21564-70-5

Basic information

• Product Name: Naphthalene, 1,4-dihydro-1-methyl-
• CAS NO: 21564-70-5
• Molecular Formula: C11H12
• Molecular Weight: 144.216
• Mol File: 21564-70-5.mol
• Article Data: 4

Chemical Properties

• CAS DataBase Reference: Naphthalene, 1,4-dihydro-1-methyl-(CAS DataBase Reference)
• NIST Chemistry Reference: Naphthalene, 1,4-dihydro-1-methyl-(21564-70-5)
• EPA Substance Registry System: Naphthalene, 1,4-dihydro-1-methyl-(21564-70-5)

Safety Data

• Hazardous Substances Data: 21564-70-5(Hazardous Substances Data)

Upstream product

• 65482-07-7 1,4-dihydronaphthalen-1-yltrimethylsilane 
• 4373-13-1 4-methyl-1,2-dihydronaphthalene 

Relevant articles and documents

Photochemistry of 3-methyl- and 4-methyl-1,2-dihydronaphthalene in solution

Photolysis of 3-methyl-1,2-dihydronaphthalene (3-MDHN) in hexane solution with 254-nm light produces one major product, 5-methylbenzobicyclo[3.1.0]hex-2-ene(5-MBBH; φ = 4.7 × 10-4). Photolysis in hexane in the presence of trifluoroacetic acid produces exclusively 2-methylene-1,2,3,4-tetrahydronaphthalene (2-MTHN). The 254-nm photolysis of 4-methyl-1,2-dihydronaphthalene (4-MDHN) in hexane produces 2-(o-tolyl)-1,3-butadiene (T13B; φ= 2.2 × 10-3), 1-methylbenzobicyclo[3.1.0]hex-2-ene (1-MBBH; φ= 1.4 × 10-3), 1 -methyl- 1,4-dihydronaphthalene (1-M-1,4-DHN; φ= 8.7 × 10-3), 1-methyltetralin (1-MT; φ= 1.5 × 10-3), and 1-methylnaphthalene (1-MN; φ= 2.7 × 10-3). Triplet sensitization of 4-MDHN produces only 1-MN in small amounts, suggesting that the direct photolyses proceed via singlet chemistry. The products appear to derive from a combination of electrocyclic opening of the cyclohexadienyl ring to generate an o-quinodimethane intermediate, disproportionation leading to net oxidation-reduction and, in 4-MDHN, a [1,3] hydrogen shift to form 1-M-1,4-DHN. The o-quinodimethane intermediates further react to form benzobicyclo[3.1.0]hex-2-ene derivatives (via a photochemical [4 + 2] cycloaddition; Scheme VI) and, in the case of 4-MDHN, the 1,3-butadiene T13B (via a thermal [1,5] hydrogen shift; Scheme VII).

The photochemical rearrangement of 1,2-dihydronaphthalenes into 1,4-dihydronaphthalenes induced by amines

The synthetic usefulness of the deprotonation/protonation reaction of excited 1,2-dihydronaphthalenes into 1,4-dihydronaphthalenes induced by amines has been investigated using 13 different substituted 1,2-dihydronaphthalenes and related compounds.The yield of the rearrangement ranges from 5 to 96percent.The formation of side-products depends on the position of protons in the substrate, which can be abstracted by the amine, and on competitive photoreactions.