Benzoe resin

Benzoe resin (also known as benzoin) comes from Styrax spp. (Styraceae family). In the Sty rax genus the only species that occurs in the Mediterranean is Styrax officinalis, so this was probably the source of the resin in ancient times in that area. Benzoe mainly contains free cinnamic and benzoic acids, and their corresponding esters with cinnamyl, p-coumaryl and coniferyl alcohols. The amounts of these compounds are quite variable and depend on which species the resin was obtained from [129]. 

GC/MS has provided the first chemical evidence of the presence of benzoe resin in an archaeological material from the Mediterranean area [18]. The procedure was... 

Figure 8.13 Total ion current chromatogram of the acidic fraction of the sample collected from the Roman Egyptian censer showing the presence of benzoe resin. ISlr internal standard, hexadecane IS2, internal standard, tridecanoic acid...

C9H12O, Mr 136.19, bpmkP 237.5 °C, df 1.008, nf 1.5278, occurs both in free and esterified form in resins and balsams (e.g., benzoe resin and Peru balsam). It has been identified in fruit and ciimamon. 

Benzo-(a)-pyrldo- 4,3,h>-ecrldlne (3). To e mixture of S-amuKiisoquinolins 1 (1 5 g, 11 mmol) and p-naphlol 2 (1 5 g, 10 mmol) hesled lo 250°C, was added in small portions paraformaldehyde (0.4S g, ISO mmol) when stesm had ceased lo evolve, the mixture was healed tor a lew more minutes then fractionated in vacuum. The thick resin (bp 200°C-11 mm) was collected arxJ recrystelllized from BuOH. A final purificalion was effected by vecuum sublimation lo afford 1.3 g of 3 (46%), mp 289°C. 

A Friedel-Crafts-type reaction of phenols under basic conditions is also possible. Aqueous alkaline phenol-aldehyde condensation is the reaction for generating phenol-formaldehyde resin.34 The condensation of phenol with glyoxylic acid in alkaline solution by using aqueous glyoxylic acid generates 4-hydroxyphenylacetic acid. The use of tetraalkylammonium hydroxide instead of sodium hydroxide increases the para-selectivity of the condensation.35 Base-catalyzed formation of benzo[b]furano[60]- and -[70]fullerenes occurred via the reaction of C60CI6 with phenol in the presence of aqueous KOH and under nitrogen.36... 

Figure 43 The cross-linking reaction of the boron-containing Novolac resin (66) (obtained by the modification of the commercially available Novolac resin) with bis(benzo-l,3,2-dioxaborolanyl)oxide. (Adapted from ref. 91.)...

Natural resins Pine resins, sandarac, copals, mastic, dammar, amber, frankincense, benzoe, styrax, myrrh, (plant resins) shellac (animal resin) tar and pitch (from thermal treatment of plant resins or wood) Varnishes, coatings, waterproofing materials, paint binders, ingredients of cosmetic and pharmaceutical preparations... 

Phenolic resins are mainly composed of aromatic esters benzoe and storax were the most common in the Mediterranean [86]. 

Quinazolines, the benzo derivatives of pyrimidines, were prepared in a variety of ways, from methods analogous to those for synthesizing pyrimidines to vastly different condensation schemes. In analogous fashion to many pyrimidine preparations, Yang and coworkers reported the condensation of polymer-tethered amidines 109 with cyclic anhydrides 110 to yield a library of 2-amino-4(3//)-quinazoIinones 111 after cleavage from the resin <00TL7005>. 

The steam-volatility of isomeric thienothiophenes allows separation from the resinous products formed during their synthesis from citric acid or acetylene. Selenophenoselenophenes are also steam-volatile. It is, however, very difficult to separate the isomeric thienothiophenes from each other and from benzo[b]thiophene with which they are also... 

The Pechmann and Knoevenagel reactions have been widely used to synthesise coumarins and developments in both have been reported. Activated phenols react rapidly with ethyl acetoacetate, propenoic acid and propynoic acid under microwave irradiation using cation-exchange resins as catalyst <99SL608>. Similarly, salicylaldehydes are converted into coumarin-3-carboxylic acids when the reaction with malonic acid is catalysed by the montmorillonite KSF <99JOC1033>. In both cases the use of a solid catalyst has environmentally friendly benefits. Methyl 3-(3-coumarinyl)propenoate 44, prepared from dimethyl glutaconate and salicylaldehyde, is a stable electron deficient diene which reacts with enamines to form benzo[c]coumarins. An inverse electron demand Diels-Alder reaction is followed by elimination of a secondary amine and aromatisation (Scheme 26) <99SL477>. 

Benzoe Siam resinoid is obtained by solvent extraction of the resin from Styrax tonkinensis (Pierre) Craib ex Hartwich trees (Styracaceae). The wild growing Styrax tree is widespread in Thailand, Laos, Cambodia, and Vietnam. 

Figure 3. Total ion chromatogram of extractable organics in a typical lot of Ambersorb XE-340 resin (SP-2100,10-m capillary column, temperature program 50(2)-250 at 5 °C/min, 1.0-pL splitless injection). 1, naphthalene 2,1- or 2-methylnaphthalene 3, biphenyl 4, 1,V-biphenyl, 2- or 3-methyl 5, fluorene 6, anthracene-phenanthrene 7tl- or 2-phenylnaphthalene 8, pyrene 9, fluoranthene 10, terphenyl isomer 11, benzo[b]naphthothiophene isomer 12, binaphthalene isomer 13, benzofluoranthene isomer. (Reproduced from...

Benzo[6 ]furan (2), usually called simply benzofuran, was first prepared by Perkin, who obtained it from coumarin as in Scheme 2 and (not understanding its constitution) called it coumarone, an unsuitable name that still survives in the term coumarone resin , for the compound is now valued for copolymerization purposes. Later the compound was isolated by distillation of bituminous coal, which is also a source of several methyl and hydroxy derivatives and of dibenzofuran (the name diphenylene oxide is now discarded) <75AHC(18)337>. 

Thiophenes are known to polymerize on treatment with acidic materials this is probably due to successive protonation and electrophilic substitution. It has been reported (79BCJ1126) that 2-chlorothiophene (80) on treatment with Amberlyst 15 (cation exchange resin) and 100% orthophosphoric acid gives (82) and (84) as major products and (83) as a minor one. The suggested mechanism involves initial protonation to form (81), which subsequently acts as an electrophile (Scheme 13). Related dimerizations have been reported on treatment of benzo[6]thiophene with A1C13 <80JCS(P1)677, 81JCR(S)307>. 

C) Preparation of 9,10-Dihydro-4H-Benzo[4,5]Cyclohepta[l,2-b]Thiophen-(4)-One 200 ml of 85% phosphoric acid and 112 g of phosphorus pentoxide are heated to 135°C. 7.0 g of o-[2-thienyl-(2 )-ethyl]benzoic acid are then introduced while stirring thoroughly over a period of 30 min. Stirring is then continued for another hour at 135°C and the reaction mixture is then stirred into 1 liter of ice water. Extraction is then effected 3 times, using 250 ml ether portions, the ethereal extract is washed with 2 N sodium carbonate solution, dried over sodium sulfate and reduced in volume by evaporation. The residue is boiled up with 55 ml of ethanol, the solution freed of resin by decanting and then stirred at room temperature for 6 hours with animal charcoal. It is then filtered off, reduced in volume in a vacuum and the residue distilled. BP 120° to 124°C/0.005 mm, nD24-5 = 1.6559. 

Nal, phase transfer catalyst Nal, CH3COCH3 Nal, HMPA Nal, benzo-15-crown-5 Nal, ion exchange resin Nal, (Me4N)Cl-silica cat Nal, Mel KI, DMF... 

The benzo-l,5-oxazocine 523 was obtained utilizing the UgiH-component reaction (IMCR). Reaction of 2-fluoro-5-nitrobenzoic acid 518 with 3-phenylpropionaldehyde 519, cyclohexyl isocyanide 521, and the aminopropanol 520 afforded the Ugi-product 522 which was subjected to treatment with TFA followed by proton scavenging with resin, to promote cyclization to give 1,5-oxazocine 523 (60% yield) (Scheme 105) <2001TL4963>. 

The distribution of the emitted PAH between the four traps, the cyclones, the condenser, the Teflon filter and the XAD-2 resin, with sand and limestone beds, is shown in Table 3. In spite that the 16 PAH listed by USEPA were comprised in this study, only Fluorene, Pyrene, Acenaphthene, Benzo(a)Anthracene and Coronene could be quantified. Three other PAH, Benzo(a)Pyrene, Chrysene and Anthracene, were detected but were emitted below quantification limits. The remaining studied PAH were not detected. 

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