Video Experimental Relacionado
Updated: Jun 30, 2026
07:28
Ethylene Polymerizations Using Parallel Pressure Reactors and a Kinetic Analysis of Chain Transfer Polymerization
Published on: November 27, 2015
Estudios sobre el mecanismo de la metátesis enina intermolecular: método cinético y efectos de los sustituyentes de
Brandon R Galan1, Anthony J Giessert, Jerome B Keister
1Department of Chemistry, University at Buffalo, the State University of New York, Buffalo, New York 14260-3000, USA.
Journal of the American Chemical Society
|April 21, 2005
Resumen
Las tasas de metástasis de Enyne aumentan con la sustitución de alquinos. El estudio sugiere un mecanismo de alquilideno primero e identifica los intermediarios de vinilcarbeno como limitadores de velocidad para reacciones específicas.
Área de la Ciencia:
- Química orgánica es la química orgánica.
- La catálisis de la catálisis.
- La cinética de la reacción.
Sus antecedentes:
- La metátesis de Enyne es una poderosa reacción de formación de enlaces carbono-carbono.
- Comprender su cinética es crucial para optimizar los procesos catalíticos.
Objetivo del estudio:
- Para investigar la cinética de reacción de las metástasis de enyne.
- Determinar la ley de velocidad para las reacciones específicas de metástasis cruzada alquino-alqueno.
Principales métodos:
- Se empleó espectroscopia infrarroja (IR) para monitorear el progreso de la reacción.
- Se realizaron estudios cinéticos para varias combinaciones de alquino-alqueno, incluida la metátesis cruzada de alquino-etileno y alquino-1-hexeno.
Principales resultados:
- Se encontró que las tasas de reacción aumentan con una mayor sustitución en el alquino.
- La quelación por ésteres propargílicos fue excluida como un factor significativo que influye en la velocidad de reacción.
- Las comparaciones de la tasa con los hidrocarburos alquinos apoyaron la exclusión de los efectos de quelación.
Conclusiones:
- Los hallazgos apoyan un mecanismo de primera reacción de alquilideno.
- Las especies de rutenio carbeno unidas a la fosfina se identificaron como estados de reposo.
- Los intermediarios de vinilo carbeno estuvieron implicados como el paso determinante de la velocidad en las metástasis de alquino-1-hexeno.
Más Videos Relacionados
Videos de Conceptos Relacionados
02:46E1 Reaction: Kinetics and Mechanism
Here, in contrast to the E2 reaction mechanism, we delve into the aspects of the E1 reaction mechanism, which has two steps: rate-limiting loss of the leaving group and abstraction of the beta hydrogen by a weak base. Typically, the experimental proof for the E1 mechanism is via kinetic studies or isotope studies. While the former demonstrates the first-order kinetics—the dependence of the reaction solely on substrate concentration—the latter proves the abstraction of hydrogen only in the...
02:37Structure and Physical Properties of Alkynes
Introduction:
In nature, compounds containing both carbon and hydrogen are known as "hydrocarbons". Aliphatic hydrocarbons are compounds whose molecules contain saturated single bonds (i.e., alkanes) or unsaturated double or triple bonds. Alkenes contain carbon–carbon double bonds and have a structural formula CnH2n. Unsaturated hydrocarbons containing carbon–carbon triple bonds are called "alkynes" and are structurally represented by the formula CnH2n-2.
The simplest alkyne is ethyne, or...
In nature, compounds containing both carbon and hydrogen are known as "hydrocarbons". Aliphatic hydrocarbons are compounds whose molecules contain saturated single bonds (i.e., alkanes) or unsaturated double or triple bonds. Alkenes contain carbon–carbon double bonds and have a structural formula CnH2n. Unsaturated hydrocarbons containing carbon–carbon triple bonds are called "alkynes" and are structurally represented by the formula CnH2n-2.
The simplest alkyne is ethyne, or...
02:27Preparation of Alkynes: Alkylation Reaction
Introduction
Alkylation of terminal alkynes with primary alkyl halides in the presence of a strong base like sodium amide is one of the common methods for the synthesis of longer carbon-chain alkynes. For example, treatment of 1-propyne with sodium amide followed by reaction with ethyl bromide yields 2-pentyne.
Alkylation of terminal alkynes with primary alkyl halides in the presence of a strong base like sodium amide is one of the common methods for the synthesis of longer carbon-chain alkynes. For example, treatment of 1-propyne with sodium amide followed by reaction with ethyl bromide yields 2-pentyne.
02:38Electrophilic Addition to Alkynes: Halogenation
Introduction
Halogenation is another class of electrophilic addition reactions where a halogen molecule gets added across a π bond. In alkynes, the presence of two π bonds allows for the addition of two equivalents of halogens (bromine or chlorine). The addition of the first halogen molecule forms a trans-dihaloalkene as the major product and the cis isomer as the minor product. Subsequent addition of the second equivalent yields the tetrahalide.
Halogenation is another class of electrophilic addition reactions where a halogen molecule gets added across a π bond. In alkynes, the presence of two π bonds allows for the addition of two equivalents of halogens (bromine or chlorine). The addition of the first halogen molecule forms a trans-dihaloalkene as the major product and the cis isomer as the minor product. Subsequent addition of the second equivalent yields the tetrahalide.
02:24Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation
Introduction
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.
02:10Reduction of Alkynes to trans-Alkenes: Sodium in Liquid Ammonia
Alkynes can be reduced to trans-alkenes using sodium or lithium in liquid ammonia. The reaction, known as dissolving metal reduction, proceeds with an anti addition of hydrogen across the carbon–carbon triple bond to form the trans product. Since ammonia exists as a gas (bp = −33°C) at room temperature, the reaction is carried out at low temperatures using a mixture of dry ice (sublimes at −78°C) and acetone.
When dissolved in liquid ammonia, an alkali metal, such as sodium, dissociates into a...
When dissolved in liquid ammonia, an alkali metal, such as sodium, dissociates into a...