Sun lamps

Alkyl mercury halides participate in a photo-sdmidated rathcM chain reacdon of the anion of nitroalkanes Isee Eq. 5.38 in which a 375-W sun lamp Is used." Primary, secondary, and ternary alkyl rathcMs generated from alkyl mercury halides react with the anion of ttitroalkanes to form new C-C bonds. 

Avoid sun lamps and tanning beds, which provide an additional source of UV radiation. 

The simplest and of course the most inexpensive external light source is the sun. This source, however, is not always as dependable and reproducible as the photochemist would like. Alternatively, a sun lamp, whose... 

A tandem radical addition/cyclization process has been described for the formation of benzindolizidine systems from l-(2-iodoethyl)indoles and methyl acrylate <00TL10181>. In this process, sun-lamp irradiation of a solution of the l-(2-iodoethyl)ethylindoles 149 in refluxing benzene containing hexamethylditin and methyl acrylate effects intermolecular radical addition to the activated double bond leading to the stabilized radical 150. Intramolecular cyclization to the C-2 position of the indole nucleus then affords the benzindolzidine derivatives 151 after rearomatization of the tricyclic radical. 

Irradiation with a sun lamp or addition of one drop of concentrated hydrochloric acid may be necessary to initiate the bromination. 

The allyloxy and propargyloxy compounds are easily prepared by the opening of mono-substituted epoxides with sodium aryl tellurolates, followed by allylation and propargyla-tion of the obtained -hydroxytellurides, submitted to irradiation with a sun lamp in the presence of hexabutylditin, and suffer group-transfer cyclization under 5-exo-mode to give the 2,4-disubstituted tetrahydrofuran derivatives. ... 

Ciufolini et al. (61) reported a facile assembly of the benzazocenone 307 as a part of the total synthesis of the antitumor alkaloids mitomycin C (309) and FR 900482 (310) based on intramolecular 1,3-dipolar cycloadditions of aryl azides with electron-rich alkenes (Scheme 9.61). Azide 305 was heated in refluxing toluene with a catalytic amount of K2CO3 to give the triazoline 306 in 55% yield. Irradiation of a solution of the triazoline 306 in wet THF with a sun lamp gave an 84% yield of the required benzazocene 308, which was converted to the target molecules 309 and 310. 

A. a,a,ot, a -Tetrabromo-o-xylene. In a 2-1. three-necked flask equipped with an oil-lubricated Trubore stirrer, a dropping funnel, a thermometer extending nearly to the bottom of the flask, and a reflux condenser (Note 1) attached to a gas absorption trap 2 is placed 117 g. (1.1 moles) of dry o-xylene (Note 2). An ultraviolet lamp such as a General Electric R.S. Reflector Type 275-watt sun lamp is placed about 1 cm. from the flask so as to admit the maximum amount of light. The stirrer is started, and the o-xylene is heated to 120° with an electric heating mantle. A total of 700 g. (4.4 moles) of bromine (n.f. grade) is added in portions from the dropping funnel to the reaction flask at such a rate that the bromine color is removed as fast as it is added. 

The submitters employed a 600-watt lamp, and the checkers used a 275-watt General Electric sun lamp. 

Avoid exposure to bright lights (i.e., sun lamps) for one to three hours prior to bedtime, since this can throw off your body s biological clock. 

Treatment of 4-pentenyl iodoacetate (221) with bis(tributyltin) at room temperature under irradiation with a sun lamp generates 7-iodoheptanolactone (222a), which is an atom-transfer cyclization product (eq. 3.87) [234]. 

Boron trifluoride etherate (0.37 ml, 3 mmol) was added to a benzene (33 ml) solution of 4-pentenyl iodoacetate (1.0 mmol) under a nitrogen atmosphere at room temperature. Z Lv(tributyltin) (0.1 mmol) was added and the mixture was irradiated with a 300 W sun lamp at 20 °C. After 6 h, the solvent was removed and the residue was chromatographed on silica gel (hexane /ethyl acetate = 2/1) to produce the iodolactone in 80% yield [234]. 

Some Japanese chemists needed the E,E-diene below for a synthesis of a neurotoxic compound that they had isolated from poison dart frogs. Unfortunately, their synthesis (which used a Wittig reaction—Chapter 14 and later in this chapter) gave only 4 1 E selectivity at one of the double bonds. To produce pure E,E-diene, they equilibrated the ,Z-diene to , by treating with iodine and irradiating with a sun-lamp. 

Light from a sun-lamp was used in a recent example to equilibrate an alkene with iodine. Iodine is brown and absorbs visible light well. In the present example there Is no iodine and UV light is used, which Is absorbed by the alkene itself. See Chapter 7 for orbital diagrams. 

A sun lamp situated close to the funnel may be required to prevent solidification of the Diels-Alder adduct. 

A good fractionating column is required to separate the 1,4-dichlorobutadiene from the dichlorocyclobutene. At 55 mm. the dichlorobutadiene will distill at 58-62° after this material has been removed, the temperature will rise fairly sharply to 70° and at this point the reflux ratio may then be reduced from 10 1 to zero and the dichlorocyclobutene collected quickly. It usually is necessary to apply heat frequently with a sun lamp to prevent solidification of the dichlorobutadiene in the exit tube of the distillation apparatus, especially if the receiving flask is kept cold. 

Donohoue et al. [31] has reported two other kinetic data sets for Cl and Br reactions using a pulsed laser photolysis-pulsed laser induced fluorescence spectroscopy. These data sets are obtained using pseudo-first order conditions with respect to halogens or mercury and experiments were performed at a broad range of temperatures. The authors of these studies indicate an uncertainty estimation of 50% in the rate coefficients due to the determination of absolute concentrations of chlorine and bromine atoms [31]. Sumner et al. [20] reinvestigated both reactions using a 17.3 m environmental chambers equipped with fluorescent lamps and sun lamps to mimic environmental reactions, and evaluated the rate constants... 

---