Name: alkyne mass spectra and key peaks
Uploaded: 2024-12-05T18:32:20.000Z
Duration: 53 s
Channel: JoVE

Alkinler tipik olarak, rezonans stabilize edilmiş 3-propinil katyonu veya propargil katyonu oluşturmak üzere parçalanır.
Alkinler terminal veya dahili olabilir.
Terminal alkinlerde, 3-propinil katyon sinyali, 39'luk bir kütle-yük oranında görünür. İç alkinlerde, 3-propinil katyonu ikame edilir ve daha yüksek bir kütle-yük oranında görünür.
Sıklıkla gözlenen bir başka parçalanma türü, üçlü bağı taşıyan terminal alkin karbonundan hidrojen atomunun kaybıdır.
Bu nedenle, terminal alkinler, analit molekülünün moleküler iyonundan 1 u daha düşük bir kütle-yük oranında yoğun bir kütle sinyali sergiler. Bu tepe M-1 zirvesi olarak gösterilir.

kütle spektrometrisi: alkin parçalanması

Mass Spectrometry: Alkyne Fragmentation

Alkinlerin parçalanması tercihen alkin bağının α ve β karbonları arasındaki karbon-karbon bağında meydana gelir ve 3-propinil katyonu (veya propargil katyonu) oluşturur. Terminal alkinlerde, 3-propinil katyonu üreten tek parçalanma türü vardır. İkame edilmemiş 3-propinil katyonu, 39'luk bir kütle-yük oranında bir tepe noktası gösterir. İç alkinlerde, 3-propinil katyonu ikame edilir. Örneğin, 2-pentin, daha sonra 56'lık bir kütle-yük oranında bir kütle sinyali olarak ortaya çıkan metil-ikameli 3-propinil katyonuna parçalanır. 3-propinil katyonu rezonansla stabilize edilir ve karşılık gelen kütle sinyali, alkinlerin kütle spektrumunda yoğundur. Şekil 1, 1-pentinin bir etil radikaline ve rezonans stabilize edilmiş bir 3-propinil katyonuna parçalanmasını göstermektedir.

<img alt="Figure1" src="/files/ftp_upload/13045/13045-PT_Figure_1.svg" style="text-align: center; height: 115px;">

Şekil 1: 3-propinil katyonunu elde etmek için 1-pentinin moleküler iyonunun parçalanması.

Terminal alkinlerde gözlemlenen bir diğer parçalanma yolu, terminal sp karbonundan hidrojen kaybıdır. Bu, moleküler iyondan bir birim daha az kütle-yük oranına sahip bir kütle sinyaliyle sonuçlanır. Bu M–1 tepe noktası çok yoğundur ve birçok alkinin kütle spektrumunda temel tepe noktası haline gelir, bu nedenle alkinleri tanımlamak için kullanılabilir.

<img alt="Figure2" src="/files/ftp_upload/13045/13045-PT_Figure_2.svg" style="text-align: center; height: 275px;">

Şekil 2: 1-pentinin kütle spektrumu.

Kütle Spektrometrisi: Alkin Parçalanması

Alkinlerin parçalanması, tercihen, alkin bağının α ve β karbonu arasındaki karbon-karbon bağında meydana gelir ve bir ...

Education

JoVE Core

Analytical Chemistry

Analitik Kimya

Unit 1

Ünite 1

Mass Spectrometry Fragmentation Methods

Kütle Spektrometrisi Parçalanma Yöntemleri

KEY TERMS AND CONCEPTS

TEMEL TERİMLER VE KAVRAMLAR

alkyne mass spectra and key peaks

Alkyne mass spectra often show strong peaks from two main fragmentation paths. One path breaks the carbon-carbon bond between the alpha and beta carbons of the alkyne bond. This produces a 3-propynyl cation, also called a propargyl cation.

In terminal alkynes, this is the only fragmentation path that gives the 3-propynyl cation. The unsubstituted 3-propynyl cation appears at a mass-to-charge ratio of 39. In internal alkynes, the 3-propynyl cation is substituted. For example, 2-pentyne forms a methyl-substituted 3-propynyl cation, which gives a mass signal at m/z 56.

The 3-propynyl cation is resonance-stabilized. That stability makes its signal intense in the mass spectrum of alkynes. A related example is the fragmentation of 1-pentyne, which produces an ethyl radical and a resonance-stabilized 3-propynyl cation.

Terminal alkynes can also lose hydrogen from the terminal sp carbon. This gives a mass signal that is one unit less than the molecular ion. The M-1 peak is often very intense and can become the base peak in many alkyne mass spectra. Because of this, it can help identify alkynes, including 1-pentyne.

Alkyne Mass Spectra and Key Peaks

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mass spectrometry: alkyne fragmentation

Alkyne mass spectra often show strong peaks from two main fragmentation paths. One path breaks the carbon-carbon bond between the alpha and beta carbons of the alkyne bond. This produces a 3-propynyl cation, also called a propargyl cation. In terminal alkynes, this is the only fragmentation path that gives the 3-propynyl cation. The unsubstituted 3-propynyl cation appears at a mass-to-charge ratio of 39. In internal alkynes, the 3-propynyl cation is substituted. For example, 2-pentyne forms a...

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key terms and concepts

Learn how alkynes fragment in mass spectrometry, including the 3-propynyl cation, m/z 39 and 56 peaks, and the strong M-1 peak in terminal alkynes.

Alkyne Mass Spectra and Key Peaks | JoVE K12

JoVE Core Analitik Kimya, karmaşık kimyasal prensiplerini anlaşılır, ilgi çekici animasyonlara dönüştürerek basitleştirir ve SI Birimlerinden NMR spektroskopisine kadar konuları daha erişilebilir ve anlaşılır hale getirir. Buna ek olarak, bilim insanlarının yer aldığı videolar, bu kavramların dünya çapındaki laboratuvarlarda yürütülen gerçek dünya araştırmalarındaki uygulamalarını gösterir.

Alkyne Mass Spectra and Key Peaks

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