2-Ethyl-5-methylpyrazine

Bromination using NBS has been used to provide acetylpyrazine derivatives from the corresponding ethylpyrazines. Bromination of 2-ethyl-3-methylpyrazine gives 2-bromoethyl-3-methylpyrazine in quantitative yield this may be oxidized using the sodium salt of 2-nitropropane or with pyridine AT-oxide to yield 2-acetyl-3-methylpyrazine in yields of 66 and 25% respectively (Scheme 14). 

Conversion of pyrazinones into bromopyrazines is known (82MI2), as is side-chain bromination, particularly when NBS is used under conditions conducive to radical formation. Thus, 2-ethyl-3-methylpyrazine was converted into the l -bromoethyl derivative (72JOC511). 

Ethyl-3-methylpyrazine (3-Ethyl-2-met hylpy razine) C2H5 ch3... 

Sizer at al. (20) observed that the compounds causing the pleasant odor which resembled bread crust occur in the basic volatile fraction of white bread. Identification experiments yielded the five pyrazines listed in Table II. A comparison of the odor threshold of each pyrazine in water to its concentration found in bread indicated that 2-ethyl-3-methylpyrazine and 2-methyl-6-propylpyrazine were present at concentrations above their odor thresholds. The authors described the odors of these two pyrazines as "butterscotch, nutty" and "burnt, butterscotch" notes (Table II). 

Ethyl-3-methylpyrazine 122.17/C7H10N2/ colorless to slightly yel s—prop glycol, veg 1 mL in 1... 

Ethyl-3-methyl-5-phenyl-2(177)-pyrazinone 5-Ethyl-3-methyl-2-pyrazinamine 1-oxide 2-Ethyl-3-methylpyrazine... 

ETHYL-3-METHYLPYRAZINE see ENF200 3 ETHYL-6-METHYLPYRIDINE see EOSOOO... 

Some 2 -dialkylpyrazines have been oxidized in one step with sodium dichromate in acetic acid, in good yields, to the corresponding 2-acyl-3-alkylpyrazines (678). Thus 2-ethyl-3-methylpyrazine gave 2-acetyl-3-methylpyrazine, 23-diethylpyrazine gave 2-acetyl-3-ethylpyrazine, and 2-ethyl-3,5(or 3,6)-dimethylpyrazine gave 2-acetyl-3,5(or 3,6)-dimethylpyrazine (678). 

Halogenations with A/-halogenosuccinimides have also been studied. Treatment of 2-methyl- and 2,5-dimethylpyrazine with one equivalent of A -chlorosuccinimide and a small quantity of benzoyl peroxide gave the unstable 2-chloromethyl (679, 690) and 2-chloromethyl-5-methylpyrazine (679). 2-Ethyl-3-methylpyrazine and 23-diethylpyrazine with V-bromosuccinimide in the presence of benzoyl peroxide gave 2-(l -bromoethyl)-3-methyl(and 3-ethyl)pyrazine, respectively (691,692). 

Pyrazine, 2-ethyl-3-methyl-, 2-ethyl-3-methylpyrazine [15707-23-0] FEMA 3155... 

The synthesis has been described in a patent of Polak s Frutal Works and Douwe Egberts (1968) by application of a scheme used for the preparation of acetylpyridines (Kolloff and Hunter, 1941). The corresponding monocarboxylate is condensed with ethyl acetate in the presence of anhydrous sodium ethoxide, and the condensation product then hydrolyzed with aqueous hydrochloride. Another procedure has been applied by Mookherjee and Klaiber (1972) who treated 2-ethyl-3-methylpyrazine (0.8) successively with A-bromosuccinimide and the sodium salt of 2-nitropropane or pyridine 1 -oxide (66% overall yield). Another method has been published by Wolt (IFF, 1975a). 

Ethyl-3-methylpyrazine 213 2-Hydroxy-3,5,5-trimethyl-2- cyclohex-l-one 261 Menthyl acetate... 

Ethyl hexyl acetate Ethyl isovalerate Ethyl lactate 2-Ethyl-3-methylpyrazine p-Ethylphenol... 

Ethyl lactate Ethyl laurate Ethyl levulinate Ethyl maltol Ethyl 2-methyl butyrate Ethyl methylphenylglycidate 2-Ethyl-3-methylpyrazine Ethyl 3-(methylthio) propionate Ethyl myristate Ethyl nitrite Ethyl 2-nonynoate Ethyl octanoate Ethyl oleate Ethyl oxyhydrate Ethyl pelargonate p-Ethylphenol Ethyl phenylacetate Ethyl-4-phenylbutyrate Ethyl phenylglycidate Ethyl-... 

Others. For example, the odour of 2,5-dimethylpyrazine resembles roasted hazelnuts, and 2,6-dimethylpyrazine and trimethylpyrazine have a chocolate-like odour. Important components of coffee aroma include a number of pyrazines, such as 2,3-diethyl-3-methylpyrazine, 2-ethyl-3,5-dimethylpyrazine, 2,6-dimethyl-3-vinylpyrazine and 2-ethyl-6-methyl-3-vinylpyrazine. The flavour-active components of popcorn and white bread are acetylpyrazine, 2-ethyl-3-methylpyrazine, 3-ethyl-2,5-dimethylpyrazine and 5-methyl-6,7-dihydro-5H-cyclopenta[fo] pyrazine. Cyclopentapyrazines, specihcaUy 6,7-dihydro-5H-cyclopenta[fo]pyrazines, are formed in reactions of cyclopen-tenolones with aminoketones and ammonia. 

Potato flavor is greatly influenced by methods of cooking or preparation. Raw potato contains the characteristic earthy aroma component, 2-ixo-propyl-3-methoxypyrazine. A character impact compound common to boiled and baked potatoes is methional (3-[methylthio]propanal). Baked potatoes contain Maillard products such as 2-ethyl-3-methylpyrazine (earthy, nutty) and 2-ethyl-6-vinylpyr-azine (buttery, baked potato) (34). In potato chips and French-fried potatoes, the potato flavor character of methional is modified by volatile aromatics from frying oils, such as ( , )-2,4-decadienal, and thermally generated alkyl oxazoles possessing lactone-like flavors (34,39). The pyrazines 2-ethyl-3,5-dimethyl and 2,3-diethyl-5-methylpyrazine are described as potato chip like (40). 

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