NOVELTY - Preparing an alkyl compound or a mixture of alkyl compounds, comprises: (a) preparing a ketene compound (I); (b) reacting the ketene in a self-addition reaction to form a diketene compound (II); and (c) hydrogenating the diketene in the presence of a metal catalyst to form the alkyl compound or the mixtures of alkyl compounds.    USE - The method is useful for preparing alkyl compound or mixture of alkyl compounds, which is useful as fuel, and a raw material for chemical processing (claimed).    DETAILED DESCRIPTION - Preparing an alkyl compound or a mixture of alkyl compounds, comprises: (a) preparing a ketene compound of formula ((R1)(R2)=O=O) (I); (b) reacting the ketene in a self-addition reaction to form a diketene compound of formula (II); and (c) hydrogenating the diketene in the presence of a metal catalyst to form the alkyl compound or the mixtures of alkyl compounds.R1, R2 = H or 1-6C-alkyl.    INDEPENDENT CLAIMS are included for:    (1) a method-II for the preparation of a 4-6C alcohol comprising preparing a beta-lactone compound of formula (IIIa), and hydrogenating the lactone to form the 4-6C alcohol;    (2) a method-III for preparing 3-pentanol comprising carbonylating ethanol to form propanoic acid, ketonizing propanoic acid to form 3-pentanone, and hydrogenating 3-pentanone in the presence of a catalyst to form 3-pentanol, and optionally further dehydrating the 3-pentanol to form 2-pentene, and optionally dimerizing the 2-pentene with a zeolite catalyst to form a 10C hydrocarbon;    (3) a method-IV for preparing propanol and/or butanol, comprising carbonylation of methanol or ethanol to form acetic acid or propanoic acid, respectively, and reduction of acetic acid or propanoic acid to form ethanol or propanol, respectively, carbonylation of ethanol or propanol to from propanoic acid or butanoic acid, respectively, or carbonylation of a mixture of ethanol and propanol to form a mixture of propionic acid and butyric acid, and reduction of butanoic acid to form butanol, and optionally hydrogenating a mixture of propionic acid and butyric acid to form a mixture of propanol and butanol; and    (4) a fuel composition comprising the alkane compounds prepared by the method.    R3 = H or 1-2C alkyl; either    R4 = H; and    R5 = H or 1-2C alkyl; or    R4R5 = ethyledene or methyledene.