 의미합니다. 액체-액체 추출은 분리 깔때기에서 수행되어 밀도가 높은 용매는 바닥에 가라앉고 밀도가 낮은 용매는 맨 위에 놓입니다. 그런 다음 각 용질 화합물은 가장 용해되는 상으로 이동합니다. 따라서 극성이 다른 용매를 선택하는 것이 중요합니다.
일반적으로 비극성 용질은 유기상으로 분할되고 극성 용질은 수성상으로 분할됩니다. 분배 계수 K는 유기상의 용질 농도와 수성상의 용질 농도의 비율입니다. 용질이 분리되면 두 개의 서로 다른 상이 수집됩니다. 두 단계 모두에서 각 구성 요소의 잔류물이 있을 가능성이 있음을 명심하십시오.
산-염기 추출은 용해도 차이에 따라 산성 화합물과 염기성 화합물을 분리하는 특별한 유형의 액체-액체 추출입니다. 산은 물에 용해될 때 양성자를 제공하는 화합물이고 염기는 양성자를 받아들이는 화합물이라는 것을 기억하십시오.
산성 화합물을 분리하기 위해 혼합물에 염기가 첨가됩니다. 염기는 산성 화합물에서 양성자를 받아 이온 성으로 만듭니다. 반대로, 산을 첨가하면 양성자가 염기성 화합물로 전달됩니다. 두 경우 모두 이온 화합물은 수성상으로 전달되고 중성 화합물은 유기상으로 분할됩니다. 이온 화합물을 수집한 다음 탈양성자화 또는 재양성자화하여 원래 화합물로 다시 변환합니다.
이 실험실에서는 셀룰로오스, 벤조산 및 카페인의 혼합물을 분리합니다. 먼저 추출 및 여과를 사용하여 셀룰로오스를 분리합니다. 그런 다음 산-염기 추출을 수행하여 벤조산과 카페인을 분리합니다.

추출

추출
추출은 표적 화합물을 분리하기 위해 유기 화학에서 사용되는 일반적인 기술입니다. 추출 공정에서 용질은 한 상에서 다른 상으로 전달되어 반응하지 않은 출발 물질 또는 불순물로부터 분리됩니다. 추출은 끓는점이 높은 용매와 같이 증발로 제거하기 어려운 반응 용매에서 용질을 쉽게 분리하는 데에도 사용됩니다.<span style="color: rgb(0, 0, 0); 글꼴 패밀리 : Roboto, RobotoDraft, Helvetica, Arial, sans-serif; 글꼴 크기 : 13px; 글꼴 스타일 : 일반; font-variant-ligatures : 일반; 글꼴 변형 캡 : 보통; 글꼴 두께 : 400; 문자 간격 : 보통; 고아: 2명; 텍스트 정렬 : 시작; 텍스트 들여 쓰기 : 0px; 텍스트 변환 : 없음; white-space: pre-wrap; 과부: 2명; 단어 간격 : 0px; -webkit-text-stroke-width: 0px; 배경색 : RGB (255, 255, 255); 텍스트 장식 스타일 : 초기; 텍스트 장식 색상 : 초기; display: inline !important; 플로트: 없음;" > 일반적으로 추출에는 세 가지 유형이 있습니다. 첫째, 고액 추출에서 용질은 고체상에서 액상으로 전달됩니다. 액체-액체 추출에서 용질은 한 액체에서 다른 액체로 전달됩니다. 산-염기 추출에서 용질은 이온 화합물로 변형되어 유기상에서 수성상으로 전달됩니다. 추출의 일반적인 예는 커피 또는 차를 추출하는 것입니다. 카페인, 식물 풍미 및 냄새를 포함하는 고체상은 뜨거운 물에 의해 액체 상태로 추출됩니다.
액체-액체 추출
액체-액체 추출은 수성상에 용해된 유기 화합물을 유기 용매로 전달하거나, 미반응 반응물, 염 및 기타 수용성 불순물을 수성상으로 전달하면서 관심 유기 화합물을 유기상에 남겨두는 데 사용됩니다. 비혼화성 액체는 완전히 혼합되어도 결코 균질한 용액을 형성하지 않는 액체입니다. 대신, 비혼화성 액체는 기름과 물과 같은 다른 상으로 분리됩니다.
액체-액체 추출은 수성상에 용해된 유기 화합물을 유기 용매로 전달합니다. 액체-액체 추출을 수행하기 위해 먼저 용질을 포함하는 수용액을 분리 깔때기에 첨가합니다. 그런 다음, 비수용성 유기 용매를 분리 깔때기에 첨가합니다. 깔때기의 내용물이 잘 혼합되면 유기 화합물은 수성상보다 유기상에서의 용해도가 더 높기 때문에 유기상으로 분할됩니다.
두 용매는 혼합되지 않기 때문에 두 액체는 밀도가 높은 액체가 바닥에 있고 밀도가 낮은 액체가 위에 있는 별도의 층을 형성합니다. 두 단계가 다시 두 개의 층으로 정착하면 분리 깔때기 하단의 스톱콕을 열고 한 층이 흘러나오도록 하여 분리합니다. 용질이 제거된 액체를 라피네이트라고 하고, 용질을 얻은 액체를 추출물이라고 합니다.
유기 화합물은 각 상에서의 용해도에 따라 두 층 사이에서 분할됩니다. 평형은 용질의 화학적 전위가 두 단계에서 동일할 때 도달합니다. 용질에 대한 분배 계수 K는 유기층의 시료 농도를 수성상의 농도로 나눈 비율입니다. 분배 계수는 용질과 추출에 사용된 용매 쌍 모두에 따라 달라지는 상수입니다. 분배 계수는 두 용매 각각에 대한 용질의 선호도를 나타내는 표현입니다. 분배 계수가 큰 용질은 유기 용매 층으로 추출되는 경향이 더 높습니다. 분배 계수가 작은 용질은 수성상으로 전이하는 것을 선호합니다.
액체-액체 추출에 사용할 용매 쌍을 결정하는 것은 중요한 단계입니다. 사용할 용매를 선택할 때 다음 사항을 고려하십시오. 첫째, 용질은 물보다 용매에 더 잘 용해되어야 합니다. 따라서 잠재적인 용매 쌍에서 용질의 분배 계수를 아는 것이 필요합니다. 둘째, 용매 쌍은 물과 혼합되지 않아야 하며 혼합될 때 균일한 용액을 형성하지 않아야 합니다. 셋째, 용매는 불활성이어야 하며 용질과 반응하지 않아야 합니다. 용매는 또한 용질에서 쉽게 제거될 수 있도록 휘발성이어야 합니다. 물과 혼합되지 않는 유기 용매는 일반적으로 무극성 또는 낮은 극성을 가지고 있습니다.
또한 상층과 하부층의 동일성을 결정하기 위해 용매의 밀도를 아는 것도 중요합니다. 염소화 유기 용제를 제외한 대부분의 유기 액체는 물보다 밀도가 낮으며 분리 깔때기의 바닥에 침전됩니다.
산-염기 추출
산-염기 추출은 산-염기 특성에 따라 유기 화합물을 분리하는 액체-액체 추출의 한 유형입니다. 용질이 산 또는 염기인 경우 pH가 변함에 따라 전하가 변합니다. 일반적으로 대부분의 유기 화합물은 중성이므로 물보다 유기 용매에 더 잘 용해됩니다. 그러나 유기 화합물이 이온성이되면 물에 더 잘 용해됩니다. 이는 유기 상에서 수성 상으로 유기산 또는 염기 화합물을 추출하는 데 유용합니다.
산-염기 추출은 용질을 수용성 염 형태로 변형시켜 용해도를 변화시킴으로써 이러한 특성을 활용합니다. 유기 화합물과 그 염의 용해도는 기술이 효과적이기 위해 극적으로 달라야 합니다.
예를 들어, 유기 카르복실산, 아민 및 중성 화합물을 포함하는 혼합물을 생각해 보십시오. 6개 이상의 탄소로 구성된 카르복실산은 물에 불용성이며 유기 용매에 완전히 용해됩니다. 그러나 그들의 공액 염기(이온 화합물)는 수용성이며 유기 용매에 불용성입니다. 적어도 7개의 탄소로 구성된 아민은 물에는 녹지 않지만 유기 용매에는 용해됩니다. 그 아민 (이온 성 화합물)의 공액 산은 물에 용해되며 유기 용제에 불용성입니다.
염기와 반응하면 카르복실산이 염 형태로 중화됩니다. 혼합물의 다른 화합물은 중성을 유지합니다. 카르복실산이 염으로 변형되면 수성상으로 분할되고 중성 화합물은 유기상에 남아 있습니다.
산-염기 추출은 pKa에서 상당한 차이가 있는 두 개의 약한 산 또는 두 개의 약한 염기를 분리하는 데에도 사용됩니다. 산의 경우, pKa 값이 작은 상대적으로 강한 산은 약한 염기를 사용하여 염으로 중화됩니다. 약한 염기는 약한 산과 효율적으로 반응하지 않으며 더 강한 산 만 염으로 변형됩니다. 그런 다음, 소금은 추출하는 동안 수성상으로 추출됩니다. 이 과정은 상대적으로 더 강한 염기가 약산을 사용하여 염으로 중화되는 약한 염기에 대해서도 유사하게 진행됩니다.
참조
<ol>
	<li style="font-size:17px">Harris, D.C. (2015). 정량적 화학 분석. 뉴욕, 뉴욕 : WH 프리먼 앤 컴퍼니.</li>
</ol>

추출
추출은 표적 화합물을 분리하기 위해 유기 화학에서 사용되는 일반적인 기술입니다. 추출 과정에서 용질이 옮겨집니다 ...

Education

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JoVE Lab Manual

Chemistry

화학

Extraction

separating mixtures with solvent extraction

Solvent extraction is a common way to separate and isolate a target compound in organic chemistry. In this process, a solute moves from one phase to another so it can be separated from unreacted starting materials or impurities. Extraction is also useful when a product is dissolved in a reaction solvent that is hard to remove by evaporation, such as a solvent with a high boiling point.

There are three main types of extraction. In solid-liquid extraction, the solute moves from a solid phase into a liquid phase. In liquid-liquid extraction, the solute moves from one liquid into another. In acid-base extraction, the solute is changed into an ionic compound and moved from an organic phase into an aqueous phase. A familiar example is brewing coffee or tea, where hot water extracts caffeine, plant flavors, and odors from the solid material.

Liquid-liquid extraction is used when an organic compound is dissolved in water or when water-soluble impurities need to be removed from an organic product. It works with immiscible liquids, which are liquids that do not form one uniform solution, even after mixing. Oil and water are a common example. To carry out this extraction, the aqueous solution is placed in a separatory funnel, and a non-water-soluble organic solvent is added. After mixing, the compound partitions into the phase where it is more soluble.

Because the two liquids are immiscible, they separate into layers after settling. The denser liquid forms the bottom layer, and the less dense liquid stays on top. The layers are then separated by opening the stopcock at the bottom of the separatory funnel and letting one layer drain out. The layer that loses the solute is called the raffinate, and the layer that gains the solute is called the extract. At equilibrium, the solute has the same chemical potential in both phases.

The partition coefficient, K, describes how a solute divides between the two layers. It is the concentration in the organic layer divided by the concentration in the aqueous layer. This value depends on the solute and the solvent pair used. A large partition coefficient means the solute prefers the organic layer. A small partition coefficient means the solute prefers the aqueous layer. Choosing the right solvent pair is important, so the solute should be more soluble in that solvent than in water, the two solvents should be immiscible, and the solvents should be inert and volatile. The water-immiscible organic solvent is usually non-polar or low in polarity.

Knowing density is also important because it tells which layer is on top and which is on the bottom. Most organic liquids are less dense than water and rise to the top, although chlorinated organic solvents are an exception and can settle to the bottom. Acid-base extraction is a special type of liquid-liquid extraction that separates organic compounds based on acid-base behavior. When pH changes, the charge on an acid or base can change too. Neutral organic compounds are usually more soluble in organic solvents, but ionic forms are more soluble in water.

This property lets chemists turn an organic acid or base into a water-soluble salt. The salt and the neutral compound must have very different solubilities for the method to work well. For example, a mixture may contain an organic carboxylic acid, an amine, and a neutral compound. Carboxylic acids with six carbons or more are insoluble in water and soluble in organic solvents, but their conjugate bases are water-soluble and insoluble in organic solvents. Amines with at least seven carbons are insoluble in water and soluble in organic solvents, while their conjugate acids are water-soluble and insoluble in organic solvents.

When a base is added, the carboxylic acid is neutralized to its salt form, while the other compounds remain neutral. The salt then moves into the aqueous phase, and the neutral compounds stay in the organic phase. Acid-base extraction can also separate two weak acids or two weak bases when their pKa values are far enough apart. For weak acids, the stronger acid with the smaller pKa is converted to a salt using a weak base, while the weaker acid is not reacted much. The same idea applies to weak bases, but a weak acid is used to neutralize the stronger base.

Separating Mixtures with Solvent Extraction

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balmer series

Hydrogen Emission Lines

Hydrogen emission lines show how electrons move between fixed energy levels in the Bohr model. Niels Bohr proposed this model for the hydrogen atom in 1913. In this model, an electron can only occupy certain orbits, and it cannot exist between them. These energy states are labeled with the quantum number n. The ground state is n = 1. Higher values, such as n = 2, 3, 4, and so on, are excited states. An electron changes state only by absorbing or emitting energy equal to the difference between...

beer's law

Absorbance Spectra and Beer-Lambert Analysis

Absorbance spectra and the Beer-Lambert Law show how light can be used to study molecules in solution. When light hits a substance, it may be absorbed, transmitted, or reflected. A substance often interacts with a range of wavelengths, and each wavelength can affect the molecules or atoms in a different way. When a molecule absorbs light, that energy can be used for translation, vibration, rotation, or electron excitement. Electron excitement is especially important in spectroscopy because it...

concentration dependence

Reaction Order and Rate Constants

Chemical kinetics describes the speed of a chemical reaction. The rate depends on the reaction mechanism, the complexity of the reaction, and the number of reactants involved. Reactant concentration also affects how fast a reaction happens. The rate law is the experimental relationship that connects these factors to reaction rate. In the rate law, each reactant contributes through a reaction order. The general form is r = k[A]^m[B]^n for aA + bB + ... → cC. Here, r is the reaction rate, k is...

temperature dependence

Reaction Rate, Arrhenius, and Catalysts

Chemical kinetics explains how fast a reaction happens and why that speed changes. The reaction rate is the speed of a chemical reaction. It is defined as the change in concentration of a reactant or product over time. Reaction speed depends on several factors, including the concentration of the reactants and the temperature of the reaction. Each reactant affects the rate in a specific way. That relationship is described by the rate law. The rate law is an equation that connects the...

galvanic cells

Battery Power from Redox Reactions

Electrochemistry studies how chemical change and electrical energy are linked. In this branch of chemistry, electrons move from one species to another. That movement can either produce current or be driven by an applied current. The main reaction in electrochemistry is the oxidation-reduction, or redox, reaction. A redox reaction has two half-reactions. Oxidation is the loss of electrons, and reduction is the gain of electrons. These changes also shift the oxidation state of each substance. The...

electrolytic cells

Electroplating with Electrolytic Cells

Electrochemistry links electrical energy with chemical change, and electrolytic cells show how electricity can drive a nonspontaneous reaction. In these reactions, electrons move from one species to another. The key chemistry is a redox reaction, or oxidation-reduction reaction, which happens in two half-reactions. Oxidation is the loss of electrons, and reduction is the gain of electrons. The substance that loses electrons is the reducing agent, and the substance that gains electrons is the...

proper lab notebook keeping

Recording a Reproducible Lab Experiment

Accurate lab notebook records are essential in science and organic chemistry labs. Without clear notes, descriptions, quantities, and observations, an experiment cannot be repeated or checked. Good record keeping supports reproducibility, which means other people can follow the same work and get similar results. A laboratory notebook is useful in school labs, research settings, and industry. It can also become a legal record when an idea, process, substance, or technique is patented and...

basic organic chemistry techniques

Organic Lab Glassware and Safe Handling

Organic chemistry labs use specific glassware, careful weighing steps, and controlled heating to keep reactions safe and accurate. Beakers and Erlenmeyer flasks are often used for mixing or holding solvents, but they are not meant for measuring volume unless only an approximate amount is needed. Volumetric glassware is used when a precise volume matters. This group includes graduated cylinders, volumetric pipettes, and volumetric flasks. A graduated cylinder is commonly used in the organic lab...

melting points

How Impurities Change Melting Points

Melting point helps identify an organic compound by showing the temperature where a solid turns into a liquid at 1 atmosphere of pressure. It is a physical property, like solubility, density, color, and electronegativity. Because the exact start of melting is hard to measure, the result is reported as a range. The lower end is when the first drops of liquid appear. The upper end is when the last solid has melted. Scientists compare this range with literature values to help identify a compound. <br...

boiling points

Boiling Point and Vapor Pressure

Boiling point and vapor pressure are key physical properties of a liquid. For a pure compound, the boiling point can help identify the substance. In experiments, the boiling point is usually recorded as a range because exact values are hard to measure and may differ by a few degrees from the literature value. Vapor pressure explains why a liquid boils. In a sealed container, some molecules at the liquid surface gain enough energy to escape into the gas phase. At the same time, some gas...

recrystallization

Purifying Crystals by Solubility

Purifying crystals by solubility is a key organic chemistry technique. Recrystallization uses differences in solubility to separate a desired solid product from starting materials, solvent, and impurities. It is one of the three standard purification methods, along with distillation and extraction. Solubility is the maximum amount of a substance that can dissolve in a fixed volume of solvent at a given temperature. Different solutes dissolve in different solvents, and their behavior can vary...

extraction

Solvent extraction is a common way to separate and isolate a target compound in organic chemistry. In this process, a solute moves from one phase to another so it can be separated from unreacted starting materials or impurities. Extraction is also useful when a product is dissolved in a reaction solvent that is hard to remove by evaporation, such as a solvent with a high boiling point. There are three main types of extraction. In solid-liquid extraction, the solute moves from a solid phase...

simple distillation

Separating Liquids by Boiling Point

Separating liquids by boiling point is the goal of distillation. A miscible mixture contains liquids that mix evenly, and it can be heated so that the more volatile liquid evaporates first. Volatility is a liquid’s tendency to vaporize, and boiling begins when bubbles form in the liquid phase. In a closed container, liquid and vapor can reach equilibrium, which means the rate of vaporization equals the rate of condensation. The pressure from the vapor above the liquid is called vapor pressure.

steam distillation

Steam Distillation and Low-Boiling Separation

Steam distillation is a separation method for temperature-sensitive organic compounds. It works best when the organic compound is immiscible in water, meaning the two liquids do not mix. The method helps remove the organic molecule from a non-volatile contaminant without using the higher temperatures needed for many other separations. In steam distillation, the immiscible mixture is heated until both water and the volatile organic compound distill together. The vapor rises to a condenser,...

thin-layer chromatography

TLC Separation by Polarity

Thin-layer chromatography (TLC) separates compounds in a mixture by polarity. It uses the same basic parts as other chromatography methods: a stationary phase, a mobile phase, and the solute. In TLC, the stationary phase is a thin coating on a plate instead of material packed into a column. The stationary phase in most TLC systems is polar silica gel, a form of silicon dioxide. Its surface has OH groups that can form hydrogen bonds. The sample is first spotted on a pencil start line with a...

column chromatography

Separating Mixtures by Polarity

Column chromatography separates compounds in an organic chemistry lab by using differences in physical properties. It is especially useful for microscale separations when less than 10 grams of material is available for analysis. The method can separate a mixture based on solubility, polarity, hydrophobicity, size, and charge. Any chromatography system has three main parts: the stationary phase, the mobile phase, and the sample mixture. In column chromatography, the stationary phase is usually...

hydrolysis of an ester

Soap Formation from Triglycerides

Triglycerides are lipids made of a glycerol backbone linked to three fatty acids. They are common in vegetable oils and animal fats. Plant lipids are the basis of vegetable oils, while animal lipids are used as lard or general sources of fats. A fatty acid has a long carbon chain, usually between 12 and 20 carbons, with a weak organic acid at one end. Some fatty acids contain double bonds. These are unsaturated fats. The double bond usually gives the chain a bent, cis shape. As a result,...

synthesis of luminol

Luminol Chemiluminescence in Forensics

Luminol chemiluminescence shows how a chemical reaction can produce light and help with blood detection. Chemical reactions may be endothermic or exothermic, depending on whether they absorb or release heat as reactants become products. The enthalpy of a reaction is the energy difference between reactants and products, or ΔH. A positive ΔH means the reaction is endothermic. A negative ΔH means it is exothermic. Many reactions do not happen in a single step. They can pass through intermediates...

esterification

Ester Formation and Everyday Fragrances

Esters are organic compounds with a carbonyl group attached to an oxygen that connects to another alkyl or aryl group. Their general formula is RCOOR'. They are often made by reacting a carboxylic acid with an alcohol in an esterification reaction. In this process, the hydroxyl group of the acid is replaced by an alkyl or aryl group. Many simple esters have familiar fruit and flower smells because their structures are small and less complex. Formic acid and methanol can combine to form methyl...

identification of unknown aldehydes and ketones

identification-of-unknown-aldehydes-and-ketones

Carbonyl Tests for Aldehydes and Ketones

Aldehydes and ketones are carbonyl compounds, which means they contain a C=O functional group. A ketone has two alkyl or aryl groups attached to the carbonyl carbon. Acetone is the simplest ketone, with two methyl groups. An aldehyde is similar, but it has at least one hydrogen attached to the carbonyl carbon. Formaldehyde is the simplest aldehyde, and acetaldehyde has one hydrogen and one methyl group. The carbonyl carbon in both aldehydes and ketones is electrophilic because the oxygen atom...

uv-vis spectroscopy of dyes

How Dyes Absorb Visible Light

Dyes absorb visible light because their molecular structure lets them interact with specific wavelengths. When light hits a substance, some light is absorbed and the rest is reflected or transmitted. The color we see depends on the wavelength that is reflected. A blue substance reflects blue light, around 430 to 480 nm, and absorbs the complementary orange region, around 590 to 630 nm. Compounds that do not absorb in the visible range appear colorless to the human eye. Light also has energy and...

identifying alcohols

Alcohol Tests for Primary, Secondary, and Tertiary

Alcohol tests can help sort alcohols by structure and reactivity. Alcohols are organic molecules with a hydroxyl group attached to an alkyl or aryl group, written as ROH. If the carbon with the hydroxyl group has one R group, the alcohol is primary. If it has two R groups, it is secondary. If it has three R groups, it is tertiary. Alcohols can also be aromatic when they contain a benzene ring. Phenol is the simplest aromatic alcohol. To identify an alcohol, chemists can use its chemical...

chemistry

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Learn how solvent extraction separates mixtures in organic chemistry, including liquid-liquid extraction, separatory funnels, partition coefficients, and acid-base extraction.

Separating Mixtures with Solvent Extraction | JoVE K12

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Separating Mixtures with Solvent Extraction

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