But 1 En 3 Yne

Mastering "But-1-en-3-yne": Navigating the Challenges of an Unsaturated Hydrocarbon

"But-1-en-3-yne," also known as vinylacetylene, is a fascinating and challenging molecule in organic chemistry. Its unique structure, containing both a carbon-carbon double bond (alkene) and a carbon-carbon triple bond (alkyne) in conjugation, leads to a rich and complex reactivity. Understanding its properties and behavior is crucial for students and researchers alike, as it serves as a building block in various synthetic pathways and exhibits interesting chemical behavior. This article aims to address common questions and challenges associated with understanding and working with but-1-en-3-yne.

I. Understanding the Structure and Nomenclature

But-1-en-3-yne’s name reveals its structure. "But" indicates a four-carbon chain. "1-en" signifies a double bond starting at carbon 1, and "3-yne" indicates a triple bond starting at carbon 3. Therefore, the structure is:

```
H2C=CH-C≡CH
1 2 3 4
```

This arrangement of conjugated double and triple bonds significantly influences its properties. The electron delocalization across the conjugated system leads to increased reactivity compared to isolated alkenes and alkynes. Note that the numbering starts from the end closer to the multiple bonds to give the lowest possible numbers.

II. Reactivity: Electrophilic and Nucleophilic Attacks

The conjugated system in but-1-en-3-yne makes it susceptible to both electrophilic and nucleophilic attacks.

A. Electrophilic Addition: Electrophiles preferentially attack the double bond due to its higher electron density compared to the triple bond. However, the reaction may not stop at the addition stage. The resulting carbocation can undergo further reactions, leading to a variety of products. For example, addition of HBr can lead to 1,2-addition (forming 1-bromo-but-2-ene) or 1,4-addition (forming 3-bromo-but-1-ene), depending on reaction conditions.

Step-by-step example (1,2-addition of HBr):

1. Protonation: The electrophilic proton (H⁺) from HBr adds to the carbon atom of the double bond, forming a carbocation intermediate.
2. Nucleophilic attack: The bromide ion (Br⁻) attacks the carbocation, forming 1-bromo-but-2-ene.

```
H2C=CH-C≡CH + HBr → CH3-CHBr-C≡CH
```

B. Nucleophilic Addition: Nucleophiles can attack either the carbon atom of the triple bond or the carbon atom of the double bond, depending on the reaction conditions and the nucleophile's strength. This usually requires the presence of a metal catalyst to activate the molecule.

III. Synthesis of But-1-en-3-yne

But-1-en-3-yne can be synthesized through various methods, often involving the coupling of smaller alkynes or the elimination reactions from suitable precursors. One common approach involves the reaction of acetylene with vinyl chloride. This reaction typically requires a strong base and specific conditions to control selectivity. Another method involves the dehydrohalogenation of suitable halogenated butenes. The precise synthetic route chosen depends on the desired yield and purity of the product.

IV. Applications and Importance

But-1-en-3-yne finds application in various fields, including:

Polymer Chemistry: It serves as a monomer in the production of synthetic rubbers and resins. Its conjugated system contributes to the desirable properties of these polymers.
Organic Synthesis: It's a valuable intermediate in the synthesis of more complex organic molecules. Its reactivity allows for diverse transformations.
Material Science: It is investigated for potential applications in the creation of novel materials with unique electronic and optical properties.

V. Safety Precautions

But-1-en-3-yne is a flammable and potentially toxic substance. Appropriate safety measures, including proper ventilation, personal protective equipment (PPE), and careful handling, are crucial when working with this compound.

Conclusion

But-1-en-3-yne presents a unique challenge in organic chemistry due to its conjugated diene-alkyne structure. Understanding its structure, reactivity, synthesis, and applications is essential for anyone working in related fields. By carefully considering the factors discussed in this article, researchers and students can better manage the challenges associated with this versatile molecule.

Frequently Asked Questions (FAQs):

1. What is the difference between 1,2-addition and 1,4-addition in the context of but-1-en-3-yne? 1,2-addition involves the addition of the electrophile and nucleophile across the double bond, while 1,4-addition involves addition across the conjugated system, with the electrophile adding to the double bond and the nucleophile adding to the carbon atom of the triple bond, four positions away.

2. Is but-1-en-3-yne chiral? No, but-1-en-3-yne is not chiral. It does not possess a chiral center (a carbon atom bonded to four different groups).

3. How is the purity of synthesized but-1-en-3-yne determined? Purity can be determined using various analytical techniques like gas chromatography (GC), nuclear magnetic resonance (NMR) spectroscopy, and infrared (IR) spectroscopy.

4. What are the major hazards associated with handling but-1-en-3-yne? The major hazards include flammability, toxicity (potential respiratory irritant and carcinogen), and potential for explosion under certain conditions.

5. What are some alternative names for but-1-en-3-yne? Other names include vinylacetylene and ethynyl ethylene.

Search Results:

Vinyl acetylene | C4H4 | CID 12720 - PubChem An estimated BCF of 10 was calculated for 1-buten-3-yne(SRC), using an estimated log Kow of 1.4(1) and a regression-derived equation(2). According to a classification scheme(3), this BCF suggests the potential for bioconcentration in aquatic organisms is low(SRC).

But-1-en-3-yne | Sigma-Aldrich - MilliporeSigma Find but-1-en-3-yne and related products for scientific research at MilliporeSigma

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Organic Nomenclature: But-1-en-3-yne or But-3-yne-1-en 11 Dec 2020 · Just wondering whether "but-1-en-3-yne" or "but-3-yne-1-en" follows the correct IUPAC naming convention for organic molecules. I'm going through a text book that uses the former in an example, but in the answer to one of the questions it uses the latter, so is it interchangeable or is one just wrong?

1-Buten-3-yne - NIST Chemistry WebBook IUPAC Standard InChIKey: WFYPICNXBKQZGB-UHFFFAOYSA-N Copy CAS Registry Number: 689-97-4 Chemical structure: This structure is also available as a 2d Mol file or as a computed 3d SD file The 3d structure may be viewed using Java or Javascript. Other names: But-1-en-3-yne; Butenyne; Ethene, ethynyl-; Monovinylacetylene; Vinylacetylene; 1-Butene-3-yne; 1-Butyn-3 …

Vinylacetylene | C4H4 - ChemSpider ChemSpider record containing structure, synonyms, properties, vendors and database links for Vinylacetylene, 689-97-4, butenyne, WFYPICNXBKQZGB-UHFFFAOYSA-N

But-1-en-3-yne | Sigma-Aldrich - MilliporeSigma Find but-1-en-3-yne and related products for scientific research at MilliporeSigma

butenyne (CHEBI:48088) - EMBL-EBI 3-buten-1-yne ChemIDplus monovinylacetylene

1-Buten-3-yne - NIST Chemistry WebBook The National Institute of Standards and Technology (NIST) uses its best efforts to deliver a high quality copy of the Database and to verify that the data contained therein have been selected on the basis of sound scientific judgment.

1-BUTEN-3-YNE | 689-97-4 - ChemicalBook 18 Dec 2024 · 1-BUTEN-3-YNE (CAS 689-97-4) information, including chemical properties, structure, melting point, boiling point, density, formula, molecular weight, uses, prices, suppliers, SDS and more, available at Chemicalbook.

1-Buten-3-yne - NIST Chemistry WebBook Other names: But-1-en-3-yne; Butenyne; Ethene, ethynyl-; Monovinylacetylene; Vinylacetylene; 1-Butene-3-yne; 1-Butyn-3-ene; 3-Buten-1-yne; Buten-3-yne; Ethynylethene; 1-Butenyne; Vinylethyne Permanent link for this species. Use this link for bookmarking this species for future reference. Information on this page: Gas phase thermochemistry data

1-buten-3-yne - 689-97-4, C4H4, density, melting point, boiling … 29 Apr 2024 · 1-buten-3-yne - cas 689-97-4, synthesis, structure, density, melting point, boiling point

Reaction of vinylacetylene (but-1-en-3-yne) with HCl 4 May 2020 · Beyond a shadow of a doubt, the second explanation, involving an allene rearrangement is the correct one. As you said, alkenes are more reactive towards electrophilic addition and hence the addition of HCl happens first on the double bond to give 3 …

The number of sigma and pi-bonds in 1-butene 3-yne are: - Toppr The number of sigma and pi-bonds in 1-butene 3-yne are 7 sigma and 3 pi. It has one C = C double bond which contains one pi bond. It has one C ≡ C triple bond which contains two pi bonds. It has 3 carbon carbon sigma bonds and 4 C−H pi bonds. Was this answer helpful?

But-1-en-3-yne;ethene | C6H8 | CID 141218091 - PubChem 6 Dec 2019 · But-1-en-3-yne;ethene | C6H8 | CID 141218091 - structure, chemical names, physical and chemical properties, classification, patents, literature, biological activities, safety/hazards/toxicity information, supplier lists, and more.

Vinylacetylene - Wikipedia Vinylacetylene is the organic compound with the formula C 4 H 4. The colourless gas was once used in the polymer industry. It is composed of both alkyne and alkene groups and is the simplest enyne.

What is the chemical structure of but-1-en-3-yne and how does 7 Feb 2025 · The chemical structure of but-1-en-3-yne is C4H6, with a triple bond between the first and third carbon atoms and a double bond between the first and second carbon atoms. This structure gives...

Buta-1,3-diene;but-1-en-3-yne | C8H10 | CID 141158161 - PubChem 6 Dec 2019 · Buta-1,3-diene;but-1-en-3-yne | C8H10 | CID 141158161 - structure, chemical names, physical and chemical properties, classification, patents, literature, biological activities, safety/hazards/toxicity information, supplier lists, and more.

But-1-en-3-yne;methane | C5H8 | CID 156766705 - PubChem 14 Oct 2021 · But-1-en-3-yne;methane | C5H8 | CID 156766705 - structure, chemical names, physical and chemical properties, classification, patents, literature, biological activities, safety/hazards/toxicity information, supplier lists, and more.

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but-1-en-3-yne properties - SpringerMaterials Properties appearing with but-1-en-3-yne boiling point centrifugal distortion chemical bond composition Coriolis coupling electric dipole moment equilibrium structure heat of sublimation internuclear distance molecular dipole moment molecular structure ...