Myrcene


Myrcene a hydrocarbon isolated from bayberry oil is a typical terpene  [c.1084]

The structural feature that distinguishes terpenes from other natural products is the iso prene unit The carbon skeleton of myrcene (exclusive of its double bonds) corresponds to the head to tail union of two isoprene units  [c.1084]

Fig. 2. Monoterpenes in hydrocarbon resins a-pinene [2437-95-8] (3), p-pinene [18172-67-3] (4), Hmonene [7705-14-8] (5), 3-carene [13466-76-9] (6), myrcene [123-35-3] (7), camphene [5794-03-6] (8), p-pheUandrene [555-10-2] (9), terpinolene [586-62-9] (10), and p-terpinene [99-86-5] (11). Fig. 2. Monoterpenes in hydrocarbon resins a-pinene [2437-95-8] (3), p-pinene [18172-67-3] (4), Hmonene [7705-14-8] (5), 3-carene [13466-76-9] (6), myrcene [123-35-3] (7), camphene [5794-03-6] (8), p-pheUandrene [555-10-2] (9), terpinolene [586-62-9] (10), and p-terpinene [99-86-5] (11).
Terpenes are characterized as being made up of units of isoprene in a head-to-tail orientation. This isoprene concept, invented to aid in the stmcture deterrnination of terpenes found in natural products, was especially useful for elucidation of stmctures of more complex sesquiterpenes, diterpenes, and polyterpenes. The hydrocarbon, myrcene, and the terpene alcohol, a-terpineol, can be considered as being made up of two isoprene units in such a head-to-tail orientation (1).  [c.408]

Dimerization of Isoprene. Isoprene is becoming an increasingly important raw material for the production of terpenes. For example, myrcene (7) can be produced by the dimerization of isoprene (2-methyl-1,3-butadiene) (42—44) and myrcene is very useful for synthesizing a number of oxygenated terpenes important in the flavor and fragrance industry.  [c.411]

The production of myrcene (7) from P-pinene is important commercially for the synthesis of a wide variety of flavor and fragrance materials. Some of those include nerol and geraniol, citroneUol (27) and citral (5).  [c.413]

Purified myrcene has minimal use in flavor and fragrance appHcations. Production and cost figures for cmde myrcene from P-pinene are not pubhshed to avoid disclosure of individual company operations, but the production volume is large (- SO, 000 t).  [c.416]

In the presence of the copper catalyst, myrcene (7) hydrochlorination proceeds initially to give predominately linalyl chloride (46), which then isomerizes to give about 40—50% neryl chloride, 50—55% geranyl chloride, and only 2—4% linalyl chloride. The cmde mixture of chlorides is converted to the mixture of acetates (or formates) by the addition of sodium acetate or sodium formate with a phase-transfer catalyst (PTC) (90). Saponification of the acetates or formates gives the alcohols and the sodium acetate or formate for recycle. Fractionation of the cmde alcohol mixture gives both nerol and geraniol products, usually as mixtures high purity products are made by further distillation. There are usually many grades of nerol and geraniol produced, depending on the customer requirements.  [c.416]

Myrcene with its conjugated diene system readily undergoes Diels-Alder reactions with a number of dienophiles. For example, reaction with 3-meth.5i-3-pentene-2-one with a catalytic amount of AlCl gives an intermediate monocyclic ketone, which when cyclized with 85% phosphoric acid produces the bicycHc ketone known as Iso E Super [54464-57-2] (49). The product is useful in providing sandalwood-like and cedarwood-like fragrance ingredients (91).  [c.417]

Reaction of myrcene and sulfur dioxide under pressure produces myrcene sulfone. This adduct is stable under ordinary temperatures and provides a way to stabilize the conjugated diene system in order to hydrate it with sulfuric acid. The myrcene sulfone hydrate produced is pyrolyzed in the vapor phase in order to regenerate the diene system to produce myrcenol [543-39-5] (50).  [c.417]

When butadiene is treated with PdCU the l-chloromethyl-7r-allylpalladium complex 336 (X = Cl) is formed by the chloropalladation. In the presence of nucleophiles, the substituted 7r-methallylpalladium complex 336 (X = nucleophile) is formed(296-299]. In this way, the nucleophile can be introduced at the terminal carbon of conjugated diene systems. For example, a methoxy group is introduced at the terminal carbon of 3,7-dimethyl-I,3,6-octatriene to give 337 as expected, whereas myrcene (338) is converted into the tr-allyl complex 339 after the cyclization[288].  [c.66]

E imination of geranyl acetate using Pd(0Ac)2 and PI13P is not regiose-lective[329]. Interestingly, the addition of an equivalent amount of propargyl-zinc bromide not only accelerates the elimination, but also gives high regioselectivity. A 75 25 mixture of trans- and tu-ocimene was obtained from geranyl acetate without producing any myrcene (497), while neryl acetate gave pure myrcene (497). An exclusive 4-elimination is observed[335],  [c.357]

In several important cases, new synthetic strategies have been developed into new production schemes. An outstanding example of this is the production of an entire family of terpene derivatives from a-pinene (29), the major component of most turpentines, via linalool (3) (12). Many of these materials had been produced from P-pinene, a lesser component of turpentine, via pyrolysis to myrcene and further chemical processing. The newer method offers greater manufacturing dexibiUty and better economics, and is environmentally friendly in that catalytic air oxidation is used to introduce functionality.  [c.85]

Uses ndReactions. Some of the principal uses for P-pinene are for manufacturing terpene resins and for thermal isomerization (pyrolysis) to myrcene. The resins are made by Lewis acid (usuaUy AlCl ) polymerization of P-pinene, either as a homopolymer or as a copolymer with other terpenes such as limonene. P-Pinene polymerizes much easier than a-pinene and the resins are usehil in pressure-sensitive adhesives, hot-melt adhesives and coatings, and elastomeric sealants. One of the first syntheses of a new fragrance chemical from turpentine sources used formaldehyde with P-pinene in a Prins reaction to produce the alcohol, Nopol (26) (59).  [c.413]

Myrcene Manufacture. An important commercial source for mycene is its manufacture by pyrolysis of p-piaene at 550—600°C (87). The thermal isomerization produces a mixture of about 75—77 wt % myrcene, 9% limonene, a small amount of T -limonene [499-97-8] and some decomposition products and dimers. The cmde mixture is usually used without purification for the production of the important alcohols nerol and geraniol. Myrcene may be purified by distillation but every precaution must be taken to prevent polymerization. The use of inhibitors and distillation at reduced pressures and moderate temperatures is recommended. Storage or shipment of myrcene in any purity should also include the addition of a polymerization inhibitor.  [c.416]

Uses ndReactions. The largest use of myrcene is for the production of the terpene alcohols nerol, geraniol, and linalool. The nerol and geraniol are further used as intermediates for the production of other large-volume flavor and fragrance chemicals such as citroneUol, dimethyloctanol, citroneUal, hydroxycitroneUal, racemic menthol, citral, and the ionones and methylionones.  [c.416]

Another synthesis of Lyral (51) consists of the reaction of myrcene with acrolein to give the myrac aldehyde [37677-14-8] (52). The aldehyde group, which is sensitive to acid hydration conditions with strong acids, has to be protected by formation of the morpholine enamine. The enamine is then hydrolyzed on workup after the acid-catalyzed hydration to produce Lyral (93—95).  [c.417]

Linalool can also be made along with nerol and geraniol via the hydrochlorination of myrcene. After conversion of the chlorides to acetates followed by saponification of the acetates, the mixture of alcohols is obtained. Fractionation of the mixture gives linalool in about 95% purity, but the presence of close boiling impurities prohibits manufacture of a perfiimery-quahty product.  [c.421]

A synthesis of optically active citroneUal uses myrcene (7), which is produced from P-piaene. Reaction of diethylamine with myrcene gives A/,A/-diethylgeranyl- and nerylamines. Treatment of the aHyUc amines with a homogeneous chiral rhodium catalyst causes isomerization and also induces asymmetry to give the chiral enamines, which can be readily hydrolyzed to (+)-citroneUal (151).  [c.423]


See pages that mention the term Myrcene : [c.268]    [c.182]    [c.1084]    [c.482]    [c.654]    [c.306]    [c.307]    [c.308]    [c.309]    [c.310]    [c.313]    [c.321]    [c.321]    [c.321]    [c.322]    [c.324]    [c.329]    [c.331]    [c.331]    [c.334]    [c.334]    [c.335]    [c.336]    [c.337]    [c.337]    [c.337]    [c.338]    [c.338]    [c.339]    [c.409]    [c.417]   
Carey organic chemistry (0) -- [ c.1084 ]

Organic chemistry (0) -- [ c.1084 ]

The chemistry of essential oils and artificial perfumes Volume 2 (1922) -- [ c.77 ]