It is a most important synthetic reagent; with sodium or sodium ethylate it forms sodio-malonic ester, which reacts readily with alkyl halides, forming alkyl malonic esters, which are again capable of forming sodium derivatives, that by further treatment with alkyl halides yield the di-alkyl malonic esters.
The N-derivatives are prepared by the action of alkyl halides and acid chlorides on potassium pyrrol.
The older methods used for the preparation of the amorphous form, namely the decomposition of silicon halides or silicofluorides by the alkali metals, or of silica by magnesium, do not give good results, since' the silicon obtained is always contaminated with various impurities, but a pure variety may be prepared according to E.
The organic derivatives of silicon resemble the corresponding carbon compounds except in so far that the silicon atom is not capable of combining with itself to form a complex chain in the same manner as the carbon atom, the limit at present being a chain of three silicon atoms. Many of the earlier-known silicon alkyl compounds were isolated by Friedel and Crafts and by Ladenburg, the method adopted consisting in the interaction of the zinc alkyl compounds with silicon halides or esters of silicic acids.
Taurke (Ber., 1905, 38, p. 1663) by condensing silicon halides with alkyl chlorides in the presence of sodium: SiC14-1-4R Cl+8Na= SiR 4 +8NaCI; SiHC1 3 +3R.
Soc., 1904, 20, p. 15) has used silicon halides with the Grignard reagent: C2H,MgBr(+SiC14)-C2HiSiC13(-1-MgBrPh)--> Ph C 2 H 1.
The atomic weight of silicon has been determined usually by analysis of the halide compounds or by conversion of the halides into silica.
The mixed tertiary amines are produced by the action of alkyl halides on the primary amines.
Ammonia gas has the power of combining with many substances, particularly with metallic halides; thus with calcium chloride it forms the compound CaCl 2.8NH 3, and consequently calcium chloride cannot be used for drying the gas.
They may also be prepared by eliminating the halogen hydride from the alkyl halides by heating with alcoholic potash, or with litharge at 220° C. (A.
Chablay, Comptes rendus, 1906, 1 43, p. 123) 2CH 2 :CH CH 2 OH+2NH 3 Na = CH,:CH CH3+CH2:CH CH20Na +NaOH+2NH31 from the lower members of the series by heating them with alkyl halides in the presence of lead oxide or lime: C5H,9-I-2CH31 =2H1+ C 7 H, 4 i and by the action of the zinc alkyls upon the halogen substituted olefines.
As unsaturated compounds they can combine with two monovalent atoms. Hydrogen is absorbed readily at ordinary temperature in the presence of platinum black, and paraffins are formed; the halogens (chlorine and bromine) combine directly with them, giving dihalogen substituted compounds; the halogen halides to form monohalogen derivatives (hydriodic acid reacts most readily, hydrochloric acid, least); and it is to be noted that the haloid acids attach themselves in such a manner that the halogen atom unites itself to the carbon atom which is in combination with the fewest hydrogen atoms (W.
Grignard (Comptes rendus, 1900 et seq.) observed that magnesium and alkyl or aryl halides combined together in presence of anhydrous ether at ordinary R temperatures (with the appearance of brisk boiling) to form compounds of the type RMgX(R = an alkyl or aryl group and X = halogen).
With unsaturated alkyl halides the products are only slightly soluble in ether, and two molecules of the alkyl compound are brought into the reaction.
They may also be prepared by heating the alkyl halides with silver oxide.
Chem., 1862, 1, p. 519) and Godeffroy (Ann., 1876, 181, p. 185), the methods being based on the conversion of rubidium halides into the corresponding silver salt, and the values obtained vary from 85.40 to 85.50.
It is a tertiary base, and combines readily with the alkyl halides to form pyridinium salts.