Carbon zinc chloride, primary

Carbon-zinc and carbon-zinc chloride primary batteries... 

Within each Part, chapters are included on all available types of primary batteries, secondary batteries and batteries available in primary and secondary versions. The primary batteries include carbon-zinc, carbon-zinc chloride, mercury-zinc and other mercury types, manganese dioxide-magnesium perchlorate, magnesium organic, lithium types (sulphur dioxide, thionyl chloride, vanadium pentoxide, iodine and numerous other lithium types), thermally activated and seawater batteries. Batteries available in primary and secondary Corms include alkaline manganese, silver-zinc, silver-cadmium, zinc-air and cadmium-air. The secondary batteries discussed include lead-acid, the nickel types (cadmium, iron, zinc, hydrogen), zinc-chlorine, sodium-sulphur and other fast ion types. 

Carbon-zinc batteries (primary)and carbon-zinc chloride batteries 54/3... 

D—Leclanche Zinc anode Carbon, silver chloride, and air Primary and secondary Zinc—air batteries, carbon—zinc batteries, and silver chloride-zinc batteries... 

Cost The cost of the battery is determined by the materials used in its fabrication and the manufacturing process. The manufacturer must be able to make a profit on the sale to the customer. The selling price must be in keeping with its perceived value (tradeoff of the ability of the user to pay the price and the performance of the battery). Alkaline primary Zn—MnOz is perceived to be the best value in the United States. However, in Europe and Japan the zinc chloride battery still has a significant market share. In developing countries, the lower cost Leclanche carbon—zinc is preferred. Likewise, lead acid batteries are preferred for automobile SLI over Ni—Cd with superior low-temperature performance but with a 10 times higher cost. 

Dry cells have been well-known for over 100 years and form the technical basis of today s modern dry cell industry. Zinc carbon cells are the most widely used of all the primary batteries worldwide because of their low cost, availability, and acceptability in various situations. The two major separator types ever used or in use are gelled paste and paper coated with cereal or other gelling agents such as methyl-cellulose. The paste type is dispensed into the zinc can, and the preformed bobbin is inserted, pushing the paste up the can walls between the zinc and the bobbin. A typical paste electrolyte uses zinc chloride, ammonium chloride, water, and starch or flour as the gelling agents. The coated-paper type uses a special paper coated with flour, starch, regenerated cellulose. 

The prominent role of alkyl halides in formation of carbon-carbon bonds by nucleophilic substitution was evident in Chapter 1. The most common precursors for alkyl halides are the corresponding alcohols, and a variety of procedures have been developed for this transformation. The choice of an appropriate reagent is usually dictated by the sensitivity of the alcohol and any other functional groups present in the molecule. Unsubstituted primary alcohols can be converted to bromides with hot concentrated hydrobromic acid.4 Alkyl chlorides can be prepared by reaction of primary alcohols with hydrochloric acid-zinc chloride.5 These reactions proceed by an SN2 mechanism, and elimination and rearrangements are not a problem for primary alcohols. Reactions with tertiary alcohols proceed by an SN1 mechanism so these reactions are preparatively useful only when the carbocation intermediate is unlikely to give rise to rearranged product.6 Because of the harsh conditions, these procedures are only applicable to very acid-stable molecules. 

The name Leclanche cell is given to the familiar primary system consisting of a zinc anode, manganese dioxide cathode and an electrolyte of ammonium chloride and zinc chloride dissolved in water. The alternative designation zinc-carbon ceir is broader and includes the so-called zinc chloride system which, due to a different electrolyte composition, is characterized by a different discharge mechanism. The Leclanche cell may be written as... 

Many metal salts are well-known primary skin irritants. These substances include antimony trioxide, arsenic trioxide, chromium and alkaline chromates, cobalt sulfate, nickel sulfate, mercury chloride, and zinc chloride. In addition to the above industrial chemicals, several solvents are known to act as primary skin irritants among workers, such as, carbon tetrachloride (CCI4), chloroform, ethylene dichloride, epichlorohydrin, ethylene chlorohydrin, perchloroethylene, and trichloroethylene, in addition to cool tar solvents such as naphtha, toluene, and xylene. 

Leclanche cells are the least expensive primary batteries. The first zinc-manganese dioxide cell was developed by Georges Leclanche in 1866. He developed the primary battery with an ammonium chloride and zinc chloride electrolyte, and with a natural Mn02 and carbon (usually acetylene black) cathode inserted into a zinc can. His name is still associated with this chemistry today. The battery reactions are given in Equation 10.1. 

Whether an alcohol is primary, secondary, or tertiary is shown by the Lucas test, which is based upon the difference in reactivity of the three classes toward hydrogen halides (Sec. 16.4). Alcohols (of not more than six carbons) are soluble in the Lucas reagent, a mixture of concentrated hydrochloric acid and zinc chloride. (Why are they more soluble in this than in water ) The corresponding alkyl chlorides are insoluble. Formation of a chloride from an alcohol is indicated by the cloudiness that appears when the chloride separates from the solution hence, the time required for cloudiness to appear is a measure of the reactivity of the alcohol. 

In the zinc chloride cell, precipitated basic zinc chloride is the primary anode product because of the low concentration of ammonium chloride in the cell. Water and zinc chloride are consumed in equations 1 and 7 and must be provided in adequate amounts for the cell to discharge efficiently. Usually more carbon is used in zinc chloride cells than in Leclanchn cells in order to increase the electrolyte absorptivity of the cathode and thus allow the use of a larger volume of electrolyte. Also, the use of a thin paper separator, which decreases internal resistance, allows less space for water storage than the thick, pasted separator construction traditionally used in Ledanchit cells. 

Condensing agents are basic catalysts such as alkali carbonates, hydrogen carbonates, hydroxides, or alkoxides, or primary aliphatic amines or calcium hydroxide zinc chloride may also be used with aromatic aldehydes. Ethylene-diamine was introduced by Lerner972 for use in the synthesis of unsaturated nitriles in the aromatic series and he gave a large number of examples in which yields were around 95%. 

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