4- pyndine

If the temperature is not kept below 25°C dunng the reaction of primary alcohols with p toluenesulfonyl chloride in pyndine it is sometimes observed that the isolated product is not the desired alkyl p toluenesulfonate but is instead the corresponding alkyl chlonde Suggest a mech anistic explanation for this observation... 

Acridine is a heterocyclic aromatic compound obtained from coal tar that is used in the syn thesis of dyes The molecular formula of acndine is C13H9N and its ring system is analogous to that of anthracene except that one CH group has been replaced by N The two most stable reso nance structures of acridine are equivalent to each other and both contain a pyndine like struc tural unit Wnte a structural formula for acridine... 

One reason for the low reactivity of pyridine is that its nitrogen atom because it IS more electronegative than a CH in benzene causes the rr electrons to be held more tightly and raises the activation energy for attack by an electrophile Another is that the nitrogen of pyridine is protonated in sulfuric acid and the resulting pyndinium ion is even more deactivated than pyndine itself... 

Identify the more basic of the two nitrogens of 4 (N,N dimethylamino)pyndine and suggest an explanation for its enhanced basicity as compared with pyridine and N N dimethylanihne Refer to Learning By Modeling and compare your prediction to one based on the calculated charge and electrostatic potential of each nitrogen... 

Uses. 3-Pentenenitrile, 3PN, is used entirely by the manufacturers to make adiponitrile. i7j -2-Pentenenitrile, 2PN, can be cycli2ed catalyticaHy at high temperature to produce pyndine, a solvent and agncultural chemical intermediate. 2PN is also chlorinated to manufacture pentachloropyndine, an intermediate in the insecticide Dursban produced by Dow. Addition of ammonia to 2PN foUowed by reduction leads to 1,3-pentadiamine (Dytek ep), which is used as a curing agent for epoxy coatings and as a chain modifier in polyurethanes. 

Condensation of pyndine with ketones in the presence of aluminium amalgam. 

Pyrldlnlum p-toluenesulfonate (PPTS) (1). TsOH monohydrate (5 70 g, 30 mmol) was added to pyndine (12 1 mL, 1S0 mmol) with stirnng at 20 C After 20 min the excess of pyndine was removed in vacuum (60 C) Recrystallization from MeaCO gave 6 8 g of 1 (90%) mp f20 C... 

KRdHNKE - ORTOLEVA PyndiniumSalts Formation oi kelo pyndinium salts by reaction of alpha halo katona darrvatives with pyndine and th cleavage to caiboxytic acids... 

Naphtolc Acid (4). 1 and pyndine 2 were heated on a water bath for a short time The product was dissolved in ElOH and precipitated with EtjO Recrystalhzation from 10 volumes ol water affoided pure a-naphthacyl pyndinium bromide 3 A solution of 3 (0 5 g IS mmol) m waler (40 mL), EtOH (12 mL) and 10 N NaOH (2 ml) after healing for 12 min on a waler bath, gave on acidification and extraction with EtzO 4 mp 160-162°C... 

LADEN8URG Pyadlne Benzyiation Cu catalyzed a- and y-benzyiation of pyndine. 

Raagent. The yellow CrOa-pyndine reagent is prepared by adding rad CrOa at 15-20° to 10 parts of pyridine in portions with stimng. The complex is moderately soluble in pyridine and used as a suspension to whx h a 10% solution of the alcohol in pyridine is added Note if pyndine is added to CrOa the mixture usually inflamed... 

Phenylpftenanttirldlne (3).3 Amine hydrochloride 1 (2.72 g, 9 28 mmol) in EtOH (75 mL) was treated with 0 926 N cold solution of KCXI. Colorless crystals appear The mixture was shaken lor 30 mtn in ice, water was added and the product was filtered and dryed (PaOs) to afford 2.7 g of 2 (100%), rnp 102°C (hexane) 2 (2 0 g, 6 6 mmol) in anh pyndine (20 mL) was treated with an excess of NaOCHa (exothermc) Alter 20 h the solvent was removed In vacuum, the residua triturated with EtaO and the extract treated with dry HCI to obtain the hydrochlonda of 3, mp 107-108°C (from petroleum ether), mp 95-100° (Irom water) Olphenylmethyieneanlllna (5). To a suspension of lead tetraacetate (4.9 g, fO mmol) in PhH (100 mL) under Na was added a solution of tnphenyhnethylamine 4 (2 6 g, 10 mmol) in PhH (100 mL) dropwise under stirring The mixture was refluxed for 1 h, cooled, filtered, washed and the solvent evaporated The residue was crystallized from EtOH to give 2 2 g of 5 (85%), mp 111-112°C. 

Phenol (3)-2 Anisole 1 (107 g. 1 mol) and pyndine HCI 2 (130 g. 1.3 mol) were heated with AcOH (5-10 mL) for 5 h at 190 C The mixture was poured into water (500 mL) and extracted with Et20. From the EtaO solutions 3 was extracted with NaOH and the alkaline solution was saturated wHh COj. Extraction with ether and distllation of the extract afforded 94 g of 3 (100%), mp35-40 C... 

Fluorodediazoniation of alkyl carbamates in hydrogen fluonde/pyndine (70/30) represents a novel route to alkyl fluoroformates [6, 9] (equation 4)... 

This technique has been applied to the synthesis of fluormated dopamine and other compounds of biological significance Fluoroheterocycles such as fluoro-imidazoles [JJ, 36] and fluoropyrazoles [37] can also be prepared by the photo Balz-Schiemann technique (equation 9) Photochemically induced in situ fluoro dediazoniation can also be applied to arenediazonium fluorides in hydrogen fluo nde-pyndine media Thus, o-fluoroanisole is obtained in 73% yield at 20 °C after I8h [dS]... 

Nitrosyl chloride [55], nitrosyl fluoride-hydrogen fluoride liquid complexes (NOF3HF, NOF 6HF) [56], nitrous acid-hydrogen fluoride solutions [57, 5 ] nitrogen trioxide (prepared in situ from nitric oxide and oxygen) [59] and rert-butyl nitrite-hydrogen fluoride-pyndine [60] have been substituted for sodium nitrite in the diazotization step... 

Halofluonnation of a-diazoacetophenone by N halosuccmimides in hydrogen fluonde-pyndine provides good yields of a-fluoro-a-haloacetopheiiones [6] (equation 24)... 

Perfluoroalkyltin halides can be prepared via oxidative addition of perfluo-roalkyl iodides to tin(II) halides in dimethylformamide (DMF) [12] The per-fluoroalkyltin(IV) dihalide could not be isolated, but in DMF solution, the tin(lV) compound did react with aldehydes and ketones in the presence of pyndine [12] (equation 8) Typical perfluoroalkylcarbinols prepared by this method are shown in Table 1 [12]... 

Trifluoromethylzinc complexes can also be prepared by reaction of bro-motrifluoromethane with zinc in pyndine [75] (equation 26)... 

Theperfluoroorganozmc compounds have limited application in organic syn thesis because of their lack of reactivity However, heptafluoro I methylethylzinc iodide reacts with acyl fluorides or anhydrides of carboxylic acids in the presence of pyndine to give the corresponding ketones [7S] (equations 28 and 29) In the presence of zinc fluoride, acyl chlorides can be used as substrates [7d]... 

From semiamidals, the correspondmg tnfluoromethyl substituted N-acyl mines [25, 28], 1,3-diambutadienes [27], N-sulfonyl mines [5, 29], N sulfinyl mines [30], and N-phosphoryl mines [31] can be obtamed in high yields on reaction with powerful dehydratmg realms like POC -pyndine or tnfluoroacetic anhydnde-pyndme [2, 5]... 

An alkyl group can also migrate from oxygen to nitrogen or phosphorus [I, 72] (Michaelis-Arbuzov rearrangement) With this methodology, tetrafluoro-pyndine phosphonates and phosphmates can be obtained [75, 74], Chlorine fluoride... 

Tnfluoroacetic anhydride is an efficient dehydrating reagent [46, 47] In the presence of pyndine, it smoothly dehydrates amides and aldoximes to the correspond ing nitriles [46] and adducts of CH-acids and 1,2,3-indantnone [47] (equation 20)... 

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