Hypericin, the photodynamically active plant pigment, has a molecular formula C30H16O8. Kuhn–Roth analysis shows two C—Me groups and benzoylation gives a yellow hexabenzoate. Reductive benzoylation of hypericin, on the other hand, affords a blue octabenzoate. These observations led Brockmann and his colleagues to the conclusion that hypericin is a hexahydroxyquinone. The fact that zinc dust distillation of hypericin yields meso-anthrodianthrene (CLXXV) without loss of carbon atoms, allows only two possible extended quinonoid systems (CLXXVI) and (CLXXVII) for hypericin. The shift of the ultraviolet spectrum in alkaline solution and the reactivity of the hydroxyl groups suggested the presence of a number of OH groups in the peri-positions to the quinone carbonyl functions. Since only two of the six hydroxyl functions are acetylated by keten, the remaining four OH groups were assumed to be in peri-positions.


    Brockmann61 next devised a spectroscopic method for the identification of parent hydrocarbons of polycyclic hydroxyquinones. This employed the technique of reductive acetylation to the corresponding polyacetoxy-hydrocarbon, whose spectrum closely resembles that of the parent hydrocarbon in shape and band spacings with the maxima shifted slightly to longer wavelengths by the presence of the acetoxyl groups which correspond roughly to methyl groups in their power of bathochromic displacement. Thus 1,4,5-trihydroxyanthraquinone on reductive acetylation gives 1,4,5,9,10-penta-acetoxyanthracene, the latter having λmax 350, 370, 385, and 410 mμ in dioxan. For comparison, anthracene in this solvent has bands at 325, 340, 360 and 378 mμ, the shapes of these curves being very similar. For strict comparison it would be necessary to have 1,4,5, 9,10-pentamethylanthracene available. Since it is often difficult to obtain reference samples of such complexity, the working rule of a red shift of the entire spectrum of 5 mμ for each acetoxyl group added to the hydrocarbon gives generally adequate agreement.


    We now return to the reductive acetylation of hypericin. On the basis of partial structures (CLXXVI) and (CLXXVII) we should expect to be able to distinguish between the parent systems generated by zinc treatment, viz. 2,2-dimethylhelianthrene (CLXXVIIIa) and 2,2′-dimethylmesonaphthodianthrene (CLXXVIIIb). The maxima of these hydrocarbons are sufficiently disparate for such a decision to be made, for the former has its longest band at 543 mμ and is red, while the latter absorbs in the visible at 627 mμ and is coloured blue. In the event, reductive acetylation of hypericin gives a blue hexa-acetate whose spectrum is almost identical with that of (CLXXVIIIb) and whose longest wavelength band is at 625 mμ. Now this is at first sight a surprising result, for we should expect a bathochromic shift of 30 mμ of the spectrum of the hydrocarbon by the introduction of six acetoxyl groups. The desmethyl hydrocarbon (CLXXIX) itself, however, has λmax 605 and 660 mμ in the visible region, the 3,3′-dimethyl derivative λmax 609 and 663 and the 10,10′-diacetate 626 and 678 mμ.

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    The RV Inverter Guide for Beginners What's an RV inverter and do you need one? How do you choose the right inverter for your RV and how do you go about installing it? We were able to consult RV expert, Gary Brinck, on this topic to put together this concise guide for you. You may have noticed that the 120v wall outlets in your RV only work when plugged into shore power or when using a generator. That probably includes the microwave and TV as well. That means your RV is not equipped with an inverter. To find out more about RV inverters, keep reading. What’s An RV Inverter? The inverter is an electronic module that gives the capability to power things that normally require 120VAC shore power (when not using a generator). Having an inverter is hugely convenient if you like to camp off the power grid but still want to watch TV or charge up your phone. Mid- and high-end RVs often come with inverters already installed. They serve just a few items or maybe even all the outlets in the RV. The good news is that if your RV doesn’t have an inverter, you can add one! Sounds attractive, right? However, except for the simplest needs, adding an inverter is a major change in how the 120VAC system in your RV works. In most cases, it's not what you would call a “plug ‘n play” upgrade. How Does An RV Inverter Work? An inverter uses the RV’s 12v batteries to supply the power and inverts the battery 12VDC to become 120VAC power for the outlets. In theory, you can power everything with a large enough inverter, even the air conditioning. However, the inverter cannot provide more power than the battery bank that supplies it. The laws of electricity are that increasing the power output from 12v to 120v (a factor of 10x increase) causes a 10x increase in the input amps (current) as well. That means a high wattage appliance like an AC unit or hair dryer that draws a lot of amps will pull a huge amperage from the batteries. For example, a 1500 watt appliance uses 12.5 amps @ 120v, so it will draw a minimum of 125 amps from the batteries when inverting from 12v to 120v. There is also a power loss of around 10% when inverting. A rule of thumb is that the inverter will draw about 10% more battery amps than actually needed by the power conversion. This is called the efficiency of the inverter and 90%-95% is typical. Since a typical RV battery can supply only 50-70 amps for a mere hour, you can see that batteries quickly become the bottleneck if you try to do too much. The cost, weight, and space needed for a large battery bank are prohibitive for most RVers. For practical purposes, you will want to limit what things you expect to power.


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