1.3- dibromo propane

This is incorrect There is no reason to believe that the second bromine will be introduced exclusively at C-l. In fact, the selectivity rules for bromination tell us that 2,2-dibromo-propane is the expected major product. 

Electrochemical cyclopropanation of alkenes occurs using dibromomethanes at a sacrificial zinc electrode in a CH2C12/DMF mixture with a one compartment cell (equation 65). Yields using more than twenty isolated and conjugated olefins were generally good (30 to 70%)98. Benzal halides give only poor yields in the same reaction, but 2,2-dibromo-propane leads to the equivalent gem-dimethylcyclopropanes in fair yields. The method represents a useful alternative to other methods of cyclopropanation of olefins such as the Simmons-Smith reaction. 

Geminal (Section 19.5) Referring to two groups attached to the same carbon atom. For example, 1,1-dibromo-propane is a geminal dibromide. 

An interesting rearrangement of thioureas leading to tetrahydro-1,3-thiazines has been reported by Tisler,297,298 who found that 1-trimethylene-3-aryl-2-thioureas undergo facile conversion to 150 in concentrated HC1. The same products (150) could also be prepared by treating the appropriately substituted thiourea with 1,3-dibromo-propane.298... 

Trimethyl-3,4,6,7,8,9-hexahydro-2//-pyrido[2,l-h][l,3]oxazonium salt was prepared in the reaction of lithio salt (173) and 1,3-dibromo-propane inTHF at room temperature (73JOC36). 

Reactions of 3-hydroxy-6-methyl-2(lfl)-pyridinethione with 1,3-dibromo-propanes in methanol in the presence of sodium methylate yielded betaines (205) (70ACS2949). 9-Hydroxy-3,4-dihydro-2f/-pyrido[2,l-6][1,3]-thiazinium bromide was obtained in the reaction of 3-hydroxypyridine-2(lH)-thione and l-bromo-3-chloropropane in boiling toluene [81JCR(S)208]. 

Tetrahydro[l,3]thiazino[2,3-a]isoquinolin-6-ones (215) were prepared in the reactions of 3-hydroxy-1-mercaptoisoquinoline with 1,3-dibromo-propane and l,3-dibromopropan-2-ol in methanolic sodium methylate at 50°C (72ACS1620). 

Preparation 323.—Cinnamic Acid Dibromide Z-Phenyl-2 3-dibromo-propan acid. ... 

Alkylation of chiral MofNOblSjCf.fLh 2 with racemic 1,2-dibromo-propane or 1,2-dibromobutane gives diastereospecifically the pair of [Mo(NO)2(RS4)] enantiomers with equatorial R substituents (Eq. 17) (20). (This pair is one out of four theoretically possible pairs of diaster-eomeric enantiomers.)... 

BrCH2CH2CH2Mn(CO)5 is formed by reaction of [Mn(CO)5] with 1,3-dibromo-propane. However, the reaction does not stop here the product reacts with additional [Mn(CO)5l to yield a carbene complex. Propose a structure for this complex and suggest a mechanism for its formation. 

Selenetane is a pungent liquid obtained in low yield by treating 1,3-dibromo-propane with sodium selenide. Substituted selenetanes have been obtained by treatment of 1,3-dihalopropanes (e.g., 644) with potassium selenide or the cyclic monocarbonate of pentaerythritol with potassium selenocyanate. 3-Hydroxyselenetane 645 [ H nmr 5 3.6 (7=5.8) (H ) 3.85 (OH), 3.9-4.2(m) (H )ppm] is obtained by electrolysis in a diaphragm cell of chloromethyloxirane (epichlorohydrin) in the presence of selenium powder. It is also obtained by treatment of l,3-dibromo-2-propanol with NaSeH. Tetravalent, four-membered selenuranes are formed by treatment of 3,3-dimethylselentane with bromine at low temperature, and by treatment of the 1,1-dibromoselenetane... 

Benzo[c]cinnoline is a weak base with a of 2.2 in water and 1.6 in 50% aqueous ethanol.Cryoscopic measurements show that it is dipro-tonated to some extent in 100% sulfuric acid. Well-defined quaternary salts result from heating benzo[c]cinnoline with alkyl halides and sul-fates. These are reported to decompose on treatment with ammonia, regenerating benzo[c]cinnoline, but apparently nucleophilic displacements of halogen by amines have been carried out on certain highly substituted examples in the synthesis of cationic dyestuffs. Quaternizations of benzo[c]cinnoline with a,a)-dibromo-propane and -butane are accompanied by hydrogen bromide elimination to give the cyclic iminium salts 40 and 41. When 40 is dehydrogenated, or merely refluxed in ethanol. 

Perhydro-l,3-thiazine-2-thiones (211) can be synthesized from thioureas and 1,3-dibromo-propanes in the presence of sodium hydroxide, followed by the treatment of the product imines... 

In a complementary process, the reaction of active methylene compounds, and derivatives such as the enamine shown, with ditosylated 1,3-dithiols, derived from the reaction of 1,3-dibromo-propane with potassium thiotosylate, can provide unusually substituted 1,3-dithianes (Equation... 

Cyclopropane. Trimethylene. C H( mol wt 42,08. C 85.63%, H 14.37%. Prepd by reduction of 1,2-dibromo-cyclopropane with zinc and alcohol Lott, Christiansen, J. Am. Pharm. Assoc. 19, 341 (1930) Schlatter, J. Am. Chem. Soc. 63, 1733 (1941) from 1,3-dibromopropane with zinc and alcohol in absence of water Ashdown et at, ibid. 58, 850 (1936) by the action of sodium vapor on 1,3-dibromo-propane Bawn, Hunter, Trans Faraday Soc. 34, 608 (1938) from 1,3-dichloropropane heated with an excess of zinc dust, iodine and ethanol in 80% yield Hass el at, Ind. Eng. Chem. 28, 1178 (1936) from 1,3-dichloropropane with zinc in presence of sodium iodide U.S. pat. 2,102 556 (1937) cf. 

In 1925 Spath and Roller described a new ephedrine synthesis. a-Phenylpropylene was reacted with bromine to l-phenyl-l,2-dibromo-propane. One bromine was then substituted by methoxyl, the other by NH CHa. On hydrolysis with fuming hydrobromic acid, racemic -ephedrine was formed. (Compare also Spath and Bretschneider, 261.)... 

The cyclic alkylation of l,2-phenylenebis(phosphine) in the complex (152) with 1,3-dibromo-propane under basic conditions gives a variety of phosphines after the displacement from the metal, including the bis(secondary phosphine) (153) and the R, S diastereomers of the bis(tertiary phosphines) (154) and (155) the crystal structure was determined of the square-planar complex unt/-[Ni (/, 5 )-(154) 2KCI04)2-CH2Cl2 <95MI 934-0l>. 

Displayed here is a representative reaction between diethyl malonate and 1,3-dibromo-propane in absolute EtOH, using NaOEt as the base. 

VISCOSITY DEPENDENCE OF RELAXATION TIMES OF 1,3-DIBROMO-PROPANE AND 1,4-DIBROMOBUTANE. 

Whereas photosensitized bromination of cyclopropane affords 1,3-dibromo-propane, bromination with NBS gives cyclopropyl bromide. Thus, whereas Br reacts exclusively by attack on carbon to give ring-opening, the succinimidyl radical abstracts hydrogen to give a cycloprop radical, which rapidly combines with a bromine atom. ... 

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