3958-79-0|Methyl 3,6-dioxocyclohexa-1,4-dienecarboxylate| Ambeed

GHS Pictogram:
Signal Word:	Warning
Hazard Statements:	H302-H315-H319
Precautionary Statements:	P501-P270-P264-P280-P302+P352-P337+P313-P305+P351+P338-P362+P364-P332+P313-P301+P312+P330

Yield	Reaction Conditions	Operation in experiment
98%	With magnesium(II) sulfate; silver(I) oxide; In diethyl ether; at 20℃; for 2.5h;Inert atmosphere;	10142] To a mixture of methyl 2,5-dihydroxybenzoate (i2.00 g, 69.4 mmol) and magnesium sulfate (24.00 g, i99.4 mmol) in abs. diethyl ether (i20 ml) under argon at room temperature was added finely pulverized silver(I) oxide (40. 52 g, i74.8 mmol), and the mixture was stirred at room temperature for 2.5 h. The reaction mixture was then filtered through Celite and concentrated under reduced pressure. In this way, without furtherpurification, methyl 3,6-dioxocyclo- hexa-i,4-diene-i-carboxylate (ii.50 g, 98% of theory) was obtained in the form of an orange crystalline solid. ‘H NMR (400 MHz, d6-DMSO ö, ppm) 7.i3 (s, iH), 6.86 (d, iH), 6.83 (d, iH), 3.93 (s, 3H). Titanium(IV) chloride (0.6i ml, 0.6i mmol) and titanium(IV) isopropoxide (0.i7 ml, 0.6i mmol) were added to degassed abs. dichloromethane (5 ml) in a baked-out round-bottom flask under argon at room temperature, and the mixture was stirred for iS minutes. The reaction mixture was then cooled to -78 C., a solution of methyl 3,6-dioxocyclohexa- i ,4-diene-i -carboxylate (203 mg, i .22 mmol) in abs. dichloromethane (5 ml) was slowly added dropwise, and the mixture was stirred at a temperature of-78 C. for 30 minutes. This was followed by the addition of i ,2-dimethoxy-4-propenylbenzene (220 mg, i .22 mmol), the reaction mixture was stirred at -78 C. for 3 hours and then warmed to room temperature within 4 hours, and a few drops of isopropanol and sat. sodium hydrogencarbonate solution were added. Afier repeated extraction of the aqueous phase with dichloromethane, the combined organic phases were dried over magnesium sulfate, filtered and concentrated under reduced pressure. Column chromatography purification (ethyl acetate/n-heptane gradient) of the remaining residue gave methyl 2-(3,4-dimethoxyphenyl)-5-hydroxy-3-me- thyl-2,3-dihydro-i -benzothran-4-carboxylate (347 mg, 82% of theory) in the form of a colorless solid. ‘H NMR (400 MHz, CDC13 ö, ppm) iO.55/iO.32 (br. s, iH, OH), 7.07 (d, iH), 6.86 (d, iH), 6.82 (m, 2H), 6.79 (s, iH), 5.26 (d, iH), 3.94 (s, 3H), 3.86 (s, 3H), 3.83 (s, 3H), 3.73 (m, iH), i.45 (d, 3H).
95%	With magnesium(II) sulfate; silver(I) oxide; In diethyl ether; at 25℃; for 1.5h;	General procedure: Silver oxide (3.0 mmol)And MgSO4 (3.0 mmol) were added1,4-dihydroxybenzene-2-carboxylate (1.0 mmol) in diethyl ether (20 mL)The resulting reaction solution was stirred at 25 C for 1.5 h,After filtration,The filtrate was concentrated to give the product.
	With potassium carbonate; In benzene;	5,8-Dimethoxy-2-methoxycarbonyl-4a,9,9a,10-tetrahydro-9,10-[1',2']benzeno-anthracene-1,4-dione (TT10) and 5,8-Dimethoxy-4a-methoxycarbonyl-9,9a,10-trihydro-9,10-[1',2']benzenoanthracene-1,4-dione (TT11): A mixture of 0.2 g (0.00119 mol) of methyl gentisate (14), 0.2 g (0.0014 mol) of potassium carbonate and 0.6 g (0.0026 mol) of silver oxide in 10 mL of benzene (freshly distilled) was stirred at 50 C. (bath temperature) under argon for 10 min under dark. The reaction mixture was cooled to room temperature, filtered through Celite, rinsed with small amount of ether, concentrated on a rotary evaporator and then under vacuum to give 0.198 g (100% yield) of methoxycarbonyl-1,4-benzoquinone (15); 1H NMR (CDCl3) d 7.13 (s, 1 H, C3 H), 6.84 (s, 2 H, C5,6 Hs), 3.92 (s, 3 H, OMe). The proton NMR spectrum indicates the material is about 100% pure and is used in the next step without purification. A solution of 73 mg (0.44 mmol) of 15and 70 mg (0.294 mmol) of 1,4-dimethoxyanthracene (1) in 1 mL of toluene was heated at 70 C. for 14 h and under reflux for 5 h under argon.

	With magnesium(II) sulfate; silver(I) oxide; In diethyl ether; at 20℃; for 6h;Inert atmosphere;	Freshly distilled Et2O (100 mL) was added to a 250 mL flask containing methyl 2,5-dihydroxybenzoate (1.68 g, 10 mmol) and anhydrous magnesium sulfate (3.0 g). Silver (I) oxide(6.9 g, 30 mmol) was added under argon. The resulting mixture was stirred for 6 h at room temperature. The mixture was then filtered through Celite, and the inorganic substances were washed several times with Et2O. The filtrate was concentrated in vacuo to give 1.64 g of the quinone quantitative yield.
	With silver(I) oxide;	2-(Methoxycarbonyl)-1,4-benzoquinone was prepared in two steps from 2,5-dihydroxybenzoic acid (first, methylation bydiazomethane; second, oxidation by Ag2O [9]). Physicochemical data for the synthesized quinones agreed with those in theliterature. We used Pinus sylvestris pine tar containing ~30% levopimaric acid that was collected in spring 2012 near NizhniiNovgorod. The levopimaric acid content in the pine tar was determined using GC and the ratio of methyl esters of totalresinous acids that were produced by methylating pine tar with an excess of diazomethane. The product yields were calculatedper starting quinone.

Precautionary Statements-General
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Prevention
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P220	Keep/Store away from clothing/combustible materials.
P221	Take any precaution to avoid mixing with combustibles
P222	Do not allow contact with air.
P223	Keep away from any possible contact with water, because of violent reaction and possible flash fire.
P230	Keep wetted
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P321
P322
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P378
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P391	Collect spillage. Hazardous to the aquatic environment
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P302 + P334	IF ON SKIN: Immerse in cool water/wrap in wet bandages.
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P304 + P340	IF INHALED: Remove victim to fresh air and Keep at rest in a position comfortable for breathing.
P304 + P341	IF INHALED: If breathing is difficult, remove victim to fresh air and keep at rest in a position comfortable for breathing.
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P307 + P311	IF exposed: call a POISON CENTER or doctor/physician.
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P309 + P311	IF exposed or if you feel unwell: call a POISON CENTER or doctor/physician.
P332 + P313	IF SKIN irritation occurs: Get medical advice/attention.
P333 + P313	IF SKIN irritation or rash occurs: Get medical advice/attention.
P335 + P334	Brush off loose particles from skin. Immerse in cool water/wrap in wet bandages.
P337 + P313	IF eye irritation persists: Get medical advice/attention.
P342 + P311	IF experiencing respiratory symptoms: call a POISON CENTER or doctor/physician.
P370 + P376	In case of fire: Stop leak if safe to Do so.
P370 + P378	In case of fire:
P370 + P380	In case of fire: Evacuate area.
P370 + P380 + P375	In case of fire: Evacuate area. Fight fire remotely due to the risk of explosion.
P371 + P380 + P375	In case of major fire and large quantities: Evacuate area. Fight fire remotely due to the risk of explosion.
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P401
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Disposal
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Alternative Products

Product Details of [ 3958-79-0 ]

Safety of [ 3958-79-0 ]

Application In Synthesis of [ 3958-79-0 ]

[ 3958-79-0 ] Synthesis Path-Upstream 1~1

[ 3958-79-0 ] Synthesis Path-Downstream 1~1

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Physical hazards
Code	Phrase
H200	Unstable explosive
H201	Explosive; mass explosion hazard
H202	Explosive; severe projection hazard
H203	Explosive; fire, blast or projection hazard
H204	Fire or projection hazard
H205	May mass explode in fire
H220	Extremely flammable gas
H221	Flammable gas
H222	Extremely flammable aerosol
H223	Flammable aerosol
H224	Extremely flammable liquid and vapour
H225	Highly flammable liquid and vapour
H226	Flammable liquid and vapour
H227	Combustible liquid
H228	Flammable solid
H229	Pressurized container: may burst if heated
H230	May react explosively even in the absence of air
H231	May react explosively even in the absence of air at elevated pressure and/or temperature
H240	Heating may cause an explosion
H241	Heating may cause a fire or explosion
H242	Heating may cause a fire
H250	Catches fire spontaneously if exposed to air
H251	Self-heating; may catch fire
H252	Self-heating in large quantities; may catch fire
H260	In contact with water releases flammable gases which may ignite spontaneously
H261	In contact with water releases flammable gas
H270	May cause or intensify fire; oxidizer
H271	May cause fire or explosion; strong oxidizer
H272	May intensify fire; oxidizer
H280	Contains gas under pressure; may explode if heated
H281	Contains refrigerated gas; may cause cryogenic burns or injury
H290	May be corrosive to metals
Health hazards
Code	Phrase
H300	Fatal if swallowed
H301	Toxic if swallowed
H302	Harmful if swallowed
H303	May be harmful if swallowed