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I thought it would be easy to find info on something as common as alpha-methylstyrene. Looked on altavista and in the Merck without any luck, so anything like its CAS#, B.P., etc. would be much appreciated! Thanks! 8)
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http://www.chemicalland21.com/arokorhi/industrialchem/functional%20Monomer/ALPHA-METHYLSTYRENE.htm (http://www.chemicalland21.com/arokorhi/industrialchem/functional%20Monomer/ALPHA-METHYLSTYRENE.htm)
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Shit! Didn't there used to be a synthesis of a-methylstyrene on Rhodium's site? Anyone know how this chem is made? Refs, patents?
What's up with the fucking chemical supply places. So far, no one is selling small amounts. >:(
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acetophenone __CH2I2__> alpha-methylstyrene
Yield 90 percent (BRN=969405)
Reagent Zn-TiCl4
Solvent tetrahydrofuran
Time 30 min
Temp 25 C
Ref: Hibino, Jun-ichi; Okazoe, Takashi; Takai, Kazuhiko; Nozaki, Hitosi; TELEAY; Tetrahedron Lett.; EN; 26; 45; 1985; 5579-5580.
CH2Cl2 __> CH2I2
Reagents acetone, NaI
Ref: Perkin; Scarborough; JCSOA9; J.Chem.Soc.; 119; 1921; 1402, 1404.
Reagents benzyl alcohol, NaI
Temp 125° C
Ref: Laskina; ZPKHAB; Zh.Prikl.Khim.(Leningrad); 32; 1959; 878, 880; engl. Ausg. S. 895, 897.
Also have a look at Post 58919 (missing)
(psyloxy: "Refs for methylenation of ketones", Chemistry Discourse) and Post 60128 (missing)
(Rhodium: "Re: found something...", Chemistry Discourse). propiophenone 2 prodine, anyone ?
--psyloxy--
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Alpha-methylstyrene (aka isopropenylbenzene) is usually bought, as it is so cheap. You need to look harder, I can find it in every catalog I have for about €15/kg.
Other than that, almost all plausible routes in the literature involves the synthesis of 2-phenyl-2-propanol as an intermediate either from methylmagnesium iodide and acetophenone or phenylmagnesium bromide and acetone, followed by dehydration of the alcohol to the alkene by heating in dilute sulfuric acid.
If you are interested in alpha-ethylstyrene, then I've posted a preparation of that from propiophenone in Post 432214 (https://www.thevespiary.org/talk/index.php?topic=9806.msg43221400#msg43221400)
(Rhodium: "Wittig Synthesis of alpha-Ethylstyrene", Methods Discourse) and a few other references in Post 363957 (https://www.thevespiary.org/talk/index.php?topic=7419.msg36395700#msg36395700)
(Rhodium: "alpha-ethylstyrene", Chemistry Discourse).
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a-Methylstyrene. This compound is not a styrenic monomer in the strict sense. The methyl substitution on the side chain, rather than the aromatic ring, moderates its reactivity in polymerization. It is used as a specialty monomer in ABS resins, coatings, polyester resins, and hot-melt adhesives. As a copolymer in ABS and polystyrene, it increases the heat-distortion resistance of the product. In coatings and resins, it moderates reaction rates and improves clarity. Physical properties of a-methylstyrene [98-83-9] are shown in Table 12.
Table 12. Physical Properties of a-Methylstyrenea
Property Value molecular weight 118.18
refractive index, n20D 1.53864
viscosity at 20°C, 0.940
surface tension at 20°C, mN/m () 32.40
density at 20°C, g/cm3 0.9106
boiling point, °C 165
freezing point, °C flash point (Cleveland open-cup), °C 57.8
fire point (Cleveland open-cup), °C 57.8
explosive limits, % in air 0.7-3.4
vapor pressure, kPab at 20°C 0.253 60°C 2.400 100°C 13.066 160°C 88.660
critical pressure, Pc, Mpac 4.36
critical temperature, tc, °C 384
critical volume, Vc, mL/g 3.26
critical density, dc, g/mL0.29
specific heat of liquid, J/()d at 40°C 2.0460 100°C 2.1757
specific heat of vapor at 25°C, J/()d 1.2357
latent heat of vaporization, DHv, J/gd at 25°C 404.55
boiling point 326.35
heat of combustion, DHc, gas at constant pressure at 25°C, kJ/mold 4863.73
heat of formation, DHf, liquid at 25°C, kJ/mold 112.97
heat of polymerization, kJ/mold 39.75
Q value 0.76 e value cubical coefficient of expansion at 20°C
solubility in H2O at 25°C 0.056 H2O in monomer at 25°C 0.010 solvent compatibilitye
Production of a-methylstyrene (AMS) from cumene by dehydrogenation was practiced commercially by Dow until 1977. It is now produced as a by-product in the production of phenol and acetone from cumene. Cumene is manufactured by alkylation of benzene with propylene. In the phenol-acetone process, cumene is oxidized in the liquid phase thermally to cumene hydroperoxide. The hydroperoxide is split into phenol and acetone by a cleavage reaction catalyzed by sulfur dioxide. Up to 2% of the cumene is converted to a-methylstyrene. Phenol and acetone are large-volume chemicals and the supply of the by-product a-methylstyrene is well in excess of its demand. Producers are forced to hydrogenate it back to cumene for recycle to the phenol-acetone plant. Estimated plant capacities of the U.S. producers of a-methylstyrene are listed in Table 13 (80).
Table 13. U.S. a-Methylstyrene Producers and Capacities, 1995 (56.000 t/y)
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J. Org. Chem. 59, 2668-70 (1994)
J. Org. Chem. 52, 4410-12 (1987)
Patent US3865848 (http://l2.espacenet.com/dips/viewer?PN=US3865848&CY=gb&LG=en&DB=EPD)
the geminal dizinc compound is metioned in the patent, IZnCH2ZnI which is the synthon intermediate for methylenation
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Alkylidenation of ester carbonyl groups by means of a reagent derived from RCHBr2, Zn, TiCl4, and TMEDA.
Takashi Okazoe, Kazuhiko Takai, Koichiro Oshima, Kiitiro Utimoto
J. Org. Chem. 52, 4410-4412 (1987) (https://www.thevespiary.org/rhodium/Rhodium/pdf/alkylidenation.ester.carbonyls.pdf)
(https://www.thevespiary.org/rhodium/Rhodium/pdf/alkylidenation.ester.carbonyls.pdf)
Summary
Reagents prepared by reduction of 1,1-dibromoalkanes (R3CHBr2) with zinc and TiCl4 in the presence of N,N,N',N'-tetramethylethylenediamine in THF are effective in the conversion of esters (R1CO2R2) to the corresponding alkenyl ethers (R1(R2O)C=CHR3) with high Z selectivity.
____ ___ __ _
A Novel Catalytic Effect of Lead on the Reduction of a Zinc Carbenoid with Zinc Metal Leading to a Geminal Dizinc Compound.
Acceleration of the Wittig-Type Olefination with the RCHX2-TiCl4-Zn Systems by Addition of Lead
Kazuhiko Takai, Tadahiro Kakiuchi, Yasutaka Kataoka, and Kiitiro Utimoto
J. Org. Chem. 59, 2668-2670 (1994) (https://www.thevespiary.org/rhodium/Rhodium/pdf/zn-carbenoid.pb-cat.pdf)
(https://www.thevespiary.org/rhodium/Rhodium/pdf/zn-carbenoid.pb-cat.pdf)
Summary
A catalytic amount of lead promotes further reduction of zinc carbenoid (ICH2ZnI) with zinc in THF to give a geminal dizinc compound (CH2(ZnI)2), which is a key intermediate for the methylenation of carbonyl compounds with a CH2I2, zinc, and TiCl4 system.
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As mentioned in
Post 58919 (missing)
(psyloxy: "Refs for methylenation of ketones", Chemistry Discourse)
and Post 461703 (https://www.thevespiary.org/talk/index.php?topic=7456.msg46170300#msg46170300)
(psyloxy: "acetophenone to alpha-methylstyrene", Chemistry Discourse)
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Carbonyl Methylenation Of Easily Enolizable Ketones
Jun-ichi Hibino, Takashi Okazoe, Kazuhiko Takai, and Hitosi Nozaki
Tet. Lett. 26(45), 5579-5580 (1985) (https://www.thevespiary.org/rhodium/Rhodium/pdf/methylenation-1.pdf)
(https://www.thevespiary.org/rhodium/Rhodium/pdf/methylenation-1.pdf)
Summary
An organometallic reagent prepared from CH2I2, Zn, and TiCl4 is effective for methylenation of the title ketones.
____ ___ __ _
Chemoselective Methylenation With A Methylenedianion Synthon
Takashi Okazoe, Jun-ichi Hibino, Kazuhiko Takai, and Hitosi Nozaki
Tet. Lett. 26(45), 5581-5584 (1985) (https://www.thevespiary.org/rhodium/Rhodium/pdf/methylenation-2.pdf)
(https://www.thevespiary.org/rhodium/Rhodium/pdf/methylenation-2.pdf)
Summary
The combination of CH2I2-Zn-Ti(i-PrO)4 or CH2I2-Zn-Me3Al is effective for the selective methylenation of aldehydes. Selective methylenation of a ketone group is performed by pretreatment of a substrate with Ti(NEt2)4.
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Pondering this how about using hydratropic aldyde as the starting material?
this can be reduced using sodium dithionite, or via catalytic tranfer hydrogenation with MgO (catalyst) and isopropanol. then the 2-phenyl-1-propanol (a chemical synonym for 2-phenyl-1-propanol is hydratropic alcohol it's CAS# is 1123-85-9) can be dehydrated using H2SO4, KHSO4, or any other method for dehydrationg alcohols to alkenes.
even simpler would be the dehydration of 2-phenyl-1-propanol itself.
This chemical is used by the fragrance industry as is hydratropic aldehyde.
The aldehyde would be easier to find.
One caveat about this is that I don't think this would work on higher substituted styrenes because the alcohol would dehydrate and the olefin would be at the more substituted carbon thus producing an internal olefin.
the advantage of this is logistical because the precursurs here are not considered as deleterious as alpha-methylstyrene as many of you know it is almost impossible to get "hazardous" chemicals unless you are industry.
according to this link it is used in food and frgrnace and has virtually no toxicity
http://www.cdc.gov/niosh/rtecs/sg8312b0.html (http://www.cdc.gov/niosh/rtecs/sg8312b0.html)
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here is a rxn for phenylcyclopropane from cinnamadehyde, using only hydrazine:
http://www.orgsyn.org/orgsyn/prep.asp?prep=cv5p0929 (http://www.orgsyn.org/orgsyn/prep.asp?prep=cv5p0929)
although i havn't figured out an exact route from here to a-methylstyrene i would be shocked if there isn't one.
perhaps catalytic rearrangment.
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I found this is easy to get too it has many synonyms cumyl alcohol, phenylethylmethanol and others.
there are foreign fragrance compnies eager to do business too
this alcohol will dehydrate using anyhydrous copper II sulfate better than the primary alcohol (hydrtropic alcohol) because it is secondary and a benzylic alcohol.
you should look into.