590-19-2

Basic information

• Product Name: 1,2-Butadiene
• Synonyms: 1-Methylallene;Allene, methyl-;Butadiene-1,2;Methylallene
• CAS NO: 590-19-2
• Molecular Formula: C₄H₆
• Molecular Weight: 54.10
• EINECS: 209-674-2
• Mol File: 590-19-2.mol
• Article Data: 29

Chemical Properties

• Boiling Point: 10.7 °C at 760 mmHg
• Appearance: colorless gas
• Density: 0.612 g/cm³
• CAS DataBase Reference: 1,2-Butadiene(CAS DataBase Reference)
• NIST Chemistry Reference: 1,2-Butadiene(590-19-2)
• EPA Substance Registry System: 1,2-Butadiene(590-19-2)

Safety Data

• Hazardous Substances Data: 590-19-2(Hazardous Substances Data)

Usage

General Description

1,2-Butadiene, also known as butadiene, is a colorless, flammable gas with a mild gasoline-like odor. It is a highly reactive chemical compound that is widely used in the production of synthetic rubber, particularly in the manufacturing of tires. 1,2-Butadiene is also used in the production of plastics, resins, and other chemicals. Exposure to 1,2-butadiene can occur through inhalation, ingestion, or skin contact, with potential health effects including irritation of the eyes, nose, and throat, as well as adverse effects on the nervous system, kidneys, and cardiovascular system. Due to its classification as a potential human carcinogen, occupational exposure to 1,2-butadiene is closely regulated in many countries to minimize health risks to workers in industries where it is used.

InChI:InChI=1/C4H6/c1-3-4-2/h4H,1H2,2H3

Synthetic route

3-methylpent-4-yn-2-ol (41998-65-6) → 2,3-dimethylbutene (590-19-2)

Conditions	Yield
at 660℃; under 0.001 Torr;	98%

Methylcyclopropen (3100-04-7) → dimethylacetylene (503-17-3) + 2,3-dimethylbutene (590-19-2) + buta-1,3-diene (106-99-0)

Conditions	Yield
With sulphur hexafluoride at 230.2℃; under 20.5 Torr; for 1.5h; Product distribution; Rate constant; Kinetics; var. time, var. pressure;	A 91.31% B 1.84% C 6.85%
Product distribution; Quantum yield; Irradiation;
In gas under 0.1 - 6 Torr; Mechanism; Product distribution; Irradiation;

3-chloro-but-1-yne (21020-24-6) → 2,3-dimethylbutene (590-19-2)

Conditions	Yield
	61%

2-propynyl chloride (624-65-7) + dimethyldiazene → but-1-yne (107-00-6) + 2,3-dimethylbutene (590-19-2)

Conditions	Yield
at 20℃; under 50 Torr; Kinetics; radical cross-combination reaction; Photolysis;	A 60% B 40%

3-buten-1-yne (689-97-4) → 2,3-dimethylbutene (590-19-2)

Conditions	Yield
With iron at 23 - 110℃; under 29420.3 Torr; Hydrogenation.in Gegenwart eines Polymerisationsinhibitors;

but-1-yne (107-00-6) → 2,3-dimethylbutene (590-19-2)

Conditions	Yield
With cefaloridine at 280℃;
Cs-exchanged H(x)Cs30Na19(AlO2)54(SiO2)138 zeolite Ambient temperature;

but-1-yne (107-00-6) → 2,3-dimethylbutene (590-19-2) + buta-1,3-diene (106-99-0)

Conditions	Yield
at 275℃; Leiten ueber Floridin;

dimethylacetylene (503-17-3) + cefaloridine (50-59-9) → but-1-yne (107-00-6) + 2,3-dimethylbutene (590-19-2)

Conditions	Yield
at 280℃;

dimethylacetylene (503-17-3) → 2,3-dimethylbutene (590-19-2)

Conditions	Yield
With cefaloridine at 280℃;

2-methyl-but-2-ene (513-35-9) → propene (187737-37-7) + ethene (74-85-1) + 2,3-dimethylbutene (590-19-2) + isoprene (78-79-5)

Conditions	Yield
at 750℃; under 15 Torr;

2-methyl-but-2-ene (513-35-9) → naphthalene (91-20-3) + ethene (74-85-1) + 2,3-dimethylbutene (590-19-2) + benzene (71-43-2)

Conditions	Yield
at 750℃; Produkt 5:Anthracen;

biphenyl (92-52-4) → 2,3-dimethylbutene (590-19-2) + benzene (71-43-2)

Conditions	Yield
at 1300 - 1500℃; Pyrolysis;

methylene (2465-56-7) + dibutyl ether (142-96-1) → butyl methyl ether (628-28-4) + 2,3-dimethylbutene (590-19-2) + n-butyl n-pentyl ether (18636-66-3)

2,3-dibromo-but-1-ene (52111-97-4) → 2,3-dimethylbutene (590-19-2)

Conditions	Yield
With ethanol; zinc

phosphoric acid tributyl ester (126-73-8) → 2,3-dimethylbutene (590-19-2)

Conditions	Yield
at 500℃; Pyrolysis;

ethanol (64-17-5) → 2,3-dimethylbutene (590-19-2) + acetaldehyde (75-07-0)

Conditions	Yield
Mechanism;

iso-butanol (78-92-2, 15892-23-6) → Ketene (463-51-4) + 2,3-dimethylbutene (590-19-2) + acetone (67-64-1)

Conditions	Yield
at 600℃;

propane (74-98-6) → propene (187737-37-7) + methane (34557-54-5) + ethene (74-85-1) + 2,3-dimethylbutene (590-19-2)

Conditions	Yield
at 700 - 1000℃; bei der termischen Zersetzung; Produkt 5: Benzol; Produkt 6: Acetylen; Produkt 7: Kohlenstoff; Produkt 8: Wasserstoff;

1,2,2,3-tetrachloro-butane (79630-70-9) → 2,3-dimethylbutene (590-19-2)

Conditions	Yield
With zinc copper; ethanol

1,2-dibromo-2-butene (20629-39-4, 20629-62-3, 79629-38-2) → 2,3-dimethylbutene (590-19-2)

Conditions	Yield
With ethanol; zinc

ethanol (64-17-5) + acetaldehyde (75-07-0) → 2,3-dimethylbutene (590-19-2)

Conditions	Yield
With aluminum oxide at 360 - 460℃;

n-butane (106-97-8) → butene-2 (107-01-7) + 2,3-dimethylbutene (590-19-2)

Conditions	Yield
nach dem Houdry-Prozess;

butan-1-ol (71-36-3) → 2,3-dimethylbutene (590-19-2)

Conditions	Yield
at 600℃;

2-pentene (109-68-2) → penta-1,3-diene (504-60-9) + 2,3-dimethylbutene (590-19-2)

Conditions	Yield
at 800℃; under 147.1 Torr; bei Verduennung mit Stickstoff und Kontaktzeit von 0.07 sec;

2-pentene (109-68-2) → penta-2,3-diene (591-96-8) + 2,3-dimethylbutene (590-19-2)

Conditions	Yield
at 760 - 833℃; bei Verduennung mit Wasserdampf und einer Kontaktzeit von 0.005-0.1 sec;

2-pentene (109-68-2) → 2,3-dimethylbutene (590-19-2)

Conditions	Yield
at 650℃; bei Verduennung mit Wasserdampf und Kontaktzeit von 0.4-1 sec;

C18H16 → 2,3-dimethylbutene (590-19-2)

Conditions	Yield
at 750℃; under 0.001 Torr;

but-1-yne (107-00-6) → dimethylacetylene (503-17-3) + 2,3-dimethylbutene (590-19-2)

Conditions	Yield
tetrahydrofuran; samarium at 79.9℃;

but-1-yne (107-00-6) → dimethylacetylene (503-17-3) + 2,3-dimethylbutene (590-19-2) + buta-1,3-diene (106-99-0)

Conditions	Yield
calcium oxide at 30℃; Product distribution;

dimethylacetylene (503-17-3) → 1-butylene (106-98-9) + (Z)-2-Butene (590-18-1) + 2,3-dimethylbutene (590-19-2)

Conditions	Yield
With hydrogen; tetrahydrofuran; samarium variation of rare earth catalyst, selectivity;
With hydrogen; tetrahydrofuran; samarium at 79.9℃;

2,3-dimethylbutene (590-19-2) + 2-(methyldiphenylsilyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (200010-86-2) → (S)-3-(diphenylmethylsilyl)-2-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1-butene

Conditions	Yield
With catalyst:Pd(dba)2/R-1,1'-bina-2yl-P(3,5C6H3-Me2)2 In toluene 0°C, 22-90 h, bis(dibenzylideneacetone) palladium / (R)-(1,1')binaphthalenyl-2-yl-bis-(3,5-dimethyl-phenyl)-phosphane as catalyst;	96%

2,3-dimethylbutene (590-19-2) + [IrRu(CO)4(μ-CH2)(bis(diphenylphosphino)methane)2][BF4] → [IrRu(CO)4(κ1:κ1-MeCH=CCH2CH2)(bis(diphenylphosphino)methane)2][BF4]

Conditions	Yield
In dichloromethane (Ar, Schlenk) methylallene was passed through a stirred soln. of complexin CH2Cl2 for 1 min at a rate 0.1 mL/s, stirred under methylallene atm. at ambient temp. for 24 h; reduced in vol., diethyl ether was added, ppt. was washed with diethyl ether (twice) and dried in vac.; elem. anal.;	94%

2,3-dimethylbutene (590-19-2) + (1R,2R,6S,8R)-4-(Dimethyl-phenyl-silanyl)-2,9,9-trimethyl-3,5-dioxa-4-bora-tricyclo[6.1.1.02,6]decane (612835-98-0) → (C6H7(C(CH3)2)(CH3)O2)BC(CH2)CH(Si(CH3)2C6H5)CH3

Conditions	Yield
With (C5H5)(allyl)Pd; (R)-Ph2PC10H6C10H7 In toluene allene (1.2 equiv.) added to mixt. of P ligand and Pd compd. in toluene at room temp.; (R)-silylborane added; mixt. stirred at room temp. for 8-24 h; bulb-to-bulb distd. under vac.; ratio of (R,S) to (R,R) = 93:7;	92%

(η5-C5H5)(Me)(NO)(PPh3)rhenium(II) + 2,3-dimethylbutene (590-19-2) → (C5H5)Re(NO)(P(C6H5)3)(H2CCCHCH3)(1+)*BF4(1-)={(C5H5)Re(NO)(P(C6H5)3)(H2CCCHCH3)}{BF4}

Conditions	Yield
With HBF4*Et2O In chlorobenzene under inert gas; addn. of HBF4*OEt2 to a soln of (C5H5)Re(NO)(PPh3)(CH3) at -45°C with stirring, after 30 min addn. of 1,2-butadiene, stirring at room temp. for 5 d;; evapn., pptn., filtration, dissolving (CH2Cl2), addn. to hexane, pptn., crystn. (CH2Cl2/ether); elem. anal.;	90%

bis(1,5-cyclooctadiene)nickel (0) (1295-35-8) + 2,3-dimethylbutene (590-19-2) → ((C5H4N)2)Ni(CH2C(CHCH3)COO)

Conditions	Yield
With [2,2]bipyridinyl; carbon dioxide In tetrahydrofuran MeCH=C=CH2 was added at -78°C to a suspn. of (COD)2Ni and bipy in THF, reaction vessel was evacuated, CO2 admitted at -78°C, mixt. was warmed at 20°C and stirred for 48 h; soln. was concd. in vacuo, pentane added, ppt. was filtered off, washedwith pentane and dried in vacuo; elem. anal.;	88.5%

2,3-dimethylbutene (590-19-2) + 1,2-dimethoxy-1,1,2,2-tetramethyldisilane (10124-62-6) → 2,3-bis(dimethylmethoxysilyl)but-1-ene

Conditions	Yield
With butene-2; tetrakis(triphenylphosphine) palladium(0) at 120℃; for 15h;	88%
With tetrakis(triphenylphosphine) palladium(0) In benzene at 120℃; for 15h;	88%

2,3-dimethylbutene (590-19-2) + dimethylphenyl(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)silane (185990-03-8) → 2-[2-(Dimethyl-phenyl-silanyl)-1-methylene-propyl]-4,4,5,5-tetramethyl-[1,3,2]dioxaborolane

Conditions	Yield
With ethriol phosphite; tris(dibenzylideneacetone)dipalladium (0) In tetrahydrofuran at 80℃; for 9h; Addition;	88%
With catalyst: Pd2(dba)3 + etpo In tetrahydrofuran heating catalyst at 80°C for 5 min, addn. of diene and B-compound, heating at 80°C for 9 h; TLC;	88%

2,3-dimethylbutene (590-19-2) + acetophenone (98-86-2) → (3R,4R)-4-hydroxy-3-methyl-4-phenylpentan-2-one + (S,S)-4-hydroxy-3-methyl-4-phenylpentan-2-one

Conditions	Yield
Stage #1: 2,3-dimethylbutene; acetophenone With (R)-Cl-MeO-BiPhep; bis(pinacol)diborane; copper(l) chloride; sodium t-butanolate In tetrahydrofuran at 22℃; for 18h; Inert atmosphere; Stage #2: With sodium perborate In tetrahydrofuran; water at 22℃; for 1h; Inert atmosphere; enantioselective reaction;	A n/a B 88%

2,3-dimethylbutene (590-19-2) + methoxypentamethyldisilane (18107-29-4) → 3-(Methoxy-dimethyl-silanyl)-2-trimethylsilanyl-but-1-ene

Conditions	Yield
With tetrakis(triphenylphosphine) palladium(0) In benzene at 120℃; for 15h;	87%

2,3-dimethylbutene (590-19-2) + acetophenone (98-86-2) → (S,S)-4-hydroxy-3-methyl-4-phenylpentan-2-one

Conditions	Yield
Stage #1: 2,3-dimethylbutene; acetophenone With 2,2'-bis-(diphenylphosphino)-1,1'-binaphthyl; bis(pinacol)diborane; copper(l) chloride; sodium t-butanolate In tetrahydrofuran at 22℃; for 18h; Inert atmosphere; Stage #2: With sodium perborate In tetrahydrofuran; water at 22℃; for 1h; Inert atmosphere; diastereoselective reaction;	87%

2,3-dimethylbutene (590-19-2) + 1,1,2,2-tetramethoxy-1,2-dimethyl-disilane (18107-32-9) → 2,3-Bis-(dimethoxy-methyl-silanyl)-but-1-ene

Conditions	Yield
With tetrakis(triphenylphosphine) palladium(0) In benzene at 120℃; for 15h;	86%

[RhOs(CO)4(μ-CH2)(dppm)2][BF4] + 2,3-dimethylbutene (590-19-2) → [RhOs(CO)2(μ-η3:η1-CH(CH3)C(CH2)2)(dppm)2][BF4]

Conditions	Yield
With trimethylamine oxide In dichloromethane byproducts: CO; (Ar); passing methylallene through a soln. of cluster in CH2Cl2, addn. of amine oxide, stirring for 30 min; filtration, addn. of pentane, washing ppt. with ether, drying in argon; elem. anal.;	86%

2,3-dimethylbutene (590-19-2) + [IrOs(CO)4(μ-Ph2PCH2PPh2)2][BF4] → [IrOs(CO)3(μ-η3:κ1-CH2CCHCH3)(μ-Ph2PCH2PPh2)2][BF4] (1380397-20-5)

Conditions	Yield
In dichloromethane byproducts: CO; (Ar); CH3CHCCH2 passed through a soln. of Ir complex for 1 min, stirred under CH3CHCCH2 for 4 h at ambient temp.; concd., pptd. (Et2O), washed (Et2O), dried (vac.); elem. anal.;	85%
With (CH3)3NO In not given (Ar);

2,3-dimethylbutene (590-19-2) + 1,1,2-trichloro-1,2,2-trimethyldisilane (13528-88-6) → 2,3-Bis-(dichloro-methyl-silanyl)-but-1-ene

Conditions	Yield
With tetrakis(triphenylphosphine) palladium(0) In 1,3,5-trimethyl-benzene at 100℃; for 5h;	84%

2,3-dimethylbutene (590-19-2) + 1,1,2,2-tetrachloro-1,2-dimethyldisilane (4518-98-3) → 2,3-Bis-(dichloro-methyl-silanyl)-but-1-ene

Conditions	Yield
With butene-2; tetrakis(triphenylphosphine) palladium(0) at 100℃; for 5h;	84%

2,3-dimethylbutene (590-19-2) + n-C8H17X → 3-methyl-undeca-1,2-diene (59409-51-7) + 2,3-dodecadiene (56956-47-9) + 3-methylundec-1-yne (77764-66-0)

Conditions	Yield
With n-butyllithium In tetrahydrofuran; hexane -78 deg C, 30 min -> room temperature;	A 15% B 84% C 1%

2,3-dimethylbutene (590-19-2) + 4-nitrobenzaldehdye (555-16-8) → 1-(4-nitrophenyl)-2-methylbut-3-en-1-ol

Conditions	Yield
With isopropyl alcohol; caesium carbonate In ethyl acetate; 1,2-dichloro-ethane at 75℃; for 14h;	83%

Pt(2+)*CH3(1-)*C8H12={PtCH3(C8H12)}(1+) + 2,3-dimethylbutene (590-19-2) + hydrotris(1H-pyrazol-1-yl)borate(1-) → {HB(C3H3N2)3}(1-)*Pt(2+)*CH3CHCCH2*CH3(1-)={HB(C3H3N2)3}Pt(CH3)(CH3CHCCH2)

Conditions	Yield
In not given in react. of (HB(pz)3)(1-) with the solvated cation (Pt(CH3)(COD))(1+) an insol. and probably polymeric product is formed; this reacts readily with substituted allene;;	83%
In not given in react. of (HB(pz)3)(1-) with the solvated cation (Pt(CH3)(COD))(1+) an insol. and probably polymeric product is formed; this reacts readily with substituted allene;;	83%

4-nitrobenzyl chloride (619-73-8) + 2,3-dimethylbutene (590-19-2) → 1-(4-nitrophenyl)-2-methylbut-3-en-1-ol

Conditions	Yield
caesium carbonate In ethyl acetate; 1,2-dichloro-ethane at 75℃; for 14h;	82%

2,3-dimethylbutene (590-19-2) + cyclohexane carbonitrile (766-05-2) + bis(pinacol)diborane (73183-34-3) → C17H32BNO2

Conditions	Yield
Stage #1: 2,3-dimethylbutene; cyclohexane carbonitrile; bis(pinacol)diborane With (2R)-1-[(1R)-1-[bis(1,1-dimethylethyl)phosphino]ethyl]-2-(diphenylphosphino)ferrocene; mesitylcopper(I) In methanol; diethyl ether at -40℃; for 10h; Stage #2: With aluminium(III) triflate In methanol for 2h; Stage #3: With methanol; lithium borohydride at -78℃; for 4h; stereoselective reaction;	81%

[Ni(1,5,9-cyclododecatriene)] (548757-70-6, 33154-75-5, 12126-69-1, 548757-71-7, 39330-67-1) + 2,3-dimethylbutene (590-19-2) + 1,2-bis-(dicyclohexylphosphino)ethane (23743-26-2) → ((C6H11)2PCH2CH2P(C6H11)2)Ni(CH2C(CHCH3)COO)

Conditions	Yield
With carbon dioxide In tetrahydrofuran MeCH=C=CH2 was added at -78°C to a suspn. of (CDT)Ni and diphosphine in THF, reaction vessel was evacuated, CO2 admitted at -78°C, mixt. was warmed at 20°C and stirred for 48 h; soln. was concd. in vacuo, pentane added, ppt. was filtered off, washedwith pentane and dried in vacuo; elem. anal.;	80.2%

2,3-dimethylbutene (590-19-2) + dimethyl acetylenedicarboxylate (762-42-5) → 1,2,3,4-Tetrakis(carbomethoxy)-5-ethyl-benzol

Conditions	Yield
With <2,6-(ipr)2-C6H3-N=CH-CH=N-2,6-(ipr)2C6H3>Pd-(COOMe)4-cyclopentadiene In toluene at 40℃; for 48h;	80%

2,3-dimethylbutene (590-19-2) + [IrRu(CO)4(bis(diphenylphosphino)methane)2][BF4] (323185-93-9) → [IrRu(CO)4(μ-C=C(H)CH2CH3)(μ-Ph2PCH2PPh2)2][BF4]2

Conditions	Yield
In dichloromethane (N2); Schlenk technique; stirred soln. of Ir-Ru complex in CH2Cl2 was satd. with methylallene; stirred at ambient temp. for 24 h; pentane added; filtered; rinsed (pentane); dried (vac.);	80%

2,3-dimethylbutene (590-19-2) + 4-methoxy-benzaldehyde (123-11-5) → 1-(4-methoxyphenyl)-2-methylbut-3-en-1-ol

Conditions	Yield
With isopropyl alcohol; caesium carbonate In ethyl acetate; 1,2-dichloro-ethane at 75℃; for 14h;	79%

2,3-dimethylbutene (590-19-2) + methyl 3,3,3-trifluoropyruvate (13089-11-7) → methyl 2-hydroxy-2-trifluoromethylhex-4-ynoate

Conditions	Yield
at 100℃; for 24h;	78%

2,3-dimethylbutene (590-19-2) + 1-phenylethan-1-iminium chloride (107836-65-7) + bis(pinacol)diborane (73183-34-3) → C18H28BNO2

Conditions	Yield
With C57H66N2O3S; copper(l) chloride; sodium t-butanolate In tetrahydrofuran at 22℃; for 24h; stereoselective reaction;	78%

2,3-dimethylbutene (590-19-2) + benzaldehyde (100-52-7) → 2-methyl-1-phenyl-3-butene-1-ol (25201-44-9)

Conditions	Yield
With isopropyl alcohol; caesium carbonate In ethyl acetate; 1,2-dichloro-ethane at 75℃; for 14h;	77%

2,3-dimethylbutene (590-19-2) + bis(pinacol)diborane (73183-34-3) → (R)-4,4,5,5-tetramethyl-2-(3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)but-1-en-2-yl)-1,3,2-dioxaborolane

Conditions	Yield
With tris-(dibenzylideneacetone)dipalladium(0) In toluene room temp., 14 h; chromy. on silica;	77%
With tris-(dibenzylideneacetone)dipalladium(0) In toluene room temp., 14 h; chromy. on silica;	68%

Upstream product

• 689-97-4 3-buten-1-yne 
• 107-00-6 but-1-yne 
• 503-17-3 dimethylacetylene 
• 50-59-9 cefaloridine 
• 513-35-9 2-methyl-but-2-ene 
• 92-52-4 biphenyl 
• 2465-56-7 methylene 
• 142-96-1 dibutyl ether 
• 52111-97-4 2,3-dibromo-but-1-ene 
• 126-73-8 phosphoric acid tributyl ester 
• 64-17-5 ethanol 
• 78-92-2 iso-butanol 
• 74-98-6 propane 
• 79630-70-9 1,2,2,3-tetrachloro-butane 

Downstream Products

• 85-43-8 1,2,3,6-Tetrahydrophthalic anhydride 
• 4994-16-5 4-phenylcyclohexene 
• 19689-18-0 4-decene 
• 504-60-9 penta-1,3-diene 
• 100-70-9 2-Cyanopyridine 
• 28016-65-1 triphenyl-(5,5,5-triphenyl-pent-2t-enyl)-boric acid ; tetramethylammonium salt 
• 54705-48-5 1,4-dibenzoyl-2-vinyl-1,2,3,4-tetrahydro-quinoxaline 
• 107-00-6 but-1-yne 
• 106-99-0 buta-1,3-diene 
• 106-98-9 1-butylene 
• 107-01-7 butene-2 
• 503-17-3 dimethylacetylene 
• 497-06-3 3,4-butenediol 
• 52111-97-4 2,3-dibromo-but-1-ene 

Relevant articles and documents

The 213.8-nm Photochemistry of Gaseous 1,3-Butadiene and the Structure of Some C3H3 Radicals

A systematic study of the 213.8-nm (zinc line ) photochemistry of 1,3-butadiene has been made either in the absence or in the presence of various additives - such as radical scavengers (O2,NO,DI) and collisional quenchers - in the gas phase (pressure between 1 and 500 Torr).The major fate of the photoexcited 1,3-butadiene molecule is isomerization to the 1,2-butadiene structure which may then decompose to methyl and C3H3 radicals (Φ = 0.64 +/- 0.04 at 1 Torr of 1,3-butadiene).Minor processes include decomposition to the acetylene + ethylene couple (Φ = 0.22 +/- 0.02) or to vinylacetylene (Φ = 0.038 +/- 0.003) and molecular hydrogen.These two minor processes occur from different excited states.Some 2-butyne (Φ / = 10, the highest ratio used, Φ(allene + propyne)/ Φ(CH3D) = 0.72 and a fraction of the C3H3 radicals are still not accounted for (reaction with 1,3-butadiene and/or recombination ?).The relative energies obtained by ab initio RHF-SCF geometry optimizations for the doublet electronic state of the C3H3 radical structures are E(propargyl) 2B1 state) is the lowest energy one.There are probably at least two distinct C3H3 radical structures (different states) present in the far-UV photolysis of 1,3-butadiene.

Metal ions do not play a direct role in the formation of carbon-carbon triple bonds during reduction of trihaloalkyls by CrII or V II

Carbyne radicals: Reactions of trihaloalkyl compounds with Cr2+ or V2+ in aqueous solutions yield alkynes and other products. Stepwise halogen abstractions from the trihaloalkyls form alkyl carbyne triradicals in solution. These radicals undergo coupling reactions, producing triply bonded alkyne molecules (see scheme). This process is not metal-assisted and does not occur in the coordination sphere of the metal ions.

Nucleophilic reactivity of 1-zirconacyclopent-3-ynes: Carbon-carbon bond formation with aldehydes

Nucleophilic reactions of 1,1-bis(η5-cyclopentadienyl)-1-zirconacyclopent-3-yne (1) with proton and aldehydes were studied. The reaction with HCl gave a mixture of 2-butyne and 1,2-butadiene. Complex 1 reacted with benzaldehyde to give 1-phenyl-2-methyl-2,3-butadien-1-ol (3) in moderate yields in the presence of a proton source such as triethylammonium hydrochloride, while it gave 2-methylene-1-phenyl-3-buten-1-ol (4) on using triethylammonium tetraphenylborate.