Name: alcohol tests for primary, secondary, and tertiary
Uploaded: 2020-03-26T07:22:29.000Z
Duration: 3 min 32 s
Channel: JoVE

K12 Standards

Florida Department of Education

High School

Physical Science

SC.912.P.8

SC.912.P.8.13

Identifying Alcohols

الكحوليات هي فئة من الجزيئات العضوية تمتلك مجموعة وظيفية هيدروكسيل واحدة على الأقل متصلة بذرة كربون. الميثانول والإيثانول نوعان من الكحول المألوف. كلاهما كحول أليفاتي ، مما يعني أنهما مشتقان من هيدروكربون ولا يحتويان على مجموعة بنزين. 
هناك ثلاثة تصنيفات للكحول الأليفاتي. الأول هو الكحول الأولي ، حيث ترتبط مجموعة الهيدروكسيل بذرة كربون متصلة بمجموعة واحدة من الكربون أو الألكيل. في الكحول الثانوي ، ترتبط مجموعة الهيدروكسيل بذرة كربون تحتوي على مجموعتين من الألكيل. أخيرا ، في الكحول الثلاثي ، ترتبط مجموعة الهيدروكسيل بذرة كربون بثلاث مجموعات ألكيل. 
يمكن أن تكون الكحوليات أيضا عطرية ، حيث يتم توصيل مجموعة الهيدروكسيل مباشرة بالكربون في حلقة البنزين. أبسط شكل من أشكال الكحول العطري هو الفينول. تعرف المركبات التي تحتوي على الفينول بمشتقات الفينول أو الفينولات. 
يمكن استخدام بعض ردود الفعل التي يمر بها الكحول لتمييزها بناء على الاختلافات الواضحة في نتيجة التفاعل. أحد هذه التفاعلات هو اختبار كلوريد الحديديك ، الذي يختبر وجود الفينولات. عندما يضاف كلوريد الحديديك إلى الفينول ، يتشكل مركب أرجواني من الحديد وثلاثة الفينول. لا يتم ملاحظة ذلك عند إضافته إلى الكحول الأليفاتي. 
رد فعل مفيد آخر هو اختبار جونز ، والذي يستخدم لتحديد الكحوليات الأليفاتية الأولية والثانوية. كاشف جونز ، وهو مزيج من حمض الكبريتيك وثالث أكسيد الكروم في الماء ، هو عامل مؤكسد قوي. يتفاعل مع الكحولات الأولية لتكوين الألدهيدات - التي تشكل بعد ذلك أحماض كربوكسيل - ويتفاعل مع الكحولات الثانوية لتكوين الكيتونات. تؤدي إضافة كاشف جونز إلى الكحوليات الأولية والثانوية إلى تغيير لون المحلول من البرتقالي إلى الأخضر الداكن. لا تتفاعل الكحوليات الثلاثية مع كاشف جونز لأنها مقاومة للأكسدة. 
أخيرا ، يمكننا التمييز بين الكحوليات الأليفاتية من خلال اختبار لوكاس. يتفاعل كاشف لوكاس ، وهو خليط من كلوريد الزنك وحمض الهيدروكلوريك ، مع الكحوليات الثانوية والثالثية من خلال تفاعل استبدال S N 1. ينسق كلوريد الزنك مع أكسجين الهيدروكسيل لتوليد مجموعة مغادرة ممتازة. بمجرد التخلص منها ، يبقى الكربوكيتاشن موجب الشحنة. بعد ذلك ، يهاجم أيون الكلور الكربوكاتيون لتكوين كلوريد الألكيل ، وهو غير قابل للذوبان في الماء ويبدو غائما. 
تتفاعل الكحوليات الثلاثية على الفور مع كاشف لوكاس لتشكيل طبقة زيتية في درجة حرارة الغرفة. تعطي الكحوليات الثانوية نتيجة إيجابية بعد بضع ثوان إلى بضع دقائق. تعطي الكحوليات الأولية نتيجة سلبية ما لم يتم تسخينها. 
في هذا المختبر ، ستستخدم اختبار كلوريد الحديديك واختبار جونز واختبار لوكاس لتحديد الكحول غير المعروف.

التعرف على الكحول

<h4>الكحول</h4>
الكحوليات هي مركبات عضوية من بين أكثر المركبات شهرة ومألوفة ، حيث أن لها تطبيقات واستخدامات واسعة النطاق في الحياة اليومية. الكحوليات هي جزيئات عضوية تحتوي على مجموعة وظيفية هيدروكسيل متصلة بمجموعة ألكيل أو أريل (ROH). إذا كان كربون الهيدروكسيل يحتوي على مجموعة R واحدة فقط ، فإنه يعرف باسم الكحول الأساسي. إذا كانت تحتوي على مجموعتين R ، فهي كحول ثانوي ، وإذا كانت تحتوي على ثلاث مجموعات R ، فهي كحول من الدرجة الثالثة. مثل العديد من المركبات العضوية الأخرى ، يمكن أن تكون الكحوليات عطرية أيضا من خلال احتوائها على حلقة البنزين. أبسط كحول عطري هو الفينول. 
يمكن تحديد الكحول في الكيمياء العضوية من خلال استغلال الخصائص المختلفة لأنواع الكحول. بينما يمكن استخدام طرق تحليل الأجهزة المختلفة ، مثل الرنين المغناطيسي النووي (NMR) ، يمكن أيضا استخدام اختبارات نوعية أخرى. من خلال اقتران هذه الاختبارات معا ، يمكن تحديد هوية الكحول بطريقة مماثلة للطريقة التي يمكن بها التعرف على الألدهيدات والكيتونات. 
<h4>اختبار كلوريد الحديديك</h4>
تتمثل إحدى طرق التفريق بين الكحول الأليفاتي والكحول العطري في استخدام كلوريد الحديد (III). يعطي مركب كلوريد الحديد المحلول مظهرا أحمر برتقالي. في وجود كحول عطري ، مثل الفينول ، يتم استبدال ذرات الكلوريد بالكحول العطري ، مما يؤدي إلى تغيير خاصية التنسيق لذرة الحديد المركزية. هذا يغير لون المحلول إلى اللون الأرجواني. لن تتفاعل الكحوليات الأليفاتية مع كلوريد الحديد (III) ، وبالتالي ، يظل المحلول أحمر برتقالي. 
<h4>اختبار جونز</h4>
يستخدم اختبار جونز ثالث أكسيد الكروم في وجود حمض الكبريتيك ليكون بمثابة عامل مؤكسد قوي. في وجود كاشف جونز ، يتم تحويل الكحول الأولي أولا إلى ألدهيد ثم إلى حمض كربوكسيلي ، بينما يتأكسد الكحول الثانوي إلى كيتون. حالة أكسدة الكروم هي مفتاح هذا الاختبار. الكروم في حالة الأكسدة +6 في كاشف جونز. تعطيه مجمعات Cr (VI) في الكاشف لونه البرتقالي المحمر الفاتح. 
في عملية التفاعل ، يتم تقليل الكروم من Cr (VI) إلى حالة الأكسدة +3 - Cr (III). أولا ، يشكل الكحول وحمض الكروميك إستر كرومات. بعد ذلك ، تشق القاعدة (H 2 O) رابطة C-H للكحول ، وتشكل مجموعة الكربونيل مع تقليل Cr (VI) إلى Cr (IV). يخضع كربون الكحول لأكسدة 2 إلكترون ، ويخضع الكروم (IV) لتخفيض 2 إلكترون ، لذا فهذه خطوة أكسدة اختزال 
يشارك Cr (IV) في خطوات الأكسدة الإضافية ويتم تقليله في النهاية إلى Cr (III). غالبا ما يكون Cr (III) موجودا كأيونات سداسي الأكوكروميوم (III) — [Cr (H }2 O) 6 ] 3+ — و Cr (III) ، حيث يتم استبدال جزيئات H 2 O بواحد أو أكثر من أيونات الكبريتات — [Cr (H } 2 O) 5 (SO 4)] +. تعطي هذه المجمعات Cr (III) اللون الأخضر المميز. 
لا تتفاعل الكحوليات الثلاثية مع الكروم ، وبالتالي لا يتم إنتاج أي راسب ، مما يحافظ على المحلول برتقاليا. لذلك ، يمكن أن يساعد اختبار جونز في التمييز بين الكحول الأولي والثانوي والكحول من الدرجة الثالثة. 
<h4>Lucas Test</h4>
يستخدم اختبار لوكاس كلوريد الزنك (II) في وجود حمض الهيدروكلوريك ككاشف. في حالة وجود كحول ، سيقوم كاشف لوكاس بهلوجين الكحول ، مما يجعل منتجا غير قابل للذوبان في المحاليل المائية. يعتمد معدل التفاعل لهذا بشكل كبير على تكوين الكربوكيتاشن الناجم عن فقدان الهيدروكسيل كماء. الكربوهيدرات التي يتكون من الكحول الأولي غير مستقرة ، وبالتالي لن تحدث بسهولة. ينتج عن هذا عدم وجود تفاعل ملحوظ في درجة حرارة الغرفة. سيشكل الكحول الثلاثي كربوهيدرات مستقرة ، مما يؤدي إلى رد فعل سريع عند إضافة كاشف لوكاس. ينتج عن هذا ظهور مرحلة ثانية في خليط التفاعل لأن المنتج المهلجنة النهائي غير قابل للذوبان في الماء. ستشكل الكحوليات الثانوية كربوهيدرات أقل استقرارا من الكحوليات الثلاثية ، لكن التفاعل سيحدث في درجة حرارة الغرفة في غضون دقائق. لذلك ، يمكن أن يساعد اختبار لوكاس في التمييز بين الكحول الأولي والثانوي والثالثي. 
<h4>المراجع</h4>
<ol>
	<li style="font-size:17px">Streitwieser ، A. ، Heathcock ، C.H. ، Kosower ، E.M. (1998). مقدمة في الكيمياء العضوية. نهر السرج العلوي ، نيوجيرسي: قاعة برنتيس. </li>
</ol>

الكحول
الكحول هي مركبات عضوية من بين أكثر المركبات شهرة ومألوفة ، حيث أن لها تطبيقات واستخدامات واسعة النطاق في الحياة اليومية ...

Education

JoVE Lab Manual

Chemistry

الكيمياء

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 behavior instead of relying only on instrument-based methods such as NMR. By combining several qualitative tests, the identity of an alcohol can be determined in a way similar to how aldehydes and ketones are identified.

The ferric chloride test helps tell aromatic alcohols from aliphatic alcohols. Iron(III) chloride starts as a red-orange solution. If an aromatic alcohol such as phenol is present, the chloride atoms are replaced and the solution turns purple. Aliphatic alcohols do not react in this test, so the color stays red-orange.

The Jones test uses chromium trioxide with sulfuric acid as a strong oxidizing reagent. A primary alcohol is oxidized first to an aldehyde and then to a carboxylic acid. A secondary alcohol is oxidized to a ketone. Chromium starts in the +6 oxidation state, which gives the reagent its reddish-orange color, and is reduced to Cr(III), which is green. Tertiary alcohols do not react, so the solution remains orange. This makes the Jones test useful for separating primary and secondary alcohols from tertiary alcohols.

The Lucas test uses zinc(II) chloride in hydrochloric acid. It halogenates the alcohol and produces an insoluble product in water. The test depends on carbocation formation when the hydroxyl group leaves as water. Primary alcohols do not show a visible reaction at room temperature because their carbocations are unstable. Tertiary alcohols react quickly because their carbocations are more stable, and a second layer appears. Secondary alcohols react more slowly and usually take a few minutes. This test helps distinguish primary, secondary, and tertiary alcohols.

Alcohol Tests for Primary, Secondary, and Tertiary

alcohol-tests-for-primary-secondary-and-tertiary

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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 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

Comprehensive, curriculum-focused videos for both instructors and students in introductory chemistry lab courses.

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Learn how ferric chloride, Jones, and Lucas tests distinguish aromatic, primary, secondary, and tertiary alcohols using color change and reaction rate.

Alcohol Tests for Primary, Secondary, and Tertiary | JoVE K12

استعد لتدريس التعرف على الكحول من خلال هذا الدليل الإرشادي للمدرسين لمدة 7 دقيقة. يغطي خطوات التحضير الأساسية لمختبر Chemistry على JoVE Lab Manual.

تحضير المدرّس لـ التعرف على الكحول في Chemistry - أكثر من 13K مشاهدة | JoVE Lab Manual

اتبع إجراءات التعرف على الكحول خطوة بخطوة في فيديو بروتوكول الطالب هذا لمدة 12 دقيقة. جزء من مجموعة Chemistry على JoVE Lab Manual.

بروتوكول الطالب لـ التعرف على الكحول في Chemistry - أكثر من 87K مشاهدة | JoVE Lab Manual

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, ...

States of Matter

Solids, liquids, and gases are the three states of matter commonly found on Earth. A solid is rigid and possesses a definite shape. A liquid flows and ...

States of Matter and Phase Changes

The internal energy of a substance&#8212;the total kinetic energy of all its molecules and the potential energy of their associated forces&#8212;depends ...

molecular-comparison-of-gases-liquids-and-solids

Molecular Comparison of Gases, Liquids, and Solids

Particles in a solid are tightly packed together (fixed shape) and often arranged in a regular pattern; in a liquid, they are close together with no ...

Differentiate between physical and chemical properties and physical and chemical changes of matter.

SC.912.P.8.1

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 ...

Phase Transitions

Whether solid, liquid, or gas, a substance&#39;s state depends on the order and arrangement of its particles (atoms, molecules, or ions). Particles in the ...

phase-transitions-vaporization-and-condensation

Phase Transitions: Vaporization and Condensation

The physical form of a substance changes on changing its temperature. For example, raising the temperature of a liquid causes the liquid to vaporize ...

Vapor Pressure

When a liquid vaporizes in a closed container, gas molecules cannot escape. As these gas phase molecules move randomly about, they will occasionally ...

Clausius-Clapeyron Equation

The equilibrium between a liquid and its vapor depends on the temperature of the system; a rise in temperature causes a corresponding rise in the vapor ...

Phase Transitions: Melting and Freezing

Heating a crystalline solid increases the average energy of its atoms, molecules, or ions, and the solid gets hotter. At some point, the added energy ...

phase-transitions-sublimation-and-deposition

Phase Transitions: Sublimation and Deposition

Some solids can transition directly into the gaseous state, bypassing the liquid state, via a process known as sublimation. At room temperature and ...

Heating and Cooling Curves

When a substance&#8212;isolated from its environment&#8212;is subjected to heat changes, corresponding changes in temperature and phase of the substance ...

Phase Diagrams

A phase diagram combines plots of pressure versus temperature for the liquid-gas, solid-liquid, and solid-gas phase-transition equilibria of a substance. ...

SC.912.P.8.2

The Atomic Theory of Matter

The earliest recorded discussion of the basic structure of matter comes from ancient Greek philosophers. Leucippus and Democritus argued that all matter ...

Subatomic Particles

Dalton was only partially correct about the particles that make up matter. All matter is composed of atoms, and atoms are composed of three smaller ...

The Wave Nature of Light

The nature of light has been a subject of inquiry since antiquity. In the seventeenth century, Isaac Newton performed experiments with lenses and prisms ...

The Electromagnetic Spectrum

The electromagnetic spectrum consists of all the types of electromagnetic radiation arranged according to their frequency and wavelength. Each of the ...

Interference and Diffraction

Interference is a characteristic phenomenon exhibited by waves. When two electromagnetic waves interact with their peaks and troughs coinciding, a ...

Photoelectric Effect

When light of a particular wavelength strikes a metal surface, electrons are emitted. This is called the photoelectric effect. The minimum frequency of ...

The Bohr Model

Following the work of Ernest Rutherford and his colleagues in the early twentieth century, the picture of atoms consisting of tiny dense nuclei surrounded ...

Emission Spectra

When solids, liquids, or condensed gases are heated sufficiently, they radiate some of the excess energy as light. Photons produced in this manner have a ...

The de Broglie Wavelength

In the macroscopic world, objects that are large enough to be seen by the naked eye follow the rules of classical physics. A billiard ball moving on a ...

The Uncertainty Principle

Werner Heisenberg considered the limits of how accurately one can measure properties of an electron or other microscopic particles. He determined that ...

The Quantum-Mechanical Model of an Atom

Shortly after de Broglie published his ideas that the electron in a hydrogen atom could be better thought of as being a circular standing wave instead of ...

Explore the scientific theory of atoms (also known as atomic theory) by describing changes in the atomic model over time and why those changes were necessitated by experimental evidence.

SC.912.P.8.3

Elements: Chemical Symbols and Isotopes

A chemical symbol is an abbreviation used to indicate an element or an atom of an element. For example, the symbol for mercury is Hg. The same symbol is ...

Ions and Ionic Charges

In ordinary chemical reactions, the nucleus &mdash; which contains the protons and neutrons of each atom and thus identifies the element &mdash; remains ...

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 ...

Atomic Mass

Atoms &mdash; and the protons, neutrons, and electrons that compose them &mdash; are extremely small. For example, a carbon atom weighs less than 2 ...

Atomic Number and Mass Number

The number of protons in the nucleus of an atom is its atomic number (Z). This is the defining trait of an element. Its value determines the identity of ...

Explore the scientific theory of atoms (also known as atomic theory) by describing the structure of atoms in terms of protons, neutrons and electrons, and differentiate among these particles in terms of their mass, electrical charges and locations within the atom.

SC.912.P.8.4

Periodic Classification of the Elements

The periodic table arranges atoms based on increasing atomic number so that elements with the same chemical properties recur periodically. When their ...

Electron Configurations

Electron configurations and orbital diagrams can be determined by applying the Aufbau principle (each added electron occupies the subshell of lowest ...

Electronic Structure of Atoms


An atom comprises protons and neutrons, which are contained inside the dense, central&#160;core called the nucleus, with electrons present around the ...

Electron Behavior

Electrons are negatively charged subatomic particles that are attracted to an orbit around the positively-charged nucleus of an atom. They reside in ...

Relate properties of atoms and their position in the periodic table to the arrangement of their electrons.

SC.912.P.8.5

A. A working definition of matter is that it takes up space, has mass, and has measurable properties. Matter is comprised of atomic, subatomic, and elementary particles.

B. Electrons are key to defining chemical and some physical properties, reactivity, and molecular structures. Repeating (periodic) patterns of physical and chemical properties occur among elements that define groups of elements with similar properties. The periodic table displays the repeating patterns, which are related to the atom's outermost electrons. Atoms bond with each other to form compounds.

C. In a chemical reaction, one or more reactants are transformed into one or more new products. Many factors shape the nature of products and the rates of reaction. 

D. Carbon-based compounds are building-blocks of known life forms on earth and numerous useful natural and synthetic products.

Alcohol Tests for Primary, Secondary, and Tertiary

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