3721-19-5

Basic information

• Product Name: 5-chlorobicyclo[2.2.1]hept-2-ene
• CAS NO: 3721-19-5
• Molecular Formula: C₇H₉Cl
• Molecular Weight: 128.5994
• Mol File: 3721-19-5.mol

Chemical Properties

• Boiling Point: 174.2°C at 760 mmHg
• Flash Point: 42.9°C
• Density: 1.13g/cm³
• Vapor Pressure: 1.63mmHg at 25°C
• Refractive Index: 1.53
• CAS DataBase Reference: 5-chlorobicyclo[2.2.1]hept-2-ene(CAS DataBase Reference)
• NIST Chemistry Reference: 5-chlorobicyclo[2.2.1]hept-2-ene(3721-19-5)
• EPA Substance Registry System: 5-chlorobicyclo[2.2.1]hept-2-ene(3721-19-5)

Safety Data

• Hazardous Substances Data: 3721-19-5(Hazardous Substances Data)

Usage

Uses

Used in Pharmaceutical Industry:
5-Chlorobicyclo[2.2.1]hept-2-ene serves as an intermediate in the synthesis of pharmaceuticals, contributing to the development of new medications and therapeutic agents.
Used in Agrochemical Industry:
5-chlorobicyclo[2.2.1]hept-2-ene is also utilized as an intermediate in the production of agrochemicals, playing a role in the creation of pesticides and other agricultural products to enhance crop protection and yield.
Used as a Reagent in Organic Synthesis:
5-Chlorobicyclo[2.2.1]hept-2-ene functions as a reagent in organic synthesis, facilitating various chemical reactions and the formation of different organic compounds for research and industrial applications.
Used as a Solvent in Industrial Processes:
In addition to its roles as an intermediate and reagent, 5-chlorobicyclo[2.2.1]hept-2-ene is employed as a solvent in a range of industrial processes, aiding in the dissolution and interaction of various substances.
It is crucial to handle 5-chlorobicyclo[2.2.1]hept-2-ene with care due to its potential to cause irritation to the skin, eyes, and respiratory system.

Upstream product

• 694-97-3 endo-5-norbornen-2-ol 
• 75-01-4 chloroethylene 
• 542-92-7 cyclopenta-1,3-diene 
• 740804-80-2 3-((1R,4S,7R)-Bicyclo[2.2.1]hept-2-en-7-yloxy)-3-chloro-3H-diazirine 

Downstream Products

• 498-66-8 norborn-2-ene 
• 279-19-6 nortricyclane 
• 21942-28-9 3-nortricyclyltrimethyltin 
• 21957-51-7 endo-2-norbornene-5-yl-trimethyl tin 

Relevant articles and documents

Endo entry to the nortricyclyl-norbornenyl cation system: Stereochemistry in the fragmentation of endo-5-norbornenyl-2-oxychlorocarbene

Fragmentation of (S)-endo-5-norbornenyl-2-oxychlorocarbene [(S)-8] in cyclohexane-d12 gives ～20% (S)-endo-2-chloro-5-norbornene [(S)-7] with ～50% ee, 65-70% (R)-exo-2-chloro-5-norbornene [(R)-4] with >95% ee, and ～12% (R)-3-nortricyclyl chloride [(R)-5] with ～22% ee. (Analogous stereochemical results were also obtained starting with the enantiomeric carbene (R)-8.) The (S)-8 to (S)-7 and (S)-8 to (R)-4 conversions are ascribed mainly to retention and inversion SNi transition states, respectively. These have been located by computational methods and are nearly isoenergetic. In more polar solvents (CDCl3 and CD3CN), the fragmentation of (S)-8 increasingly occurs via competitive ion pair pathways in which steroselectivity is diminished, and escape to the norbornenyl-nortricyclyl cation directs the products away from endo-2-chloro-5-norbornene toward exo-chloride 4 and nortricyclyl chloride 5.

Nortricyclyl-norbornenyl cation system accessed by carbene fragmentation

Fragmentation of nortricyclyloxychlorocarbene 5 in pentane occurs by an SNi-like process which yields nortricyclyl chloride 3g. In more polar solvents, fragmentation leads to nortricyclyl cation chloride anion pairs (9) that give mainly 3g, accompanied by ～10% of exo-2-norbornenyl chloride 4g. From exo-2-norbornenyloxychlorocarbene 6 in hydrocarbon solvents, "SNi" reactions lead mainly to exo- (4g) and endo-2-chloro-5-norbornenes (4g′). Leakage to ion pairs adds ～16% of nortricyclyl chloride 3g. In more polar solvents, the main product remains chloride 4g, but increasing quantities of 3g appear due to enhanced participation of ion pairs. Fragmentations of 5 and 6 in MeOH afford chlorides 3g and 4g as well as the corresponding methyl ethers 3b and 4b. Nortricyclyl cation and norbornenyl cation chloride anion pairs and methanol-solvated nortricyclyl cations are invoked to rationalize the results.

Unexpected interconnection of the 7-norbornenyl and 3-nortricyclcyl/5- norbornen-2-yl cations

Fragmentation of syn-7-norbornenyloxychlorocarbene provides products derived from both 7-norbornenyl cation-chloride anion pairs and from 3-nortricyclyl/2-norbornen-5-yl cation-chloride anion pairs. A 5,7-hydride shift within the 7-norbornenyl cation is proposed to interconnect the two cation systems.